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docs: provide CN translation for api-guides/performance/ram-usage.rst
This commit is contained in:
caixinying-git
@@ -19,6 +19,6 @@ Guides
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.. toctree::
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:maxdepth: 2
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Execution Speed <speed>
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Binary Size <size>
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RAM Usage <ram-usage>
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speed
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size
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ram-usage
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@@ -1,117 +1,133 @@
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Minimizing RAM Usage
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====================
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:link_to_translation:`zh_CN:[中文]`
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{IDF_TARGET_STATIC_MEANS_HEAP:default="Wi-Fi library, Bluetooth controller", esp32s2="Wi-Fi library", esp32c6="Wi-Fi library, Bluetooth controller, IEEE 802.15.4 library", esp32h2="Bluetooth controller, IEEE 802.15.4 library"}
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In some cases, a firmware application's available RAM may run low or run out entirely. In these cases, it's necessary to tune the memory usage of the firmware application.
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In some cases, a firmware application's available RAM may run low or run out entirely. In these cases, it is necessary to tune the memory usage of the firmware application.
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In general, firmware should aim to leave some "headroom" of free internal RAM in order to deal with extraordinary situations or changes in RAM usage in future updates.
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In general, firmware should aim to leave some headroom of free internal RAM to deal with extraordinary situations or changes in RAM usage in future updates.
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Background
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----------
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Before optimizing ESP-IDF RAM usage, it's necessary to understand the basics of {IDF_TARGET_NAME} memory types, the difference between static and dynamic memory usage in C, and the way ESP-IDF uses stack and heap. This information can all be found in :doc:`/api-reference/system/mem_alloc`.
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Before optimizing ESP-IDF RAM usage, it is necessary to understand the basics of {IDF_TARGET_NAME} memory types, the difference between static and dynamic memory usage in C, and the way ESP-IDF uses stack and heap. This information can all be found in :doc:`/api-reference/system/mem_alloc`.
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Measuring Static Memory Usage
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-----------------------------
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The :ref:`idf.py` tool can be used to generate reports about the static memory usage of an application. Refer to :ref:`the Binary Size chapter for more information <idf.py-size>`.
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The :ref:`idf.py` tool can be used to generate reports about the static memory usage of an application, see :ref:`idf.py-size`.
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Measuring Dynamic Memory Usage
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------------------------------
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ESP-IDF contains a range of heap APIs for measuring free heap at runtime. See :doc:`/api-reference/system/heap_debug`.
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ESP-IDF contains a range of heap APIs for measuring free heap at runtime, see :doc:`/api-reference/system/heap_debug`.
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.. note::
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In embedded systems, heap fragmentation can be a significant issue alongside total RAM usage. The heap measurement APIs provide ways to measure the "largest free block". Monitoring this value along with the total number of free bytes can give a quick indication of whether heap fragmentation is becoming an issue.
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In embedded systems, heap fragmentation can be a significant issue alongside total RAM usage. The heap measurement APIs provide ways to measure the largest free block. Monitoring this value along with the total number of free bytes can give a quick indication of whether heap fragmentation is becoming an issue.
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Reducing Static Memory Usage
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----------------------------
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- Reducing the static memory usage of the application increases the amount of RAM available for heap at runtime, and vice versa.
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- Generally speaking, minimizing static memory usage requires monitoring the .data and .bss sizes. For tools to do this, see :ref:`idf.py-size`.
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- Internal ESP-IDF functions do not make heavy use of static RAM allocation in C. In many instances (including: {IDF_TARGET_STATIC_MEANS_HEAP}) "static" buffers are still allocated from heap, but the allocation is done once when the feature is initialized and will be freed if the feature is deinitialized. This is done in order to maximize the amount of free memory at different points in the application life-cycle.
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- Generally speaking, minimizing static memory usage requires monitoring the ``.data`` and ``.bss`` sizes. For tools to do this, see :ref:`idf.py-size`.
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- Internal ESP-IDF functions do not make heavy use of static RAM in C. In many instances (such as {IDF_TARGET_STATIC_MEANS_HEAP}), static buffers are still allocated from the heap. However, the allocation is performed only once during feature initialization and will be freed if the feature is deinitialized. This approach is adopted to optimize the availability of free memory at various stages of the application's life cycle.
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To minimize static memory use:
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.. list::
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- Declare structures, buffers, or other variables ``const`` whenever possible. Constant data can be stored in flash not RAM. This may require changing functions in the firmware to take ``const *`` arguments instead of mutable pointer arguments. These changes can also reduce the stack usage of some functions.
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:SOC_BT_SUPPORTED: - If using Bluedroid, setting the option :ref:`CONFIG_BT_BLE_DYNAMIC_ENV_MEMORY` will cause Bluedroid to allocate memory on initialization and free it on deinitialization. This doesn't necessarily reduce the peak memory usage, but changes it from static memory usage to runtime memory usage.
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- If :doc:`Coredump </api-guides/core_dump>` component is enabled, `ESP_COREDUMP_LOG` macros will use ~5KB internal memory to place strings into DRAM. By disabling :ref:`CONFIG_ESP_COREDUMP_LOGS` option, these logs are disabled and the memory is reclaimed.
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- Constant data can be stored in flash memory instead of RAM, thus it is recommended to declare structures, buffers, or other variables as ``const``. This approach may require modifying firmware functions to accept ``const *`` arguments instead of mutable pointer arguments. These changes can also help reduce the stack usage of certain functions.
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:SOC_BT_SUPPORTED: - If using Bluedroid, setting the option :ref:`CONFIG_BT_BLE_DYNAMIC_ENV_MEMORY` will cause Bluedroid to allocate memory on initialization and free it on deinitialization. This does not necessarily reduce the peak memory usage, but changes it from static memory usage to runtime memory usage.
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.. _optimize-stack-sizes:
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Reducing Stack Sizes
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--------------------
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In FreeRTOS, task stacks are usually allocated from the heap. The stack size for each task is fixed (passed as an argument to :cpp:func:`xTaskCreate`). Each task can use up to its allocated stack size, but using more than this will cause an otherwise valid program to crash with a stack overflow or heap corruption.
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In FreeRTOS, task stacks are usually allocated from the heap. The stack size for each task is fixed and passed as an argument to :cpp:func:`xTaskCreate`. Each task can use up to its allocated stack size, but using more than this will cause an otherwise valid program to crash, with a stack overflow or heap corruption.
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Therefore, determining the optimum sizes of each task stack can substantially reduce RAM usage.
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Therefore, determining the optimum sizes of each task stack, minimizing the required size of each task stack, and minimizing the number of task stacks as whole, can all substantially reduce RAM usage.
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To determine optimum task stack sizes:
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To determine the optimum size for a particular task stack, users can consider the following methods:
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- Combine tasks. The best task stack size is 0 bytes, achieved by combining a task with another existing task. Anywhere that the firmware can be structured to perform multiple functions sequentially in a single task will increase free memory. In some cases, using a "worker task" pattern where jobs are serialized into a FreeRTOS queue (or similar) and then processed by generic worker tasks may help.
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- Consolidate task functions. String formatting functions (like ``printf``) are particularly heavy users of stack, so any task which doesn't ever call these can usually have its stack size reduced.
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- Enabling :ref:`newlib-nano-formatting` will reduce the stack usage of any task that calls ``printf()`` or other C string formatting functions.
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- Avoid allocating large variables on the stack. In C, any large struct or array allocated as an "automatic" variable (i.e. default scope of a C declaration) will use space on the stack. Minimize the sizes of these, allocate them statically and/or see if you can save memory by allocating them from the heap only when they are needed.
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- Avoid deep recursive function calls. Individual recursive function calls don't always add a lot of stack usage each time they are called, but if each function includes large stack-based variables then the overhead can get quite high.
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- At runtime, call the function :cpp:func:`uxTaskGetStackHighWaterMark` with the handle of any task where you think there is unused stack memory. This function returns the minimum lifetime free stack memory in bytes. The easiest time to call this is from the task itself: call ``uxTaskGetStackHighWaterMark(NULL)`` to get the current task's high water mark after the time that the task has achieved its peak stack usage (i.e. if there is a main loop, execute the main loop a number of times with all possible states and then call :cpp:func:`uxTaskGetStackHighWaterMark`). Often, it's possible to subtract almost the entire value returned here from the total stack size of a task, but allow some safety margin to account for unexpected small increases in stack usage at runtime.
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- Call :cpp:func:`uxTaskGetSystemState` at runtime to get a summary of all tasks in the system. This includes their individual stack "high watermark" values.
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- When debugger watchpoints are not being used, set the :ref:`CONFIG_FREERTOS_WATCHPOINT_END_OF_STACK` option to trigger an immediate panic if a task writes the word at the end of its assigned stack. This is slightly more reliable than the default :ref:`CONFIG_FREERTOS_CHECK_STACKOVERFLOW` option of "Check using canary bytes", because the panic happens immediately, not on the next RTOS context switch. Neither option is perfect, it's possible in some cases for stack pointer to skip the watchpoint or canary bytes and corrupt another region of RAM, instead.
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- At runtime, call the function :cpp:func:`uxTaskGetStackHighWaterMark` with the handle of any task where you think there is unused stack memory. This function returns the minimum lifetime free stack memory in bytes.
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Internal Stack Sizes
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^^^^^^^^^^^^^^^^^^^^
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- The easiest time to call :cpp:func:`uxTaskGetStackHighWaterMark` is from the task itself: call ``uxTaskGetStackHighWaterMark(NULL)`` to get the current task's high water mark after the time that the task has achieved its peak stack usage, i.e., if there is a main loop, execute the main loop a number of times with all possible states, and then call :cpp:func:`uxTaskGetStackHighWaterMark`.
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- Often, it is possible to subtract almost the entire value returned here from the total stack size of a task, but allow some safety margin to account for unexpected small increases in stack usage at runtime.
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- Call :cpp:func:`uxTaskGetSystemState` at runtime to get a summary of all tasks in the system. This includes their individual stack high watermark values.
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- When debugger watchpoints are not being used, users can set the :ref:`CONFIG_FREERTOS_WATCHPOINT_END_OF_STACK` option. This will cause one of the watchpoints to watch the last word of the task's stack. If that word is overwritten (such as in a stack overflow), a panic is triggered immediately. This is slightly more reliable than the default :ref:`CONFIG_FREERTOS_CHECK_STACKOVERFLOW` option of ``Check using canary bytes``, because the panic happens immediately, rather than on the next RTOS context switch. Neither option is perfect. In some cases, it is possible that the stack pointer skips the watchpoint or canary bytes and corrupts another region of RAM instead.
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To reduce the required size of a particular task stack, users can consider the following methods:
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- Avoid stack heavy functions. String formatting functions (like ``printf()``) are particularly heavy users of the stack, so any task which does not ever call these can usually have its stack size reduced.
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- Enabling :ref:`newlib-nano-formatting` reduces the stack usage of any task that calls ``printf()`` or other C string formatting functions.
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- Avoid allocating large variables on the stack. In C, any large structures or arrays allocated as an automatic variable (i.e., default scope of a C declaration) uses space on the stack. To minimize the sizes of these, allocate them statically and/or see if you can save memory by dynamically allocating them from the heap only when they are needed.
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- Avoid deep recursive function calls. Individual recursive function calls do not always add a lot of stack usage each time they are called, but if each function includes large stack-based variables then the overhead can get quite high.
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To reduce the total number of tasks, users can consider the following method:
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- Combine tasks. If a particular task is never created, the task's stack is never allocated, thus reducing RAM usage significantly. Unnecessary tasks can typically be removed if those tasks can be combined with another task. In an application, tasks can typically be combined or removed if:
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- The work done by the tasks can be structured into multiple functions that are called sequentially.
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- The work done by the tasks can be structured into smaller jobs that are serialized (via a FreeRTOS queue or similar) for execution by a worker task.
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Internal Task Stack Sizes
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^^^^^^^^^^^^^^^^^^^^^^^^^
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ESP-IDF allocates a number of internal tasks for housekeeping purposes or operating system functions. Some are created during the startup process, and some are created at runtime when particular features are initialized.
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The default stack sizes for these tasks are usually set conservatively high, to allow all common usage patterns. Many of the stack sizes are configurable, and it may be possible to reduce them to match the real runtime stack usage of the task.
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The default stack sizes for these tasks are usually set conservatively high to allow all common usage patterns. Many of the stack sizes are configurable, and it may be possible to reduce them to match the real runtime stack usage of the task.
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.. important::
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If internal task stack sizes are set too small, ESP-IDF will crash unpredictably. Even if the root cause is task stack overflow, this is not always clear when debugging. It is recommended that internal stack sizes are only reduced carefully (if at all), with close attention to "high water mark" free space under load. If reporting an issue that occurs when internal task stack sizes have been reduced, please always include this information and the specific configuration that is being used.
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If internal task stack sizes are set too small, ESP-IDF will crash unpredictably. Even if the root cause is task stack overflow, this is not always clear when debugging. It is recommended that internal stack sizes are only reduced carefully (if at all), with close attention to high water mark free space under load. If reporting an issue that occurs when internal task stack sizes have been reduced, please always include the following information and the specific configuration that is being used.
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.. list::
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- :ref:`Main task that executes app_main function <app-main-task>` has stack size :ref:`CONFIG_ESP_MAIN_TASK_STACK_SIZE`.
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- :ref:`app-main-task` has stack size :ref:`CONFIG_ESP_MAIN_TASK_STACK_SIZE`.
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- :doc:`/api-reference/system/esp_timer` system task which executes callbacks has stack size :ref:`CONFIG_ESP_TIMER_TASK_STACK_SIZE`.
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- FreeRTOS Timer Task to handle FreeRTOS timer callbacks has stack size :ref:`CONFIG_FREERTOS_TIMER_TASK_STACK_DEPTH`.
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- :doc:`/api-reference/system/esp_event` system task to execute callbacks for the default system event loop has stack size :ref:`CONFIG_ESP_SYSTEM_EVENT_TASK_STACK_SIZE`.
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- :doc:`/api-guides/lwip` TCP/IP task has stack size :ref:`CONFIG_LWIP_TCPIP_TASK_STACK_SIZE`
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:SOC_BT_SUPPORTED: - :doc:`Bluedroid Bluetooth Host </api-reference/bluetooth/index>` have task stack sizes :ref:`CONFIG_BT_BTC_TASK_STACK_SIZE`, :ref:`CONFIG_BT_BTU_TASK_STACK_SIZE`.
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:SOC_BT_SUPPORTED: - :doc:`NimBLE Bluetooth Host </api-reference/bluetooth/nimble/index>` has task stack size :ref:`CONFIG_BT_NIMBLE_HOST_TASK_STACK_SIZE`
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- :doc:`/api-guides/lwip` TCP/IP task has stack size :ref:`CONFIG_LWIP_TCPIP_TASK_STACK_SIZE`.
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:SOC_BT_SUPPORTED: - :doc:`/api-reference/bluetooth/index` have task stack sizes :ref:`CONFIG_BT_BTC_TASK_STACK_SIZE`, :ref:`CONFIG_BT_BTU_TASK_STACK_SIZE`.
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:SOC_BT_SUPPORTED: - :doc:`/api-reference/bluetooth/nimble/index` has task stack size :ref:`CONFIG_BT_NIMBLE_HOST_TASK_STACK_SIZE`.
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- The Ethernet driver creates a task for the MAC to receive Ethernet frames. If using the default config ``ETH_MAC_DEFAULT_CONFIG`` then the task stack size is 4 KB. This setting can be changed by passing a custom :cpp:class:`eth_mac_config_t` struct when initializing the Ethernet MAC.
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- FreeRTOS idle task stack size is configured by :ref:`CONFIG_FREERTOS_IDLE_TASK_STACKSIZE`.
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- If using the :doc:`MQTT </api-reference/protocols/mqtt>` component, it creates a task with stack size configured by :ref:`CONFIG_MQTT_TASK_STACK_SIZE`. MQTT stack size can also be configured using ``task_stack`` field of :cpp:class:`esp_mqtt_client_config_t`.
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- To see how to optimize RAM usage when using ``mDNS``, please check `Performance Optimization <https://docs.espressif.com/projects/esp-protocols/mdns/docs/latest/en/index.html#minimizing-ram-usage>`__.
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- If using the :doc:`/api-reference/protocols/mqtt` component, it creates a task with stack size configured by :ref:`CONFIG_MQTT_TASK_STACK_SIZE`. MQTT stack size can also be configured using ``task_stack`` field of :cpp:class:`esp_mqtt_client_config_t`.
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- To see how to optimize RAM usage when using ``mDNS``, please check `Minimizing RAM Usage <https://docs.espressif.com/projects/esp-protocols/mdns/docs/latest/en/index.html#minimizing-ram-usage>`__.
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.. note::
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Aside from built-in system features such as esp-timer, if an ESP-IDF feature is not initialized by the firmware then no associated task is created. In those cases, the stack usage is zero and the stack size configuration for the task is not relevant.
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Aside from built-in system features such as ESP-timer, if an ESP-IDF feature is not initialized by the firmware, then no associated task is created. In those cases, the stack usage is zero, and the stack-size configuration for the task is not relevant.
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Reducing Heap Usage
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-------------------
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For functions that assist in analyzing heap usage at runtime, see :doc:`/api-reference/system/heap_debug`.
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Normally, optimizing heap usage consists of analyzing the usage and removing calls to ``malloc()`` that aren't being used, reducing the corresponding sizes, or freeing previously allocated buffers earlier.
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Normally, optimizing heap usage consists of analyzing the usage and removing calls to ``malloc()`` that are not being used, reducing the corresponding sizes, or freeing previously allocated buffers earlier.
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There are some ESP-IDF configuration options that can reduce heap usage at runtime:
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.. list::
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- lwIP documentation has a section to configure :ref:`lwip-ram-usage`.
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:SOC_WIFI_SUPPORTED: - :ref:`wifi-buffer-usage` describes options to either reduce numbers of "static" buffers or reduce the maximum number of "dynamic" buffers in use, in order to minimize memory usage at possible cost of performance. Note that "static" Wi-Fi buffers are still allocated from heap when Wi-Fi is initialized and will be freed if Wi-Fi is deinitialized.
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:SOC_WIFI_SUPPORTED: - :ref:`wifi-buffer-usage` describes options to either reduce the number of static buffers or reduce the maximum number of dynamic buffers in use, so as to minimize memory usage at a possible cost of performance. Note that static Wi-Fi buffers are still allocated from the heap when Wi-Fi is initialized, and will be freed if Wi-Fi is deinitialized.
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:esp32: - The Ethernet driver allocates DMA buffers for the internal Ethernet MAC when it is initialized - configuration options are :ref:`CONFIG_ETH_DMA_BUFFER_SIZE`, :ref:`CONFIG_ETH_DMA_RX_BUFFER_NUM`, :ref:`CONFIG_ETH_DMA_TX_BUFFER_NUM`.
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- Several Mbed TLS configuration options can be used to reduce heap memory usage. See the :ref:`Mbed TLS <reducing_ram_usage_mbedtls>` docs for details.
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:esp32: - In single core mode only, it's possible to use IRAM as byte accessible memory (added to the regular heap) by enabling :ref:`CONFIG_ESP32_IRAM_AS_8BIT_ACCESSIBLE_MEMORY`. Note that this option carries a performance penalty and the risk of security issues caused by executable data. If this option is enabled then it's possible to set other options to prefer certain buffers be allocated from this memory: :ref:`mbedTLS <CONFIG_MBEDTLS_MEM_ALLOC_MODE>`, :ref:`NimBLE <CONFIG_BT_NIMBLE_MEM_ALLOC_MODE>`.
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:esp32: - Reduce :ref:`CONFIG_BTDM_CTRL_BLE_MAX_CONN` if using BLE.
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- Several Mbed TLS configuration options can be used to reduce heap memory usage. See the :ref:`reducing_ram_usage_mbedtls` docs for details.
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:esp32: - In single-core mode only, it is possible to use IRAM as byte-accessible memory added to the regular heap by enabling :ref:`CONFIG_ESP32_IRAM_AS_8BIT_ACCESSIBLE_MEMORY`. Note that this option carries a performance penalty, and the risk of security issues caused by executable data. If this option is enabled, then it is possible to set other options to prefer certain buffers allocated from this memory: :ref:`CONFIG_MBEDTLS_MEM_ALLOC_MODE`, :ref:`NimBLE <CONFIG_BT_NIMBLE_MEM_ALLOC_MODE>`.
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:esp32: - Reduce :ref:`CONFIG_BTDM_CTRL_BLE_MAX_CONN` if using Bluetooth LE.
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:esp32: - Reduce :ref:`CONFIG_BTDM_CTRL_BR_EDR_MAX_ACL_CONN` if using Bluetooth Classic.
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.. note::
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There are other configuration options that will increase heap usage at runtime if changed from the defaults. These are not listed here, but the help text for the configuration item will mention if there is some memory impact.
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There are other configuration options that increases heap usage at runtime if changed from the defaults. These options are not listed above, but the help text for the configuration item will mention if there is some memory impact.
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.. _optimize-iram-usage:
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@@ -120,9 +136,9 @@ Optimizing IRAM Usage
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.. only:: not esp32
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The available DRAM at runtime (for heap usage) is also reduced by the static IRAM usage. Therefore, one way to increase available DRAM is to reduce IRAM usage.
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The available DRAM at runtime for heap usage is also reduced by the static IRAM usage. Therefore, one way to increase available DRAM is to reduce IRAM usage.
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If the app allocates more static IRAM than is available then the app will fail to build and linker errors such as ``section `.iram0.text' will not fit in region `iram0_0_seg'``, ``IRAM0 segment data does not fit`` and ``region `iram0_0_seg' overflowed by 84 bytes`` will be seen. If this happens, it is necessary to find ways to reduce static IRAM usage in order to link the application.
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If the app allocates more static IRAM than available, then the app will fail to build, and linker errors such as ``section '.iram0.text' will not fit in region 'iram0_0_seg'``, ``IRAM0 segment data does not fit``, and ``region 'iram0_0_seg' overflowed by 84-bytes`` will be seen. If this happens, it is necessary to find ways to reduce static IRAM usage in order to link the application.
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To analyze the IRAM usage in the firmware binary, use :ref:`idf.py-size`. If the firmware failed to link, steps to analyze are shown at :ref:`idf-size-linker-failed`.
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@@ -130,31 +146,31 @@ The following options will reduce IRAM usage of some ESP-IDF features:
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.. list::
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- Enable :ref:`CONFIG_FREERTOS_PLACE_FUNCTIONS_INTO_FLASH`. Provided these functions are not (incorrectly) used from ISRs, this option is safe to enable in all configurations.
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- Enable :ref:`CONFIG_FREERTOS_PLACE_SNAPSHOT_FUNS_INTO_FLASH`. Enabling this option will place snapshot-related functions, such as ``vTaskGetSnapshot`` or ``uxTaskGetSnapshotAll``, in flash.
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- Enable :ref:`CONFIG_RINGBUF_PLACE_FUNCTIONS_INTO_FLASH`. Provided these functions are not (incorrectly) used from ISRs, this option is safe to enable in all configurations.
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- Enable :ref:`CONFIG_RINGBUF_PLACE_ISR_FUNCTIONS_INTO_FLASH`. This option is not safe to use if the ISR ringbuf functions are used from an IRAM interrupt context, e.g. if :ref:`CONFIG_UART_ISR_IN_IRAM` is enabled. For the IDF drivers where this is the case you will get an error at run-time when installing the driver in question.
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:SOC_WIFI_SUPPORTED: - Disable Wi-Fi options :ref:`CONFIG_ESP_WIFI_IRAM_OPT` and/or :ref:`CONFIG_ESP_WIFI_RX_IRAM_OPT`. Disabling these options will free available IRAM at the cost of Wi-Fi performance.
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:CONFIG_ESP_ROM_HAS_SPI_FLASH: - :ref:`CONFIG_SPI_FLASH_ROM_IMPL` enabling this option will free some IRAM but will mean that esp_flash bugfixes and new flash chip support is not available, see :doc:`/api-reference/peripherals/spi_flash/spi_flash_idf_vs_rom` for details.
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:esp32: - :ref:`CONFIG_SPI_FLASH_ROM_DRIVER_PATCH` disabling this option will free some IRAM but is only available in some flash configurations (see the configuration item help text).
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:esp32: - If the application uses PSRAM and is based on ESP32 rev. 3 (ECO3), setting :ref:`CONFIG_ESP32_REV_MIN` to ``3`` will disable PSRAM bug workarounds, saving ~10kB or more of IRAM.
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- Disabling :ref:`CONFIG_ESP_EVENT_POST_FROM_IRAM_ISR` prevents posting ``esp_event`` events from :ref:`iram-safe-interrupt-handlers` but will save some IRAM.
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- Disabling :ref:`CONFIG_SPI_MASTER_ISR_IN_IRAM` prevents spi_master interrupts from being serviced while writing to flash, and may otherwise reduce spi_master performance, but will save some IRAM.
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- Disabling :ref:`CONFIG_SPI_SLAVE_ISR_IN_IRAM` prevents spi_slave interrupts from being serviced while writing to flash, will save some IRAM.
|
||||
- Setting :ref:`CONFIG_HAL_DEFAULT_ASSERTION_LEVEL` to disable assertion for HAL component will save some IRAM especially for HAL code who calls `HAL_ASSERT` a lot and resides in IRAM.
|
||||
- Refer to sdkconfig menu ``Auto-detect flash chips`` and you can disable flash drivers which you don't need to save some IRAM.
|
||||
- Enable :ref:`CONFIG_HEAP_PLACE_FUNCTION_INTO_FLASH`. Provided that :ref:`CONFIG_SPI_MASTER_ISR_IN_IRAM` is not enabled and the heap functions are not (incorrectly) used from ISRs, this option is safe to enable in all configuration.
|
||||
- Enable :ref:`CONFIG_FREERTOS_PLACE_FUNCTIONS_INTO_FLASH`. Provided these functions are not incorrectly used from ISRs, this option is safe to enable in all configurations.
|
||||
- Enable :ref:`CONFIG_FREERTOS_PLACE_SNAPSHOT_FUNS_INTO_FLASH`. Enabling this option places snapshot-related functions, such as ``vTaskGetSnapshot`` or ``uxTaskGetSnapshotAll``, in flash.
|
||||
- Enable :ref:`CONFIG_RINGBUF_PLACE_FUNCTIONS_INTO_FLASH`. Provided these functions are not incorrectly used from ISRs, this option is safe to enable in all configurations.
|
||||
- Enable :ref:`CONFIG_RINGBUF_PLACE_ISR_FUNCTIONS_INTO_FLASH`. This option is not safe to use if the ISR ringbuf functions are used from an IRAM interrupt context, e.g., if :ref:`CONFIG_UART_ISR_IN_IRAM` is enabled. For the ESP-IDF drivers where this is the case, you can get an error at run-time when installing the driver in question.
|
||||
:SOC_WIFI_SUPPORTED: - Disabling Wi-Fi options :ref:`CONFIG_ESP_WIFI_IRAM_OPT` and/or :ref:`CONFIG_ESP_WIFI_RX_IRAM_OPT` options frees available IRAM at the cost of Wi-Fi performance.
|
||||
:CONFIG_ESP_ROM_HAS_SPI_FLASH: - Enabling :ref:`CONFIG_SPI_FLASH_ROM_IMPL` frees some IRAM but means that esp_flash bugfixes and new flash chip support are not available, see :doc:`/api-reference/peripherals/spi_flash/spi_flash_idf_vs_rom` for details.
|
||||
:esp32: - Disabling :ref:`CONFIG_SPI_FLASH_ROM_DRIVER_PATCH` frees some IRAM but is only available in some flash configurations, see the configuration item help text.
|
||||
:esp32: - If the application uses PSRAM and is based on ESP32 rev. 3 (ECO3), setting :ref:`CONFIG_ESP32_REV_MIN` to ``3`` disables PSRAM bug workarounds, saving 10 KB or more of IRAM.
|
||||
- Disabling :ref:`CONFIG_ESP_EVENT_POST_FROM_IRAM_ISR` prevents posting ``esp_event`` events from :ref:`iram-safe-interrupt-handlers` but saves some IRAM.
|
||||
- Disabling :ref:`CONFIG_SPI_MASTER_ISR_IN_IRAM` prevents spi_master interrupts from being serviced while writing to flash, and may otherwise reduce spi_master performance, but saves some IRAM.
|
||||
- Disabling :ref:`CONFIG_SPI_SLAVE_ISR_IN_IRAM` prevents spi_slave interrupts from being serviced while writing to flash, which saves some IRAM.
|
||||
- Setting :ref:`CONFIG_HAL_DEFAULT_ASSERTION_LEVEL` to disable assertion for HAL component saves some IRAM, especially for HAL code who calls ``HAL_ASSERT`` a lot and resides in IRAM.
|
||||
- Refer to the sdkconfig menu ``Auto-detect Flash chips``, and you can disable flash drivers which you do not need to save some IRAM.
|
||||
- Enable :ref:`CONFIG_HEAP_PLACE_FUNCTION_INTO_FLASH`. Provided that :ref:`CONFIG_SPI_MASTER_ISR_IN_IRAM` is not enabled and the heap functions are not incorrectly used from ISRs, this option is safe to enable in all configurations.
|
||||
|
||||
.. only:: esp32
|
||||
|
||||
Using SRAM1 for IRAM
|
||||
^^^^^^^^^^^^^^^^^^^^
|
||||
|
||||
The SRAM1 memory area is normally used for DRAM, but it is possible to use parts of it for IRAM with :ref:`CONFIG_ESP_SYSTEM_ESP32_SRAM1_REGION_AS_IRAM`. This memory would previously be reserved for DRAM data usage (e.g. bss) by the software bootloader and later added to the heap. After this option was introduced, the bootloader DRAM size was reduced to a value closer to what it normally actually needs.
|
||||
The SRAM1 memory area is normally used for DRAM, but it is possible to use parts of it for IRAM with :ref:`CONFIG_ESP_SYSTEM_ESP32_SRAM1_REGION_AS_IRAM`. This memory would previously be reserved for DRAM data usage (e.g., ``.bss``) by the software bootloader and later added to the heap. After this option was introduced, the bootloader DRAM size was reduced to a value closer to what it normally actually needs.
|
||||
|
||||
This option depends on IDF being able to recognize that the new SRAM1 area is also a valid load address for an image segment. If the software bootloader was compiled before this option existed, then the bootloader will not be able to load an app which has code placed in this new extended IRAM area. This would typically happen if you are doing an OTA update, where only the app would be updated.
|
||||
To use this option, ESP-IDF should be able to recognize that the new SRAM1 area is also a valid load address for an image segment. If the software bootloader was compiled before this option existed, then the bootloader will not be able to load the app that has code placed in this new extended IRAM area. This would typically happen if you are doing an OTA update, where only the app would be updated.
|
||||
|
||||
If the IRAM section were to be placed in an invalid area then this would be detected during the bootup process and result in a failed boot:
|
||||
If the IRAM section were to be placed in an invalid area, then this would be detected during the bootup process, and result in a failed boot:
|
||||
|
||||
.. code-block:: text
|
||||
|
||||
@@ -162,26 +178,27 @@ The following options will reduce IRAM usage of some ESP-IDF features:
|
||||
|
||||
.. warning::
|
||||
|
||||
Apps compiled with :ref:`CONFIG_ESP_SYSTEM_ESP32_SRAM1_REGION_AS_IRAM`, may fail to boot if used together with a software bootloader compiled before this config option was introduced. If you are using an older bootloader and updating over OTA, please test carefully before pushing any update.
|
||||
Apps compiled with :ref:`CONFIG_ESP_SYSTEM_ESP32_SRAM1_REGION_AS_IRAM` may fail to boot, if used together with a software bootloader that was compiled before this config option was introduced. If you are using an older bootloader and updating over OTA, please test carefully before pushing any updates.
|
||||
|
||||
Any memory which ends up not being used for static IRAM will be added to the heap.
|
||||
Any memory that ends up unused for static IRAM will be added to the heap.
|
||||
|
||||
.. only:: esp32c3
|
||||
|
||||
Flash Suspend Feature
|
||||
^^^^^^^^^^^^^^^^^^^^^
|
||||
|
||||
When using ESP Flash APIs and other APIs based on the former (NVS, Partition APIs, etc.), the Cache will be disabled. During this period of time, any code executed must reside in internal RAM (see :ref:`concurrency-constraints-flash`). Hence, interrupt handlers that are not in internal RAM will not be executed.
|
||||
When using SPI flash driver API and other APIs based on the former (NVS, Partition APIs, etc.), the Cache will be disabled. During this period, any code executed must reside in internal RAM, see :ref:`concurrency-constraints-flash`. Hence, interrupt handlers that are not in internal RAM will not be executed.
|
||||
|
||||
To achieve this, ESP-IDF Drivers usually have the following two options:
|
||||
- an option to place the driver's internal ISR handler in internal RAM
|
||||
- an option to place some control functions in internal RAM.
|
||||
To achieve this, ESP-IDF drivers usually have the following two options:
|
||||
|
||||
User ISR callbacks (and involved variables) have to be in internal RAM if they are also used in interrupt contexts.
|
||||
- Place the driver's internal ISR handler in the internal RAM.
|
||||
- Place some control functions in the internal RAM.
|
||||
|
||||
Placing additional code into IRAM will exacerbate the IRAM usage. For this reason, there is :ref:`CONFIG_SPI_FLASH_AUTO_SUSPEND`, which can alleviate the aforementioned kinds of IRAM usage. By enabling this feature, cache won't be disabled when ESP Flash and ESP-Flash-based APIs are used. Therefore, code and data in Flash can be executed or accessed normally, but with some minor delay. See :ref:`Flash Auto Suspend <auto-suspend>` for more details about this feature.
|
||||
User ISR callbacks and involved variables have to be in internal RAM if they are also used in interrupt contexts.
|
||||
|
||||
Regarding the flash suspend feature usage, and corresponding response time delay, please also see this example :example:`system/flash_suspend` .
|
||||
Placing additional code into IRAM will exacerbate IRAM usage. For this reason, there is :ref:`CONFIG_SPI_FLASH_AUTO_SUSPEND`, which can alleviate the aforementioned kinds of IRAM usage. By enabling this feature, the Cache will not be disabled when SPI flash driver APIs and SPI flash driver-based APIs are used. Therefore, code and data in flash can be executed or accessed normally, but with some minor delay. See :ref:`auto-suspend` for more details about this feature.
|
||||
|
||||
Regarding the flash suspend feature usage, and corresponding response time delay, please also see this example :example:`system/flash_suspend`.
|
||||
|
||||
|
||||
.. only:: esp32
|
||||
@@ -189,7 +206,7 @@ The following options will reduce IRAM usage of some ESP-IDF features:
|
||||
Putting C Library in Flash
|
||||
^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
||||
When compiling for ESP32 revisions older than ECO3 (:ref:`CONFIG_ESP32_REV_MIN`), PSRAM cache bug workaround (:ref:`CONFIG_SPIRAM_CACHE_WORKAROUND`) option is enabled, and the C library functions normally located in ROM are recompiled with the workaround and placed into IRAM instead. For most applications, it is safe to move many of the C library functions into Flash, reclaiming some IRAM. Corresponding options include:
|
||||
When compiling for ESP32 revisions older than ECO3 (:ref:`CONFIG_ESP32_REV_MIN`), the PSRAM Cache bug workaround (:ref:`CONFIG_SPIRAM_CACHE_WORKAROUND`) option is enabled, and the C library functions normally located in ROM are recompiled with the workaround and placed into IRAM instead. For most applications, it is safe to move many of the C library functions into flash, reclaiming some IRAM. Corresponding options include:
|
||||
|
||||
.. list::
|
||||
|
||||
@@ -203,10 +220,10 @@ The following options will reduce IRAM usage of some ESP-IDF features:
|
||||
- :ref:`CONFIG_SPIRAM_CACHE_LIBSTR_IN_IRAM`: affects the functions ``strcasecmp``, ``strcasestr``, ``strchr``, ``strcoll``, ``strcpy``, ``strcspn``, ``strdup``, ``strdup_r``, ``strlcat``, ``strlcpy``, ``strlen``, ``strlwr``, ``strncasecmp``, ``strncat``, ``strncmp``, ``strncpy``, ``strndup``, ``strndup_r``, ``strrchr``, ``strsep``, ``strspn``, ``strstr``, ``strtok_r, and ``strupr``.
|
||||
- :ref:`CONFIG_SPIRAM_CACHE_LIBRAND_IN_IRAM`: affects the functions ``srand``, ``rand``, and ``rand_r``.
|
||||
- :ref:`CONFIG_SPIRAM_CACHE_LIBENV_IN_IRAM`: affects the functions ``environ``, ``envlock``, and ``getenv_r``.
|
||||
- :ref:`CONFIG_SPIRAM_CACHE_LIBFILE_IN_IRAM`: affects the functions lock``, ``isatty``, ``fclose``, ``open``, ``close``, ``creat``, ``read``, ``rshift``, ``sbrk``, ``stdio``, ``syssbrk``, ``sysclose``, ``sysopen``, ``creat``, ``sysread``, ``syswrite``, ``impure``, ``fwalk``, and ``findfp``.
|
||||
- :ref:`CONFIG_SPIRAM_CACHE_LIBFILE_IN_IRAM`: affects the functions ``lock``, ``isatty``, ``fclose``, ``open``, ``close``, ``creat``, ``read``, ``rshift``, ``sbrk``, ``stdio``, ``syssbrk``, ``sysclose``, ``sysopen``, ``creat``, ``sysread``, ``syswrite``, ``impure``, ``fwalk``, and ``findfp``.
|
||||
- :ref:`CONFIG_SPIRAM_CACHE_LIBMISC_IN_IRAM`: affects the functions ``raise`` and ``system``.
|
||||
|
||||
The exact amount of IRAM saved will depend on how much C library code is actually used by the application. In addition to these, the following options may be used to move more of the C library code into Flash, however note that this may result in reduced performance. Also take care to not use corresponding C library functions from interrupts which may be called while cache is disabled (allocated with :c:macro:`ESP_INTR_FLAG_IRAM` flag), refer to :ref:`iram-safe-interrupt-handlers` for more details. For these reasons, the functions ``itoa``, ``memcmp``, ``memcpy``, ``memset``, ``strcat``, ``strcmp``, and ``strlen`` are always put in IRAM.
|
||||
The exact amount of IRAM saved will depend on how much C library code is actually used by the application. In addition, the following options may be used to move more of the C library code into flash, however note that this may result in reduced performance. Be careful not to use the C library function allocated with :c:macro:`ESP_INTR_FLAG_IRAM` flag from interrupts when cache is disabled, refer to :ref:`iram-safe-interrupt-handlers` for more details. For these reasons, the functions ``itoa``, ``memcmp``, ``memcpy``, ``memset``, ``strcat``, ``strcmp``, and ``strlen`` are always put in IRAM.
|
||||
|
||||
.. note::
|
||||
|
||||
|
||||
Reference in New Issue
Block a user