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< / div > < div class = "- topic/body concept/conbody body conbody" > < p class = "- topic/p p" data-ofbid = "d354393e22__20250121172132" > Mpp Heap 负责管理 mpp 中间件独占的 CMA 内存，并在 mpp 中间件需要物理内存时，将内存页面导出为 DMA-BUF。< / p > < section class = "- topic/section section" id = "mpp_heap_interface_intro__section_l31_nwh_d1c" data-ofbid = "mpp_heap_interface_intro__section_l31_nwh_d1c" > < h2 class = "- topic/title title sectiontitle" > mpp heap 特点< / h2 >
< p class = "- topic/p p" data-ofbid = "d354393e29__20250121172132" > < strong class = "+ topic/ph hi-d/b ph b" > 解决内存碎片化< / strong > < / p >
< p class = "- topic/p p" data-ofbid = "d354393e33__20250121172132" > CMA 内存允许多媒体模块和系统复用，在这种情况下，内存碎片化的情况不可避免（部分内存页面可能会被系统 pin 住，无法迁移）。而 mpp heap 管理的内存能确保只被
mpp 中间件使用，避免了内存页面被 pin 住而导致碎片化的问题。< / p >
< ul class = "- topic/ul ul" id = "mpp_heap_interface_intro__ul_m31_nwh_d1c" data-ofbid = "mpp_heap_interface_intro__ul_m31_nwh_d1c" > < li class = "- topic/li li" data-ofbid = "d354393e37__20250121172132" >
< p class = "- topic/p p" data-ofbid = "d354393e39__20250121172132" > mpp heap 的内存需要在用户态通过 < code class = "+ topic/ph pr-d/codeph ph codeph" > /dev/dmabuf/mpp< / code > 节点来申请，这个节点是 ArtInChip
平台扩展的私有节点，只有 mpp 中间件会访问。< / p >
< / li > < li class = "- topic/li li" data-ofbid = "d354393e45__20250121172132" >
< p class = "- topic/p p" data-ofbid = "d354393e47__20250121172132" > 对于系统来说，该块内存已被 alloc， ， < / p >
< / li > < / ul >
< div class = "- topic/note note tip note_tip" id = "mpp_heap_interface_intro__note_hsq_5wh_d1c" data-ofbid = "mpp_heap_interface_intro__note_hsq_5wh_d1c" > < span class = "note__title" > 提示：< / span >
< p class = "- topic/p p" data-ofbid = "d354393e53__20250121172132" > 只要在调用 mpp 中间件的过程中，只要做到资源的申请与释放一一对应，就能解决内存碎片化问题。< / p >
< / div >
< p class = "- topic/p p" data-ofbid = "d354393e58__20250121172132" > < strong class = "+ topic/ph hi-d/b ph b" > 允许系统回收 mpp heap 内存< / strong > < / p >
< p class = "- topic/p p" data-ofbid = "d354393e62__20250121172132" > mpp heap 管理的内存通过 < code class = "+ topic/ph pr-d/codeph ph codeph" > cma_alloc< / code > 申请，在系统内存资源紧张，而又不需要 mpp 中间件的情况下 （例如 OTA
升级），允许通过销毁 mpp heap 释放 CMA 内存给系统使用。< / p >
< div class = "- topic/note note note note_note" id = "mpp_heap_interface_intro__note_cbb_vwh_d1c" data-ofbid = "mpp_heap_interface_intro__note_cbb_vwh_d1c" > < span class = "note__title" > 注：< / span >
< p class = "- topic/p p" data-ofbid = "d354393e70__20250121172132" > mpp heap 一旦销毁，无法再次初始化，只能 reboot 系统。< / p >
< / div >
< / section > < section class = "- topic/section section" id = "mpp_heap_interface_intro__section_n31_nwh_d1c" data-ofbid = "mpp_heap_interface_intro__section_n31_nwh_d1c" > < h2 class = "- topic/title title sectiontitle" > mpp heap init< / h2 >
< p class = "- topic/p p" data-ofbid = "d354393e79__20250121172132" > 初始化时， < / p >
< figure class = "- topic/fig fig fignone" id = "mpp_heap_interface_intro__fig_o3p_twh_d1c" data-ofbid = "mpp_heap_interface_intro__fig_o3p_twh_d1c" > < br / > < div class = "imagecenter" > < img class = "- topic/image image imagecenter" id = "mpp_heap_interface_intro__image_o31_nwh_d1c" src = "../../../images/mpp/mpp_heap_init.png" alt = "mpp_heap_init" / > < / div > < br / > < figcaption data-caption-side = "bottom" class = "- topic/title title figcapcenter" > < span class = "figtitleprefix fig--title-label" > 图< span class = "fig--title-label-number" > 1< / span > < span class = "fig--title-label-punctuation" > . < / span > < / span > < span class = "fig--title" > mpp_heap 初始化< / span > < / figcaption > < / figure >
< / section > < section class = "- topic/section section" id = "mpp_heap_interface_intro__section_p31_nwh_d1c" data-ofbid = "mpp_heap_interface_intro__section_p31_nwh_d1c" > < h2 class = "- topic/title title sectiontitle" > mpp heap export< / h2 >
< p class = "- topic/p p" data-ofbid = "d354393e94__20250121172132" > mpp heap 通过 < code class = "+ topic/ph pr-d/codeph ph codeph" > /dev/dmabuf/mpp< / code > 节点，以 < code class = "+ topic/ph pr-d/codeph ph codeph" > ioctl< / code > 的方式将管理的 CMA
内存导出为标准的 DMA-BUF 文件句柄。< / p >
< p class = "- topic/p p" data-ofbid = "d354393e103__20250121172132" > genpool 内存池是一个基于 bitmap 的管理算法，其最小分配单位为 4K， < strong class = "+ topic/ph hi-d/b ph b" > 首地址< / strong > 还是 < strong class = "+ topic/ph hi-d/b ph b" > 大小< / strong > ，都遵循
< code class = "+ topic/ph pr-d/codeph ph codeph" > 4K< / code > 对齐。< / p >
< figure class = "- topic/fig fig fignone" id = "mpp_heap_interface_intro__fig_hcr_swh_d1c" data-ofbid = "mpp_heap_interface_intro__fig_hcr_swh_d1c" > < br / > < div class = "imagecenter" > < img class = "- topic/image image imagecenter" id = "mpp_heap_interface_intro__image_q31_nwh_d1c" src = "../../../images/mpp/mpp_heap_export.png" alt = "mpp_heap_export" / > < / div > < br / > < figcaption data-caption-side = "bottom" class = "- topic/title title figcapcenter" > < span class = "figtitleprefix fig--title-label" > 图< span class = "fig--title-label-number" > 2< / span > < span class = "fig--title-label-punctuation" > . < / span > < / span > < span class = "fig--title" > mpp_heap 导出 DMA-BUF< / span > < / figcaption > < / figure >
< / section > < section class = "- topic/section section" id = "mpp_heap_interface_intro__section_r31_nwh_d1c" data-ofbid = "mpp_heap_interface_intro__section_r31_nwh_d1c" > < h2 class = "- topic/title title sectiontitle" > mpp heap close< / h2 >
< p class = "- topic/p p" data-ofbid = "d354393e127__20250121172132" > 只需要 < code class = "+ topic/ph pr-d/codeph ph codeph" > close< / code > DMA-BUF 的文件句柄，即触发 mpp heap 的回收 DMA-BUF。< / p >
< div class = "- topic/note note note note_note" id = "mpp_heap_interface_intro__note_acy_rwh_d1c" data-ofbid = "mpp_heap_interface_intro__note_acy_rwh_d1c" > < span class = "note__title" > 注：< / span >
< p class = "- topic/p p" data-ofbid = "d354393e135__20250121172132" > 当一块 DMA-BUF 还被多媒体模块占用时， < / p >
< / div >
< figure class = "- topic/fig fig fignone" id = "mpp_heap_interface_intro__fig_lp3_rwh_d1c" data-ofbid = "mpp_heap_interface_intro__fig_lp3_rwh_d1c" > < br / > < div class = "imagecenter" > < img class = "- topic/image image imagecenter" id = "mpp_heap_interface_intro__image_s31_nwh_d1c" src = "../../../images/mpp/mpp_heap_close.png" alt = "mpp_heap_close" / > < / div > < br / > < figcaption data-caption-side = "bottom" class = "- topic/title title figcapcenter" > < span class = "figtitleprefix fig--title-label" > 图< span class = "fig--title-label-number" > 3< / span > < span class = "fig--title-label-punctuation" > . < / span > < / span > < span class = "fig--title" > mpp_heap 回收 DMA-BUF< / span > < / figcaption > < / figure >
< / section > < section class = "- topic/section section" id = "mpp_heap_interface_intro__section_t31_nwh_d1c" data-ofbid = "mpp_heap_interface_intro__section_t31_nwh_d1c" > < h2 class = "- topic/title title sectiontitle" > mpp heap destroy< / h2 >
< p class = "- topic/p p" data-ofbid = "d354393e151__20250121172132" > 通过 < code class = "+ topic/ph pr-d/codeph ph codeph" > /dev/dmabuf/mpp< / code > 节点，下发扩展的 < code class = "+ topic/ph pr-d/codeph ph codeph" > ioctl< / code > 接口即可销毁 MPP Heap,
将其中的 CMA 内存归还改系统。< / p >
< p class = "- topic/p p" data-ofbid = "d354393e160__20250121172132" > mpp heap 一旦被销毁，无法再次初始化，只能 reboot。< / p >
< figure class = "- topic/fig fig fignone" id = "mpp_heap_interface_intro__fig_ptm_qwh_d1c" data-ofbid = "mpp_heap_interface_intro__fig_ptm_qwh_d1c" > < br / > < div class = "imagecenter" > < img class = "- topic/image image imagecenter" id = "mpp_heap_interface_intro__image_u31_nwh_d1c" src = "../../../images/mpp/mpp_heap_destroy.png" alt = "mpp_heap_destroy" / > < / div > < br / > < figcaption data-caption-side = "bottom" class = "- topic/title title figcapcenter" > < span class = "figtitleprefix fig--title-label" > 图< span class = "fig--title-label-number" > 4< / span > < span class = "fig--title-label-punctuation" > . < / span > < / span > < span class = "fig--title" > mpp heap 销毁< / span > < / figcaption > < / figure >
< / section > < section class = "- topic/section section" id = "mpp_heap_interface_intro__section_v31_nwh_d1c" data-ofbid = "mpp_heap_interface_intro__section_v31_nwh_d1c" > < h2 class = "- topic/title title sectiontitle" > mpp heap 接口< / h2 >
< p class = "- topic/p p" data-ofbid = "d354393e175__20250121172132" > 接口如下 :< / p >
< pre class = "+ topic/pre pr-d/codeblock pre codeblock language-c" id = "mpp_heap_interface_intro__pre_w31_nwh_d1c" data-ofbid = "mpp_heap_interface_intro__pre_w31_nwh_d1c" > intdmabuf_device_open();voiddmabuf_device_close(intdma_fd);voiddmabuf_device_destroy(intdma_fd);intdmabuf_alloc(intdma_fd,intsize);< / pre >
< div class = "table-container" > < table class = "- topic/table table frame-all" id = "mpp_heap_interface_intro__table_x31_nwh_d1c" data-ofbid = "mpp_heap_interface_intro__table_x31_nwh_d1c" data-cols = "2" > < caption > < / caption > < colgroup > < col style = "width:50%" / > < col style = "width:50%" / > < / colgroup > < thead class = "- topic/thead thead" > < tr class = "- topic/row" > < th class = "- topic/entry entry colsep-1 rowsep-1" id = "mpp_heap_interface_intro__table_x31_nwh_d1c__entry__1" > 函数原型< / th > < th class = "- topic/entry entry colsep-0 rowsep-1" id = "mpp_heap_interface_intro__table_x31_nwh_d1c__entry__2" > int dmabuf_device_open()< / th > < / tr > < / thead > < tbody class = "- topic/tbody tbody" > < tr class = "- topic/row" > < td class = "- topic/entry entry colsep-1 rowsep-1" headers = "mpp_heap_interface_intro__table_x31_nwh_d1c__entry__1" > 功能说明< / td > < td class = "- topic/entry entry colsep-0 rowsep-1" headers = "mpp_heap_interface_intro__table_x31_nwh_d1c__entry__2" > 获取 mpp heap 的文件句柄< / td > < / tr > < tr class = "- topic/row" > < td class = "- topic/entry entry colsep-1 rowsep-1" headers = "mpp_heap_interface_intro__table_x31_nwh_d1c__entry__1" > 参数定义< / td > < td class = "- topic/entry entry colsep-0 rowsep-1" headers = "mpp_heap_interface_intro__table_x31_nwh_d1c__entry__2" > void< / td > < / tr > < tr class = "- topic/row" > < td class = "- topic/entry entry colsep-1 rowsep-1" headers = "mpp_heap_interface_intro__table_x31_nwh_d1c__entry__1" > 返回值< / td > < td class = "- topic/entry entry colsep-0 rowsep-1" headers = "mpp_heap_interface_intro__table_x31_nwh_d1c__entry__2" > dma_fd:成功< 0:失败< / td > < / tr > < tr class = "- topic/row" > < td class = "- topic/entry entry colsep-1 rowsep-0" headers = "mpp_heap_interface_intro__table_x31_nwh_d1c__entry__1" > 注意事项< / td > < td class = "- topic/entry entry colsep-0 rowsep-0" headers = "mpp_heap_interface_intro__table_x31_nwh_d1c__entry__2" > -< / td > < / tr > < / tbody > < / table > < / div >
< div class = "table-container" > < table class = "- topic/table table frame-all" id = "mpp_heap_interface_intro__table_y31_nwh_d1c" data-ofbid = "mpp_heap_interface_intro__table_y31_nwh_d1c" data-cols = "2" > < caption > < / caption > < colgroup > < col style = "width:25%" / > < col style = "width:75%" / > < / colgroup > < thead class = "- topic/thead thead" > < tr class = "- topic/row" > < th class = "- topic/entry entry colsep-1 rowsep-1" id = "mpp_heap_interface_intro__table_y31_nwh_d1c__entry__1" > 函数原型< / th > < th class = "- topic/entry entry colsep-0 rowsep-1" id = "mpp_heap_interface_intro__table_y31_nwh_d1c__entry__2" > void dmabuf_device_close(int dma_fd)< / th > < / tr > < / thead > < tbody class = "- topic/tbody tbody" > < tr class = "- topic/row" > < td class = "- topic/entry entry colsep-1 rowsep-1" headers = "mpp_heap_interface_intro__table_y31_nwh_d1c__entry__1" > 功能说明< / td > < td class = "- topic/entry entry colsep-0 rowsep-1" headers = "mpp_heap_interface_intro__table_y31_nwh_d1c__entry__2" > 释放 mpp heap 的文件句柄< / td > < / tr > < tr class = "- topic/row" > < td class = "- topic/entry entry colsep-1 rowsep-1" headers = "mpp_heap_interface_intro__table_y31_nwh_d1c__entry__1" > 参数定义< / td > < td class = "- topic/entry entry colsep-0 rowsep-1" headers = "mpp_heap_interface_intro__table_y31_nwh_d1c__entry__2" > dma_fd: mpp heap 的文件句柄< / td > < / tr > < tr class = "- topic/row" > < td class = "- topic/entry entry colsep-1 rowsep-1" headers = "mpp_heap_interface_intro__table_y31_nwh_d1c__entry__1" > 返回值< / td > < td class = "- topic/entry entry colsep-0 rowsep-1" headers = "mpp_heap_interface_intro__table_y31_nwh_d1c__entry__2" > void< / td > < / tr > < tr class = "- topic/row" > < td class = "- topic/entry entry colsep-1 rowsep-0" headers = "mpp_heap_interface_intro__table_y31_nwh_d1c__entry__1" > 注意事项< / td > < td class = "- topic/entry entry colsep-0 rowsep-0" headers = "mpp_heap_interface_intro__table_y31_nwh_d1c__entry__2" > -< / td > < / tr > < / tbody > < / table > < / div >
< div class = "table-container" > < table class = "- topic/table table frame-all" id = "mpp_heap_interface_intro__table_z31_nwh_d1c" data-ofbid = "mpp_heap_interface_intro__table_z31_nwh_d1c" data-cols = "2" > < caption > < / caption > < colgroup > < col style = "width:25%" / > < col style = "width:75%" / > < / colgroup > < thead class = "- topic/thead thead" > < tr class = "- topic/row" > < th class = "- topic/entry entry colsep-1 rowsep-1" id = "mpp_heap_interface_intro__table_z31_nwh_d1c__entry__1" > 函数原型< / th > < th class = "- topic/entry entry colsep-0 rowsep-1" id = "mpp_heap_interface_intro__table_z31_nwh_d1c__entry__2" > void dmabuf_device_destroy(int dma_fd)< / th > < / tr > < / thead > < tbody class = "- topic/tbody tbody" > < tr class = "- topic/row" > < td class = "- topic/entry entry colsep-1 rowsep-1" headers = "mpp_heap_interface_intro__table_z31_nwh_d1c__entry__1" > 功能说明< / td > < td class = "- topic/entry entry colsep-0 rowsep-1" headers = "mpp_heap_interface_intro__table_z31_nwh_d1c__entry__2" > 销毁 mpp heap< / td > < / tr > < tr class = "- topic/row" > < td class = "- topic/entry entry colsep-1 rowsep-1" headers = "mpp_heap_interface_intro__table_z31_nwh_d1c__entry__1" > 参数定义< / td > < td class = "- topic/entry entry colsep-0 rowsep-1" headers = "mpp_heap_interface_intro__table_z31_nwh_d1c__entry__2" > dma_fd: mpp heap 的文件句柄< / td > < / tr > < tr class = "- topic/row" > < td class = "- topic/entry entry colsep-1 rowsep-1" headers = "mpp_heap_interface_intro__table_z31_nwh_d1c__entry__1" > 返回值< / td > < td class = "- topic/entry entry colsep-0 rowsep-1" headers = "mpp_heap_interface_intro__table_z31_nwh_d1c__entry__2" > void< / td > < / tr > < tr class = "- topic/row" > < td class = "- topic/entry entry colsep-1 rowsep-0" headers = "mpp_heap_interface_intro__table_z31_nwh_d1c__entry__1" > 注意事项< / td > < td class = "- topic/entry entry colsep-0 rowsep-0" headers = "mpp_heap_interface_intro__table_z31_nwh_d1c__entry__2" > mpp heap 一旦被销毁，无法再次初始化，只能 reboot< / td > < / tr > < / tbody > < / table > < / div >
< div class = "table-container" > < table class = "- topic/table table frame-all" id = "mpp_heap_interface_intro__table_aj1_nwh_d1c" data-ofbid = "mpp_heap_interface_intro__table_aj1_nwh_d1c" data-cols = "2" > < caption > < / caption > < colgroup > < col style = "width:25%" / > < col style = "width:75%" / > < / colgroup > < thead class = "- topic/thead thead" > < tr class = "- topic/row" > < th class = "- topic/entry entry colsep-1 rowsep-1" id = "mpp_heap_interface_intro__table_aj1_nwh_d1c__entry__1" > 函数原型< / th > < th class = "- topic/entry entry colsep-0 rowsep-1" id = "mpp_heap_interface_intro__table_aj1_nwh_d1c__entry__2" > int dmabuf_alloc(int dma_fd, int size)< / th > < / tr > < / thead > < tbody class = "- topic/tbody tbody" > < tr class = "- topic/row" > < td class = "- topic/entry entry colsep-1 rowsep-1" headers = "mpp_heap_interface_intro__table_aj1_nwh_d1c__entry__1" > 功能说明< / td > < td class = "- topic/entry entry colsep-0 rowsep-1" headers = "mpp_heap_interface_intro__table_aj1_nwh_d1c__entry__2" > 通过 mpp heap 申请一块 DMA-BUF< / td > < / tr > < tr class = "- topic/row" > < td class = "- topic/entry entry colsep-1 rowsep-1" headers = "mpp_heap_interface_intro__table_aj1_nwh_d1c__entry__1" > 参数定义< / td > < td class = "- topic/entry entry colsep-0 rowsep-1" headers = "mpp_heap_interface_intro__table_aj1_nwh_d1c__entry__2" > dma_fd: mpp heap 的文件句柄 size: DMA-BUF size< / td > < / tr > < tr class = "- topic/row" > < td class = "- topic/entry entry colsep-1 rowsep-1" headers = "mpp_heap_interface_intro__table_aj1_nwh_d1c__entry__1" > 返回值< / td > < td class = "- topic/entry entry colsep-0 rowsep-1" headers = "mpp_heap_interface_intro__table_aj1_nwh_d1c__entry__2" > DMA-BUF fd:成功< 0:失败< / td > < / tr > < tr class = "- topic/row" > < td class = "- topic/entry entry colsep-1 rowsep-0" headers = "mpp_heap_interface_intro__table_aj1_nwh_d1c__entry__1" > 注意事项< / td > < td class = "- topic/entry entry colsep-0 rowsep-0" headers = "mpp_heap_interface_intro__table_aj1_nwh_d1c__entry__2" > -< / td > < / tr > < / tbody > < / table > < / div >
< / section > < section class = "- topic/section section" id = "mpp_heap_interface_intro__section_bj1_nwh_d1c" data-ofbid = "mpp_heap_interface_intro__section_bj1_nwh_d1c" > < h2 class = "- topic/title title sectiontitle" > mpp heap 设置< / h2 >
< p class = "- topic/p p" data-ofbid = "d354393e315__20250121172132" > mpp heap 管理的内存必须满足视频播放的最大需求。< / p >
< p class = "- topic/p p" data-ofbid = "d354393e318__20250121172132" > 视频播放内存可由 < a class = "- topic/xref xref" href = "../../../out/external-references/video_memory.html" > video memory< / a > 得到结果。< / p >
< p class = "- topic/p p" data-ofbid = "d354393e325__20250121172132" > mpp heap 中的内存从 CMA 预留内存中申请，但 CMA 内存不能只为 mpp heap 预留，还需要为
其他需要物理连续内存的模块预留，主要是显示，音频和通讯模块。< / p >
< p class = "- topic/p p" data-ofbid = "d354393e328__20250121172132" > 注解< / p >
< p class = "- topic/p p" data-ofbid = "d354393e332__20250121172132" > 如果 mpp heap 的 size 或 CMA 预留内存的 size 设置不合理，不仅影响 mpp heap 初始化，还可能影响其他模块运行。< / p >
< p class = "- topic/p p" data-ofbid = "d354393e335__20250121172132" > < strong class = "+ topic/ph hi-d/b ph b" > 显示模块< / strong > < / p >
< p class = "- topic/p p" data-ofbid = "d354393e339__20250121172132" > 以 fb0 为 32 位 argb8888 格式，外接分辨率为 1024x600 的 LCD 为例：< / p >
< p class = "- topic/p p" data-ofbid = "d354393e342__20250121172132" > 单 buffer 场景下需要 1024 * 600 * (32 / 8) = 2457600 byte, 约 < code class = "+ topic/ph pr-d/codeph ph codeph" > 2.4M< / code > CMA
内存< / p >
< p class = "- topic/p p" data-ofbid = "d354393e348__20250121172132" > 双 buffer 场景下则需要 < code class = "+ topic/ph pr-d/codeph ph codeph" > 4.8M< / code > < / p >
< p class = "- topic/p p" data-ofbid = "d354393e353__20250121172132" > < strong class = "+ topic/ph hi-d/b ph b" > 音频模块< / strong > < / p >
< p class = "- topic/p p" data-ofbid = "d354393e358__20250121172132" > 启用 ALSL 的场景下需要为音频模块预留 < code class = "+ topic/ph pr-d/codeph ph codeph" > 1.5M< / code > CMA 内存< / p >
< p class = "- topic/p p" data-ofbid = "d354393e364__20250121172132" > 在 ALSL 加 I2S 的场景下则需要 < code class = "+ topic/ph pr-d/codeph ph codeph" > 2.5M< / code > CMA 内存< / p >
< p class = "- topic/p p" data-ofbid = "d354393e370__20250121172132" > < strong class = "+ topic/ph hi-d/b ph b" > 通讯模块< / strong > < / p >
< p class = "- topic/p p" data-ofbid = "d354393e374__20250121172132" > WIFI, Bluetooth, USB 等通讯模块也会占用部分 CMA 内存，这个要根据实际场景进行推算。< / p >
< div class = "- topic/note note tip note_tip" id = "mpp_heap_interface_intro__note_rwl_mzh_d1c" data-ofbid = "mpp_heap_interface_intro__note_rwl_mzh_d1c" > < span class = "note__title" > 提示：< / span >
< p class = "- topic/p p" data-ofbid = "d354393e379__20250121172132" > CMA 预留内存的大小 ≥ mpp heap + 其他模块，同时 CMA 预留内存大小遵循 < code class = "+ topic/ph pr-d/codeph ph codeph" > 4M< / code > 对齐。
为确保系统正常运行，在设置 CMA 预留内存时要保有一定的余量。< / p >
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< div class = " wh_topic_toc " > < div class = "wh_topic_label" > 在本页上< / div > < ul > < li class = "section-item" > < div class = "section-title" > < a href = "#mpp_heap_interface_intro__section_l31_nwh_d1c" data-tocid = "mpp_heap_interface_intro__section_l31_nwh_d1c" > mpp heap 特点< / a > < / div > < / li > < li class = "section-item" > < div class = "section-title" > < a href = "#mpp_heap_interface_intro__section_n31_nwh_d1c" data-tocid = "mpp_heap_interface_intro__section_n31_nwh_d1c" > mpp heap init< / a > < / div > < / li > < li class = "section-item" > < div class = "section-title" > < a href = "#mpp_heap_interface_intro__section_p31_nwh_d1c" data-tocid = "mpp_heap_interface_intro__section_p31_nwh_d1c" > mpp heap export< / a > < / div > < / li > < li class = "section-item" > < div class = "section-title" > < a href = "#mpp_heap_interface_intro__section_r31_nwh_d1c" data-tocid = "mpp_heap_interface_intro__section_r31_nwh_d1c" > mpp heap close< / a > < / div > < / li > < li class = "section-item" > < div class = "section-title" > < a href = "#mpp_heap_interface_intro__section_t31_nwh_d1c" data-tocid = "mpp_heap_interface_intro__section_t31_nwh_d1c" > mpp heap destroy< / a > < / div > < / li > < li class = "section-item" > < div class = "section-title" > < a href = "#mpp_heap_interface_intro__section_v31_nwh_d1c" data-tocid = "mpp_heap_interface_intro__section_v31_nwh_d1c" > mpp heap 接口< / a > < / div > < / li > < li class = "section-item" > < div class = "section-title" > < a href = "#mpp_heap_interface_intro__section_bj1_nwh_d1c" data-tocid = "mpp_heap_interface_intro__section_bj1_nwh_d1c" > mpp heap 设置< / a > < / div > < / li > < / ul > < / div >
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