Linux内核之IO栈解析

准备

操作

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sys_write -> vfs -> ext4 -> pagecache
     kworker -> [writeback](flush-xxx) -> wb_do_writeback -> writeback_sb_inodes -> do_writepages -> ext4_writepages -> submit_io
     ext4_writepages -> [jbd2/xxx](jbd2_journal)

generic_make_request -> blk_queue_bio   |  [kblockd] ---  __blk_run_queue -> request_fn

3. 驱动层： mmc_request_fn -> mmc_queue_thread(mmcqd/xxx) -> blk_fetch_request -> mmc_blk_issue_rq -> mmc_start_areq
    -> mmc_start_request (host:pre -> request -> post) --> sdhci_request -> sdhci_send_command
  优化： 1. 理论上可以合并数据后再写磁盘， 但这个目前还改不动

4. 硬件控制器： sdhci_send_command -> 写DMA数据以及寄存器(sdhci_prepare_data -> sdhci_writew) -> eMMC控制器

sdhci_irq -> mmc_request_done

效果