On Tue, Sep 03, 2024 at 07:54:37PM +0800, ZhangHui wrote: > From: zhanghui <zhanghui31@xxxxxxxxxx> > > Currently, for a controller that supports multiple queues, like UFS4.0, > the mq_ops->complete is executed in the interrupt top-half. Therefore, > the file system's end io is executed during the request completion process, > such as f2fs_write_end_io on smartphone. > > However, we found that the execution time of the file system end io > is strongly related to the size of the bio and the processing speed > of the CPU. Because the file system's end io will traverse every page > in bio, this is a very time-consuming operation. > > We measured that the 80M bio write operation on the little CPU will What is 80M bio? It is one known issue that soft lockup may be triggered in case of N:M blk-mq mapping, but not sure if that is the case. What is nr_hw_queues(blk_mq) and nr_cpus in your system? > cause the execution time of the top-half to be greater than 100ms. > The CPU tick on a smartphone is only 4ms, which will undoubtedly affect > scheduling efficiency. schedule is off too in softirq(bottom-half). > > Let's fixed this issue by moved non sync request completion flow to > softirq, and keep the sync request completion in the top-half. If you do care interrupt-off or schedule-off latency, you may have to move the IO handling into thread context in the driver. BTW, threaded irq can't help you too. Thanks, Ming
