On 9/3/24 11:28 AM, Bart Van Assche wrote: > On 9/3/24 4:54 AM, ZhangHui wrote: >> 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 >> 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. >> >> Let's fixed this issue by moved non sync request completion flow to >> softirq, and keep the sync request completion in the top-half. > > An explanation is missing from the patch description why this issue > cannot be solved by changing rq_affinity to 2. And what's also missing is a changelog - to the poster, always include what's changed since the last version posted. Otherwise you just have 3 random patches posted and leave the discovery of why on earth there's now a v3 to the reader in having to pull in all 3 versions and see if the progression made sense. -- Jens Axboe
