On 7/2/20 11:25 PM, Song Liu wrote:
On Thu, Jul 2, 2020 at 7:29 AM Artur Paszkiewicz <artur.paszkiewicz@xxxxxxxxx> wrote:Use generic io accounting functions to manage io stats. There was an attempt to do this earlier in commit 18c0b223cf99 ("md: use generic io stats accounting functions to simplify io stat accounting"), but it did not include a call to generic_end_io_acct() and caused issues with tracking in-flight IOs, so it was later removed in commit 74672d069b29 ("md: fix md io stats accounting broken"). This patch attempts to fix this by using both bio_start_io_acct() and bio_end_io_acct(). To make it possible, a struct md_io is allocated for every new md bio, which includes the io start_time. A new mempool is introduced for this purpose. We override bio->bi_end_io with our own callback and call bio_start_io_acct() before passing the bio to md_handle_request(). When it completes, we call bio_end_io_acct() and the original bi_end_io callback. This adds correct statistics about in-flight IOs and IO processing time, interpreted e.g. in iostat as await, svctm, aqu-sz and %util. It also fixes a situation where too many IOs where reported if a bio was re-submitted to the mddev, because io accounting is now performed only on newly arriving bios. Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@xxxxxxxxx>Thanks Artur and Guoqing! I run quick test with this. Seems it only adds proper statistics to raid5 array, but not to raid0 array. Is this expected?
Because bio_endio is not called, and it is same for linear and faulty. I think we have to clone bio for them ..., then it is better to do the job in the personality layer. 1. For md-multipath, raid1 and raid10, track start time by change the multipath_bh, r1bio and r10bio. 2. For raid5, override the bi_end_io like this. 3. Then other personalities have to clone bio ... Thanks, Guoqing
