Re: [LKP] Re: [io_uring] 584b0180f0: phoronix-test-suite.fio.SequentialWrite.IO_uring.Yes.Yes.1MB.DefaultTestDirectory.mb_s -10.2% regression

[Yin Fengwei <fengwei.yin@intel.com>]

Hi Jens,

On 5/27/2022 9:50 PM, Jens Axboe wrote:
> I'm a bit skeptical on this, but I'd like to try and run the test case.
> Since it's just a fio test case, why can't I find it somewhere? Seems
> very convoluted to have to setup lkp-tests just for this. Besides, I
> tried, but it doesn't work on aarch64...
Recheck this regression report. The regression could be reproduced if
the following config file is used with fio (tag: fio-3.25) :

	[global]
	rw=write
	ioengine=io_uring
	iodepth=64
	size=1g
	direct=1
	buffered=1
	startdelay=5
	force_async=4
	ramp_time=5
	runtime=20
	time_based
	clat_percentiles=0
	disable_lat=1
	disable_clat=1
	disable_slat=1
	filename=test_fiofile
	[test]
	name=test
	bs=1M
	stonewall

Just FYI, a small change to commit: 584b0180f0f4d67d7145950fe68c625f06c88b10:

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 969f65de9972..616d857f8fc6 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3181,8 +3181,13 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
        struct kiocb *kiocb = &req->rw.kiocb;
        unsigned ioprio;
+       struct file *file = req->file;
        int ret;

+       if (likely(file && (file->f_mode & FMODE_WRITE)))
+               if (!io_req_ffs_set(req))
+                       req->flags |= io_file_get_flags(file) << REQ_F_SUPPORT_NOWAIT_BIT;
+
        kiocb->ki_pos = READ_ONCE(sqe->off);

        ioprio = READ_ONCE(sqe->ioprio);

could make regression gone. No idea how req->flags impact the write performance. Thanks.


Regards
Yin, Fengwei