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Tue, 19 May 2026 06:31:09 -0700 (PDT) Date: Tue, 19 May 2026 14:31:08 +0100 From: Matt Fleming To: Jens Axboe Cc: Yu Kuai , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team , "yukuai (C)" Subject: Re: 10x I/O await times in 6.12 Message-ID: References: Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Apr 23, 2026 at 07:18:39PM +0100, Matt Fleming wrote: > On Mon, Apr 21, 2025 at 08:21:13PM +0800, Yu Kuai wrote: > > If nsecs - plug->cur_ktime is still milliseconds, can you check if > > the following patch can fix your problem? > > > > Thanks, > > Kuai > > > > diff --git a/block/blk-mq.c b/block/blk-mq.c > > index ae8494d88897..37197502147e 100644 > > --- a/block/blk-mq.c > > +++ b/block/blk-mq.c > > @@ -1095,7 +1095,9 @@ static inline void blk_account_io_start(struct request > > *req) > > return; > > > > req->rq_flags |= RQF_IO_STAT; > > - req->start_time_ns = blk_time_get_ns(); > > + > > + if (!current->plug) > > + req->start_time_ns = blk_time_get_ns(); > > > > /* > > * All non-passthrough requests are created from a bio with one > > @@ -2874,6 +2876,7 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, > > bool from_schedule) > > { > > struct request *rq; > > unsigned int depth; > > + u64 now; > > > > /* > > * We may have been called recursively midway through handling > > @@ -2887,6 +2890,10 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, > > bool from_schedule) > > depth = plug->rq_count; > > plug->rq_count = 0; > > > > + now = ktime_get_ns(); > > + rq_list_for_each(&plug->mq_list, rq) > > + rq->start_time_ns = now; > > + > > if (!plug->multiple_queues && !plug->has_elevator && !from_schedule) > > { > > struct request_queue *q; > > > > It's April again, and this time we're moving to 6.18. > > The I/O accounting bug reported at the start of this thread is still an > issue for us, and we've been carrying the above patch for 12 months. Hey Jens, any feedback on this patch?