lkml.org 
[lkml]   [2017]   [Oct]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH V6 5/5] blk-mq-sched: don't dequeue request until all in ->dispatch are flushed
On Mon, Oct 09, 2017 at 07:24:24PM +0800, Ming Lei wrote:
> During dispatching, we moved all requests from hctx->dispatch to
> one temporary list, then dispatch them one by one from this list.
> Unfortunately during this period, run queue from other contexts
> may think the queue is idle, then start to dequeue from sw/scheduler
> queue and still try to dispatch because ->dispatch is empty. This way
> hurts sequential I/O performance because requests are dequeued when
> lld queue is busy.
>
> This patch introduces the state of BLK_MQ_S_DISPATCH_BUSY to
> make sure that request isn't dequeued until ->dispatch is
> flushed.
>
> Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

I think this will do for now.

Reviewed-by: Omar Sandoval <osandov@fb.com>

> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
> block/blk-mq-debugfs.c | 1 +
> block/blk-mq-sched.c | 38 ++++++++++++++++++++++++++++++++------
> block/blk-mq.c | 5 +++++
> include/linux/blk-mq.h | 1 +
> 4 files changed, 39 insertions(+), 6 deletions(-)

\
 
 \ /
  Last update: 2017-10-10 20:27    [W:0.107 / U:0.052 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site