RE: [Non-DoD Source] Re: [PATCH] blk-mq: allow 4x BLK_MAX_REQUEST_COUNT at blk_plug for multiple_queues

All,
I have a suspicion this will help my efforts increasing the IOPS ability of mdraid  in 10-12 NVMe drive  per raid group situations.

Pure neophyte question, which I apologize for in advance, how can I test this?   Does this end up in  a 5.15 release candidate kernel?

I want to make contributions wherever I can, as I have hardware and needs, so I can act as a performance validator within reason.   I know I can't make contributions as a developer, but I'm willing to contribute in areas where our goals are in alignment and this appears to be one.

Regards,
Jim


-----Original Message-----
From: Jens Axboe <axboe@kernel.dk> 
Sent: Tuesday, September 7, 2021 7:06 PM
To: Song Liu <redacted>; linux-block@vger.kernel.org; linux-raid@vger.kernel.org
Cc: marcin.wanat@gmail.com
Subject: [Non-DoD Source] Re: [PATCH] blk-mq: allow 4x BLK_MAX_REQUEST_COUNT at blk_plug for multiple_queues

On 9/7/21 5:03 PM, Song Liu wrote:

Limiting number of request to BLK_MAX_REQUEST_COUNT at blk_plug hurts 
performance for large md arrays. [1] shows resync speed of md array 
drops for md array with more than 16 HDDs.

Fix this by allowing more request at plug queue. The multiple_queue 
flag is used to only apply higher limit to multiple queue cases.

Applied, thanks.

--
Jens Axboe