RE: [RFC PATCH 0/2] blk-mq I/O scheduling fixes

From: "Liu, Sunny" <ping.liu@lenovonetapp.com>
To: Hannes Reinecke <hare@suse.de>, Jens Axboe <axboe@kernel.dk>
Cc: "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	James Bottomley <james.bottomley@hansenpartnership.com>,
	Christoph Hellwig <hch@lst.de>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	Hans Holmberg <hans.holmberg@wdc.com>,
	Damien Le Moal <damien.lemoal@wdc.com>
Subject: RE: [RFC PATCH 0/2]  blk-mq I/O scheduling fixes
Date: Thu, 19 Sep 2019 09:56:45 +0000	[thread overview]
Message-ID: <BJXPR01MB02964BA1F5E67B7B6CB39EE7F4890@BJXPR01MB0296.CHNPR01.prod.partner.outlook.cn> (raw)
In-Reply-To: <20190919094547.67194-1-hare@suse.de>

Hello Sir,

I have a question about the I/O scheduler in kernel 5.2.9

in the new kernel, which I/O scheduler should be used by legacy rotating drive? Such as sata HDD?
During FIO testing with libaio, I had create multiple thread in the testing, and then found 512k and bigger sequent write had bad performance result. Even I had enable and use BFQ scheduler.

There has no sq scheduler anymore, only has none, mq-deadline, kyber and BFQ.
Mq-deadline and kyber is for fast block device. Only the BFQ looks better performance, but it can't keep the good behavior during 512k or bigger 100% seq write.

Could you give me some advices what parameter should I change for multiple thread bigger file seq writing?

Thanks all of you.

BestRegards,
SunnyLiu(刘萍)
LenovoNetApp 
北京市海淀区西北旺东路10号院2号楼L3-E1-01
L3-E1-01,Building No.2, Lenovo HQ West No.10 XiBeiWang East Rd.,
Haidian District, Beijing 100094, PRC
Tel: +86 15910622368

-----Original Message-----
From: linux-block-owner@vger.kernel.org <linux-block-owner@vger.kernel.org> On Behalf Of Hannes Reinecke
Sent: 2019年9月19日 17:46
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-scsi@vger.kernel.org; Martin K. Petersen <martin.petersen@oracle.com>; James Bottomley <james.bottomley@hansenpartnership.com>; Christoph Hellwig <hch@lst.de>; linux-block@vger.kernel.org; Hans Holmberg <hans.holmberg@wdc.com>; Damien Le Moal <damien.lemoal@wdc.com>; Hannes Reinecke <hare@suse.de>
Subject: [RFC PATCH 0/2] blk-mq I/O scheduling fixes

Hi all,

Damien pointed out that there are some areas in the blk-mq I/O scheduling algorithm which have a distinct legacy feel to it, and prohibit multiqueue I/O schedulers from working properly.
These two patches should clear up this situation, but as it's not quite clear what the original intention of the code was I'll be posting them as an RFC.

So as usual, comments and reviews are welcome.

Hannes Reinecke (2):
  blk-mq: fixup request re-insert in blk_mq_try_issue_list_directly()
  blk-mq: always call into the scheduler in blk_mq_make_request()

 block/blk-mq.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

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