linux-kernel - Re: [PATCHv6 1/1] block: introduce content activity based ioprio

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Date: Thu, 1 Feb 2024 12:05:23 +0800
From: Zhaoyang Huang <huangzhaoyang@...il.com>
To: Matthew Wilcox <willy@...radead.org>
Cc: "zhaoyang.huang" <zhaoyang.huang@...soc.com>, Andrew Morton <akpm@...ux-foundation.org>, 
	Jens Axboe <axboe@...nel.dk>, Yu Zhao <yuzhao@...gle.com>, Damien Le Moal <dlemoal@...nel.org>, 
	Niklas Cassel <niklas.cassel@....com>, "Martin K . Petersen" <martin.petersen@...cle.com>, 
	Hannes Reinecke <hare@...e.de>, Linus Walleij <linus.walleij@...aro.org>, linux-mm@...ck.org, 
	linux-block@...r.kernel.org, linux-fsdevel@...r.kernel.org, 
	linux-kernel@...r.kernel.org, steve.kang@...soc.com
Subject: Re: [PATCHv6 1/1] block: introduce content activity based ioprio

On Thu, Feb 1, 2024 at 10:39 AM Zhaoyang Huang <huangzhaoyang@...ilcom> wrote:
>
> On Wed, Jan 31, 2024 at 9:23 PM Matthew Wilcox <willy@...radead.org> wrote:
> >
> > On Wed, Jan 31, 2024 at 06:59:12PM +0800, zhaoyang.huang wrote:
> > > change of v6: replace the macro of bio_add_xxx by submit_bio which
> > >               iterating the bio_vec before launching bio to block layer
> >
> > Still wrong.
> I did some research on bio operations in the system and state my
> understanding here. I would like to have you review it and give me
> more details of the fault. thanks
>
> 1. REQ_OP_ZONE_xxx
> a. These operations are from driver/block layer/fs where we can keep
> driver/block layer using the legacy submit_bio by not including
> act_prio.h.
> b. most of fs's REQ_OP_ZONE_xxx will be handled by blkdev_zone_mgmt
> which is the same as 'a'
> c. __submit_zone_reset_cmd within f2fs use no page for REQ_OP_ZONE_RESET
>
> 2. other REQ_OP_<none>_READ/WRITE except REQ_OP_ZONE_xxx
> These operations all comes from driver and block layer as same as 1.a
>
> 3. direct_io
> keep fs/direct-io.c and fs/iomap/direct-io.c using legacy submit_bio
>
> 4. metadata, dentry
> Are these data also file pages?
>
> 5. normal REQ_OP_READ/WRITE/SYNC
> fs choose to use act based submit_bio by including act_ioprio.h in
> corresponding c file

OR could I restrict the change by judging bio_op as below

+ if (bio_op(bio) == REQ_OP_READ || bio_op(bio) == REQ_OP_WRITE)
+ {
       class = IOPRIO_PRIO_CLASS(bio->bi_ioprio);
       level = IOPRIO_PRIO_LEVEL(bio->bi_ioprio);
       hint = IOPRIO_PRIO_HINT(bio->bi_ioprio);
       bio_for_each_bvec(bv, bio, iter) {
               page = bv.bv_page;
               activity += PageWorkingset(page) ? 1 : 0;
               cnt++;
       }
       if (activity >= cnt / 2)
               class = IOPRIO_CLASS_RT;
       else if (activity >= cnt / 4)
               class = max(IOPRIO_PRIO_CLASS(get_current_ioprio()),
IOPRIO_CLASS_BE);
       bio->bi_ioprio = IOPRIO_PRIO_VALUE_HINT(class, level, hint);
+ }
       submit_bio(bio);