linux-kernel - Re: [PATCH v12 0/3] bio: control bio max size

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Date:   Fri, 04 Jun 2021 14:41:54 +0800
From:   Can Guo <cang@...eaurora.org>
To:     Changheun Lee <nanich.lee@...sung.com>
Cc:     Johannes.Thumshirn@....com, alex_y_xu@...oo.ca,
        asml.silence@...il.com, axboe@...nel.dk, bgoncalv@...hat.com,
        jejb@...ux.ibm.com, martin.petersen@...cle.com,
        avri.altman@....com, alim.akhtar@...sung.com, bvanassche@....org,
        damien.lemoal@....com, gregkh@...uxfoundation.org,
        hch@...radead.org, jaegeuk@...nel.org, linux-block@...r.kernel.org,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        ming.lei@...hat.com, osandov@...com, patchwork-bot@...nel.org,
        tj@...nel.org, tom.leiming@...il.com, yi.zhang@...hat.com,
        jisoo2146.oh@...sung.com, junho89.kim@...sung.com,
        mj0123.lee@...sung.com, seunghwan.hyun@...sung.com,
        sookwan7.kim@...sung.com, woosung2.lee@...sung.com,
        yt0928.kim@...sung.com
Subject: Re: [PATCH v12 0/3] bio: control bio max size

On 2021-06-04 13:03, Changheun Lee wrote:
> bio size can grow up to 4GB after muli-page bvec has been enabled.
> But sometimes large size of bio would lead to inefficient behaviors.
> Control of bio max size will be helpful to improve inefficiency.
> 
> blk_queue_max_bio_bytes() is added to enable be set the max_bio_bytes 
> in
> each driver layer. And max_bio_bytes sysfs is added to show current
> max_bio_bytes for each request queue.
> bio size can be controlled via max_bio_bytes.
> 

This is interesting, and we also noticed it right after multi-page bvec
is enabled since last year. Internally, we had a hack to disable it.
But it is good to have a tunable to control it. Thanks for the change.

Reviewed-by: Can Guo <cang@...eaurora.org>

> Changheun Lee (3):
>   bio: control bio max size
>   blk-sysfs: add max_bio_bytes
>   ufs: set max_bio_bytes with queue max sectors
> 
>  Documentation/ABI/testing/sysfs-block | 10 ++++++++++
>  Documentation/block/queue-sysfs.rst   |  7 +++++++
>  block/bio.c                           | 17 ++++++++++++++---
>  block/blk-settings.c                  | 19 +++++++++++++++++++
>  block/blk-sysfs.c                     |  7 +++++++
>  drivers/scsi/ufs/ufshcd.c             |  5 +++++
>  include/linux/bio.h                   |  4 +++-
>  include/linux/blkdev.h                |  3 +++
>  8 files changed, 68 insertions(+), 4 deletions(-)