linux-kernel - Re: [PATCH] virtio_blk: set the default scheduler to none

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 7 Dec 2023 06:53:59 +0000
From:   Chaitanya Kulkarni <chaitanyak@...dia.com>
To:     Li Feng <fengli@...rtx.com>, Jens Axboe <axboe@...nel.dk>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
        "open list:BLOCK LAYER" <linux-block@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:VIRTIO BLOCK AND SCSI DRIVERS" 
        <virtualization@...ts.linux.dev>
Subject: Re: [PATCH] virtio_blk: set the default scheduler to none

On 12/6/23 20:31, Li Feng wrote:
> virtio-blk is generally used in cloud computing scenarios, where the
> performance of virtual disks is very important. The mq-deadline scheduler
> has a big performance drop compared to none with single queue. In my tests,
> mq-deadline 4k readread iops were 270k compared to 450k for none. So here
> the default scheduler of virtio-blk is set to "none".
>
> Signed-off-by: Li Feng <fengli@...rtx.com>
> ---
>

This patch looks good to me, however I'd update the commit log and add
performance numbers for the non-mq case also, just in-case to show that we
are not breaking non-mq setup.

Being said that, in case we want to be future proof, we can also think of
adding a module param so if someone comes with a scenario where NO_SCHED is
not providing the performance then they can just use the module parameter
instead of again editing the code, irrespective of that :-

Reviewed-by: Chaitanya Kulkarni <kch@...dia.com>

-ck