linux-kernel - Re: [PATCH v2 1/5] blk-mq-sched: introduce high level elevator lock

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]

Message-ID: <05c6e25d-4c61-417d-b916-7e91f5195b39@suse.de>
Date: Thu, 31 Jul 2025 08:17:05 +0200
From: Hannes Reinecke <hare@...e.de>
To: Yu Kuai <yukuai1@...weicloud.com>, dlemoal@...nel.org, jack@...e.cz,
 tj@...nel.org, josef@...icpanda.com, axboe@...nel.dk, yukuai3@...wei.com
Cc: cgroups@...r.kernel.org, linux-block@...r.kernel.org,
 linux-kernel@...r.kernel.org, yi.zhang@...wei.com, yangerkun@...wei.com,
 johnny.chenyi@...wei.com
Subject: Re: [PATCH v2 1/5] blk-mq-sched: introduce high level elevator lock

On 7/30/25 10:22, Yu Kuai wrote:
> From: Yu Kuai <yukuai3@...wei.com>
> 
> Currently, both mq-deadline and bfq have global spin lock that will be
> grabbed inside elevator methods like dispatch_request, insert_requests,
> and bio_merge. And the global lock is the main reason mq-deadline and
> bfq can't scale very well.
> 
> While dispatching request, blk_mq_get_disatpch_budget() and
> blk_mq_get_driver_tag() must be called, and they are not ready to be called
> inside elevator methods, hence introduce a new method like
> dispatch_requests is not possible.
> 
> Hence introduce a new high level elevator lock, currently it is protecting
> dispatch_request only. Following patches will convert mq-deadline and bfq
> to use this lock and finally support request batch dispatching by calling
> the method multiple time while holding the lock.
> 
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
> ---
>   block/blk-mq-sched.c | 6 ++++++
>   block/elevator.c     | 1 +
>   block/elevator.h     | 4 ++--
>   3 files changed, 9 insertions(+), 2 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@...e.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@...e.de                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich