linux-kernel - Re: [patch 4/4] blk-mq: switch to percpu-ida for tag menagement

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: <52580B26.2090508@kernel.dk>
Date:	Fri, 11 Oct 2013 08:28:54 -0600
From:	Jens Axboe <axboe@...nel.dk>
To:	Shaohua Li <shli@...nel.org>, linux-kernel@...r.kernel.org
CC:	kmo@...erainc.com
Subject: Re: [patch 4/4] blk-mq: switch to percpu-ida for tag menagement

On 10/11/2013 01:18 AM, Shaohua Li wrote:
> Using percpu-ida to manage blk-mq tags. the percpu-ida has similar algorithm
> like the blk-mq-tag. The difference is when a cpu can't allocate tags
> blk-mq-tag uses ipi to purge remote cpu cache and percpu-ida directly purges
> remote cpu cache. In practice (testing null_blk), the percpu-ida approach is
> much faster when total tags aren't enough.

I'm not surprised it's a lot faster the the pathological case of needing
to prune tags, the IPI isn't near ideal for that. I'm assuming the
general performance is the same for the non-full case?

-- 
Jens Axboe

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/