From: Jens Axboe <axboe@kernel.dk>
To: Shaohua Li <shli@kernel.org>, linux-kernel@vger.kernel.org
Cc: kmo@daterainc.com
Subject: Re: [patch 4/4] blk-mq: switch to percpu-ida for tag menagement
Date: Fri, 11 Oct 2013 08:28:54 -0600 [thread overview]
Message-ID: <52580B26.2090508@kernel.dk> (raw)
In-Reply-To: <20131011072404.749268620@kernel.org>
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
next prev parent reply other threads:[~2013-10-11 14:29 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-11 7:18 [patch 0/4] blk-mq: use percpu_ida to manage tags Shaohua Li
2013-10-11 7:18 ` [patch 1/4] percpu_ida: make percpu_ida percpu size/batch configurable Shaohua Li
2013-10-11 20:31 ` Kent Overstreet
2013-10-12 0:52 ` Shaohua Li
2013-10-11 7:18 ` [patch 2/4] percpu_ida: add percpu_ida_for_each_free Shaohua Li
2013-10-11 20:34 ` Kent Overstreet
2013-10-11 7:18 ` [patch 3/4] percpu_ida: add an API to return free tags Shaohua Li
2013-10-11 20:35 ` Kent Overstreet
2013-10-12 1:02 ` Shaohua Li
2013-10-11 7:18 ` [patch 4/4] blk-mq: switch to percpu-ida for tag menagement Shaohua Li
2013-10-11 14:28 ` Jens Axboe [this message]
2013-10-12 0:49 ` Shaohua Li
2013-10-13 18:26 ` Jens Axboe
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