From: Tejun Heo <htejun@gmail.com>
To: Shaohua Li <shaohua.li@intel.com>
Cc: lkml <linux-kernel@vger.kernel.org>,
Jens Axboe <jaxboe@fusionio.com>, Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [RFC]block: don't mark flush request as SOFTBARRIER
Date: Sun, 11 Sep 2011 11:51:28 +0900 [thread overview]
Message-ID: <20110911025128.GM29319@htj.dyndns.org> (raw)
In-Reply-To: <1315445394.29510.71.camel@sli10-conroe>
Hello,
On Thu, Sep 08, 2011 at 09:29:54AM +0800, Shaohua Li wrote:
> I'm wondering why flush request should be marked as
> SOFTBARRIER. Current flush sequence guarantees the correctness of
> flush even the request is reordered by ioscheduler.
The primary reason would be because when those flush data requests are
put on the dispatch queue, it doesn't go through elv_dispatch_sort().
SOFTBARRIERs function as dispatch sort boundaries and queueing flush
data request at the head w/o SOFTBARRIER would confuse dispatch
sorting, and we want to put it at the head of dispatch queue to
decrease latency for flush sequence.
Thanks.
--
tejun
next prev parent reply other threads:[~2011-09-11 2:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-08 1:29 Shaohua Li
2011-09-11 2:51 ` Tejun Heo [this message]
2011-09-13 1:04 ` Shaohua Li
2011-09-13 7:46 ` Tejun Heo
2011-09-14 6:04 ` Shaohua Li
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