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From: Jens Axboe <axboe@suse.de>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Andrew Morton <akpm@osdl.org>,
	linux-kernel@vger.kernel.org, kenneth.w.chen@intel.com
Subject: Re: [patch 6/9] blk: unplug later
Date: Wed, 13 Apr 2005 12:20:36 +0200	[thread overview]
Message-ID: <20050413102030.GO20044@suse.de> (raw)
In-Reply-To: <425C7691.80605@yahoo.com.au>

On Wed, Apr 13 2005, Nick Piggin wrote:
> Andrew Morton wrote:
> >Nick Piggin <nickpiggin@yahoo.com.au> wrote:
> >
> >>get_request_wait needn't unplug the device immediately.
> >
> >
> >Probably.  But what if the get_request(q, rw, GFP_NOIO); did
> >some sleeping?
> >
> 
> It can't sleep unless it returns the request, because it
> is using mempool allocs. So any time it returns NULL, it
> hasn't slept.
> 
> But Jens would have a better idea of the correct behaviour.
> Jens, what do you think?

I think the patch makes sense. Additionally, it looks safer to unplug in
the loop as well - not just as an optimization for the first run, but
further loops of the code may need to trigger an unplug of the queue.

-- 
Jens Axboe


  reply	other threads:[~2005-04-13 10:21 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-04-12 12:43 [patch 0/9] various (mainly mempool fixes and block layer improvements) Nick Piggin
2005-04-12 12:48 ` [patch 1/9] GFP_ZERO fix Nick Piggin
2005-04-12 19:47   ` Andrew Morton
2005-04-13  1:02     ` Nick Piggin
2005-04-14 10:59     ` Manfred Spraul
2005-04-12 12:48 ` [patch 2/9] mempool gfp flag Nick Piggin
2005-04-12 19:50   ` Andrew Morton
2005-04-13  1:03     ` Nick Piggin
2005-04-12 12:49 ` [patch 3/9] no PF_MEMALLOC tinkering Nick Piggin
2005-04-12 19:57   ` Andrew Morton
2005-04-13  1:13     ` Nick Piggin
2005-04-12 12:49 ` [patch 4/9] blk: no memory barrier Nick Piggin
2005-04-12 12:50 ` [patch 5/9] blk: branch hints Nick Piggin
2005-04-12 12:50 ` [patch 6/9] blk: unplug later Nick Piggin
2005-04-12 19:58   ` Andrew Morton
2005-04-13  1:32     ` Nick Piggin
2005-04-13 10:20       ` Jens Axboe [this message]
2005-04-12 12:51 ` [patch 7/9] blk: efficiency improvements Nick Piggin
2005-04-12 12:52 ` [patch 0/9] blk: reduce locking Nick Piggin
2005-04-12 12:53 ` [patch doh/9] mempool simplify alloc Nick Piggin

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