From: David Chinner <dgc@sgi.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: Neil Brown <neilb@suse.de>, David Chinner <dgc@sgi.com>,
Andi Kleen <ak@suse.de>,
linux-kernel@vger.kernel.org, akpm@osdl.org
Subject: Re: RFC - how to balance Dirty+Writeback in the face of slow writeback.
Date: Mon, 28 Aug 2006 11:28:30 +1000 [thread overview]
Message-ID: <20060828012830.GH807830@melbourne.sgi.com> (raw)
In-Reply-To: <20060825063723.GO24258@kernel.dk>
On Fri, Aug 25, 2006 at 08:37:24AM +0200, Jens Axboe wrote:
> On Fri, Aug 25 2006, Neil Brown wrote:
>
> > I'm beginning to think that the current scheme really works very well
> > - except for a few 'bugs'(*).
>
> It works ok, but it makes it hard to experiment with larger queue depths
> when the vm falls apart :-). It's not a big deal, though, even if the
> design isn't very nice - nr_requests is not a well defined entity. It
> can be anywhere from 512b to megabyte(s) in size. So throttling on X
> number of requests tends to be pretty vague and depends hugely on the
> workload (random vs sequential IO).
So maybe we need a different control parameter - the amount of memory we
allow to be backed up in a queue rather than the number of requests the
queue can take...
Cheers,
Dave.
--
Dave Chinner
Principal Engineer
SGI Australian Software Group
next prev parent reply other threads:[~2006-08-28 1:28 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-14 23:40 RFC - how to balance Dirty+Writeback in the face of slow writeback Neil Brown
2006-08-15 8:06 ` Andrew Morton
2006-08-15 23:00 ` David Chinner
2006-08-17 4:08 ` Neil Brown
2006-08-17 6:14 ` Andrew Morton
2006-08-17 12:36 ` Trond Myklebust
2006-08-17 15:14 ` Andrew Morton
2006-08-17 16:22 ` Trond Myklebust
2006-08-18 5:49 ` Andrew Morton
2006-08-18 10:43 ` Nikita Danilov
2006-08-18 0:11 ` David Chinner
2006-08-18 6:29 ` Andrew Morton
2006-08-18 7:03 ` Jens Axboe
2006-08-18 7:11 ` Andrew Morton
2006-08-18 18:57 ` Andi Kleen
2006-08-21 0:35 ` Neil Brown
2006-08-21 3:15 ` David Chinner
2006-08-21 7:24 ` Neil Brown
2006-08-21 13:51 ` Jens Axboe
2006-08-25 4:36 ` Neil Brown
2006-08-25 6:37 ` Jens Axboe
2006-08-28 1:28 ` David Chinner [this message]
2006-08-25 13:16 ` Trond Myklebust
2006-08-27 8:21 ` Neil Brown
2006-08-21 14:28 ` David Chinner
2006-08-25 5:24 ` Neil Brown
2006-08-28 1:55 ` David Chinner
2006-08-21 7:47 ` Andi Kleen
2006-08-18 7:07 ` Neil Brown
2006-08-17 22:17 ` David Chinner
2006-08-17 3:59 ` Neil Brown
2006-08-17 6:22 ` Andrew Morton
2006-08-17 8:36 ` Jens Axboe
2006-08-17 13:21 ` Trond Myklebust
2006-08-17 15:30 ` Andrew Morton
2006-08-17 16:18 ` Trond Myklebust
2006-08-18 5:34 ` Andrew Morton
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