From: Andrea Arcangeli <andrea@suse.de>
To: Jens Axboe <axboe@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
Marcelo Tosatti <marcelo@conectiva.com.br>,
Chris Mason <mason@suse.com>, lkml <linux-kernel@vger.kernel.org>,
"Stephen C. Tweedie" <sct@redhat.com>,
Jeff Garzik <jgarzik@pobox.com>, Andrew Morton <akpm@digeo.com>,
Alexander Viro <viro@math.psu.edu>
Subject: Re: RFC on io-stalls patch
Date: Wed, 16 Jul 2003 14:43:55 +0200 [thread overview]
Message-ID: <20030716124355.GE4978@dualathlon.random> (raw)
In-Reply-To: <20030715112737.GQ833@suse.de>
On Tue, Jul 15, 2003 at 01:27:37PM +0200, Jens Axboe wrote:
> On Tue, Jul 15 2003, Alan Cox wrote:
> > On Maw, 2003-07-15 at 06:26, Jens Axboe wrote:
> > > Sorry, but I think that is nonsense. This is the way we have always
> > > worked. You just have to maintain a decent queue length still (like we
> > > always have in 2.4) and there are no problems.
> >
> > The memory pinning problem is still real - and always has been. It shows up
> > best not on IDE disks but large slow media like magneto opticals where you
> > can queue lots of I/O but you get 500K/second
>
> Not the same thing. On slow media, like dvd-ram, what causes the problem
> is that you can dirty basically all of the RAM in the system. That has
> nothing to do with memory pinned in the request queue.
you can trivially bound the amount of dirty memory to nearly 0% with the
bdflush sysctl. And the overkill size of the queue until pre3 could be
an huge VM overhead compared to the dirty memory on lowmem boxes,
example a 32/64M machine. So I disagree it's only a mistake of write
throttling that gives problems on slow media.
Infact I tend to think the biggest problem for slow media in 2.4 is the
lack of per spindle pdflush.
Andrea
next prev parent reply other threads:[~2003-07-16 12:29 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-07-08 20:06 RFC on io-stalls patch Marcelo Tosatti
2003-07-10 13:57 ` Jens Axboe
2003-07-11 14:13 ` Chris Mason
2003-07-12 0:20 ` Nick Piggin
2003-07-12 18:37 ` Chris Mason
2003-07-12 7:37 ` Jens Axboe
2003-07-12 7:48 ` Jens Axboe
2003-07-12 18:32 ` Chris Mason
2003-07-13 0:33 ` Andrea Arcangeli
2003-07-13 9:01 ` Jens Axboe
2003-07-13 16:20 ` Chris Mason
2003-07-13 16:45 ` Jeff Garzik
2003-07-13 19:33 ` Andrea Arcangeli
2003-07-13 17:47 ` Jens Axboe
2003-07-13 19:35 ` Andrea Arcangeli
2003-07-14 0:36 ` Chris Mason
2003-07-13 19:19 ` Andrea Arcangeli
2003-07-14 5:49 ` Jens Axboe
2003-07-14 12:23 ` Marcelo Tosatti
2003-07-14 13:12 ` Jens Axboe
2003-07-14 19:51 ` Jens Axboe
2003-07-14 20:09 ` Chris Mason
2003-07-14 20:19 ` Andrea Arcangeli
2003-07-14 21:24 ` Chris Mason
2003-07-15 5:46 ` Jens Axboe
2003-07-14 20:09 ` Marcelo Tosatti
2003-07-14 20:24 ` Andrea Arcangeli
2003-07-14 20:34 ` Chris Mason
2003-07-15 5:35 ` Jens Axboe
[not found] ` <20030714224528.GU16313@dualathlon.random>
2003-07-15 5:40 ` Jens Axboe
[not found] ` <1058229360.13317.364.camel@tiny.suse.com>
2003-07-15 5:43 ` Jens Axboe
[not found] ` <20030714175238.3eaddd9a.akpm@osdl.org>
[not found] ` <20030715020706.GC16313@dualathlon.random>
2003-07-15 5:45 ` Jens Axboe
2003-07-15 6:01 ` Andrea Arcangeli
2003-07-15 6:08 ` Jens Axboe
2003-07-15 7:03 ` Andrea Arcangeli
2003-07-15 8:28 ` Jens Axboe
2003-07-15 9:12 ` Chris Mason
2003-07-15 9:17 ` Jens Axboe
2003-07-15 9:18 ` Jens Axboe
2003-07-15 9:30 ` Chris Mason
2003-07-15 10:03 ` Andrea Arcangeli
2003-07-15 10:11 ` Jens Axboe
2003-07-15 14:18 ` Chris Mason
2003-07-15 14:29 ` Jens Axboe
2003-07-16 17:06 ` Chris Mason
2003-07-15 9:22 ` Chris Mason
2003-07-15 9:59 ` Andrea Arcangeli
2003-07-15 9:48 ` Andrea Arcangeli
2003-07-14 20:16 ` Andrea Arcangeli
2003-07-14 20:17 ` Marcelo Tosatti
2003-07-14 20:27 ` Andrea Arcangeli
2003-07-15 5:26 ` Jens Axboe
2003-07-15 5:48 ` Andrea Arcangeli
2003-07-15 6:01 ` Jens Axboe
2003-07-15 6:33 ` Andrea Arcangeli
2003-07-15 11:22 ` Alan Cox
2003-07-15 11:27 ` Jens Axboe
2003-07-16 12:43 ` Andrea Arcangeli [this message]
2003-07-16 12:46 ` Jens Axboe
2003-07-16 12:59 ` Andrea Arcangeli
2003-07-16 13:04 ` Jens Axboe
2003-07-16 13:11 ` Andrea Arcangeli
2003-07-16 13:21 ` Jens Axboe
2003-07-16 13:44 ` Andrea Arcangeli
2003-07-16 14:00 ` Jens Axboe
2003-07-16 14:24 ` Andrea Arcangeli
2003-07-16 16:49 ` Andrew Morton
2003-07-15 18:47 Shane Shrybman
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