From: Frans Pop <elendil@planet.nl>
To: Mel Gorman <mel@csn.ul.ie>
Cc: Greg KH <gregkh@suse.de>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <cl@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: Memory management woes - order 1 allocation failures
Date: Fri, 12 Mar 2010 04:32:03 +0100 [thread overview]
Message-ID: <201003120432.06149.elendil@planet.nl> (raw)
In-Reply-To: <20100302222933.GF11355@csn.ul.ie>
On Tuesday 02 March 2010, Mel Gorman wrote:
> On Tue, Mar 02, 2010 at 10:17:51PM +0000, Alan Cox wrote:
> > > -#define TTY_BUFFER_PAGE ((PAGE_SIZE - 256) / 2)
> > > +#define TTY_BUFFER_PAGE (((PAGE_SIZE - sizeof(struct tty_buffer)) /
> > > 2) & ~0xFF)
> >
> > Yes agreed I missed a '-1'
>
> Frans, would you mind testing your NAS box with the following patch
> applied please? It should apply cleanly on top of 2.6.33-rc7. Thanks
Thanks Mel.
I've been running with this patch for about a week now and have so far not
seen any more allocation failures. I've tried doing large rsyncs a few
times.
It's not 100% conclusive, but I would say it improves things and I've
certainly not noticed any issues with the patch.
Before I got the patch I noticed that the default value for
vm.min_free_kbytes was only 1442 for this machine. Isn't that on the low
side? Could that have been a factor?
My concern is that, although fixing bugs in GFP_ATOMIC allocations is
certainly very good, I can't help wondering why the system does not keep a
bit more memory in reserve instead of using everything up for relatively
silly things like cache and buffers.
What if during an rsync I plug in some USB device whose driver has some
valid GFP_ATOMIC allocations? Shouldn't the memory manager allow for such
situations?
Cheers,
FJP
> tty: Keep the default buffering to sub-page units
>
> We allocate during interrupts so while our buffering is normally diced
> up small anyway on some hardware at speed we can pressure the VM
> excessively for page pairs. We don't really need big buffers to be
> linear so don't try so hard.
>
> In order to make this work well we will tidy up excess callers to
> request_room, which cannot itself enforce this break up.
>
> [mel@csn.ul.ie: Adjust TTY_BUFFER_PAGE to take padding into account]
> Signed-off-by: Alan Cox <alan@linux.intel.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Tested-by: Frans Pop <fjp@planet.nl>
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next prev parent reply other threads:[~2010-03-12 3:32 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-26 11:32 Memory management woes - order 1 allocation failures Frans Pop
2010-02-26 12:24 ` Frans Pop
2010-02-26 14:01 ` Pekka Enberg
2010-02-26 15:33 ` Frans Pop
2010-02-26 16:43 ` Christoph Lameter
2010-02-26 17:17 ` Pekka Enberg
2010-03-01 1:42 ` KOSAKI Motohiro
2010-03-02 17:26 ` Mel Gorman
2010-03-02 18:34 ` Alan Cox
2010-03-02 19:11 ` Mel Gorman
2010-03-02 19:29 ` Greg KH
2010-03-02 21:16 ` Mel Gorman
2010-03-02 22:17 ` Alan Cox
2010-03-02 22:29 ` Mel Gorman
2010-03-12 3:32 ` Frans Pop [this message]
2010-03-02 23:31 ` KOSAKI Motohiro
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