From: Andrew Morton <akpm@linux-foundation.org>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Jeff Garzik <jgarzik@pobox.com>,
Jens Axboe <jens.axboe@oracle.com>,
LKML <linux-kernel@vger.kernel.org>,
Ian Campbell <Ian.Campbell@eu.citrix.com>
Subject: Re: [PATCH 5 of 5] xen: Avoid allocations causing swap activity on the resume path
Date: Sat, 31 May 2008 02:59:49 -0700 [thread overview]
Message-ID: <20080531025949.7c8b17bc.akpm@linux-foundation.org> (raw)
In-Reply-To: <48411F70.5020100@goop.org>
On Sat, 31 May 2008 10:50:40 +0100 Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> Does __GFP_HIGH necessarily mean that it won't try to
> do IO to push pages out?
Nope.
__GFP_FS: may enter filesystems
__GFP_IO: may perform IO
__GFP_IO also means "may do swapout". Even when swap is on a regular
file. This is because we do all the fs-related operations up-front
during swapon. So at alloc_pages()-time we can go direct-to-disk-blocks.
So I assume for this application you'll need GFP_NOIO. That's still
heaps better than GFP_ATOMIC, because it can sleep and wait for kswapd
to do stuff, and it can reclaim clean pagecache and clean swapcache.
Whether you should also add __GFP_HIGH to cause the page allocation to
bite harder into the page reserves is unclear to me, sorry.
next prev parent reply other threads:[~2008-05-31 10:00 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-31 0:01 [PATCH 0 of 5] xen device driver updates [resend] Jeremy Fitzhardinge
2008-05-31 0:01 ` [PATCH 1 of 5] xen/blkfront: Make sure we don't use bounce buffers, we don't need them Jeremy Fitzhardinge
2008-05-31 1:55 ` Jeff Garzik
2008-05-31 0:01 ` [PATCH 2 of 5] xn/blkfront: Add the CDROM_GET_CAPABILITY ioctl to blkfront Jeremy Fitzhardinge
2008-05-31 1:57 ` Jeff Garzik
2008-05-31 7:08 ` Jeremy Fitzhardinge
2008-05-31 0:01 ` [PATCH 3 of 5] xen/blkfront: Make sure that the device is fully ready before allowing release Jeremy Fitzhardinge
2008-05-31 0:01 ` [PATCH 4 of 5] xen/blkfront: add __exit to module_exit() handlers Jeremy Fitzhardinge
2008-05-31 1:57 ` Jeff Garzik
2008-05-31 0:01 ` [PATCH 5 of 5] xen: Avoid allocations causing swap activity on the resume path Jeremy Fitzhardinge
2008-05-31 1:58 ` Jeff Garzik
2008-05-31 9:50 ` Jeremy Fitzhardinge
2008-05-31 9:59 ` Andrew Morton [this message]
2008-05-31 10:10 ` Jeremy Fitzhardinge
2008-05-31 23:47 ` Andrew Morton
2008-06-01 0:38 ` Jeremy Fitzhardinge
2008-05-31 1:54 ` [PATCH 0 of 5] xen device driver updates [resend] Jeff Garzik
2008-05-31 6:31 ` Jeremy Fitzhardinge
-- strict thread matches above, loose matches on Subject: below --
2008-05-30 23:50 [PATCH 0 of 5] xen device driver updates Jeremy Fitzhardinge
2008-05-30 23:50 ` [PATCH 5 of 5] xen: Avoid allocations causing swap activity on the resume path Jeremy Fitzhardinge
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