Andrea Arcangeli d527caf22e mm: compaction: prevent kswapd compacting memory to reduce CPU usage ... This patch reverts 5a03b051 ("thp: use compaction in kswapd for GFP_ATOMIC order > 0") due to reports stating that kswapd CPU usage was higher and IRQs were being disabled more frequently. This was reported at http://www.spinics.net/linux/fedora/alsa-user/msg09885.html. Without this patch applied, CPU usage by kswapd hovers around the 20% mark according to the tester (Arthur Marsh: http://www.spinics.net/linux/fedora/alsa-user/msg09899.html). With this patch applied, it's around 2%. The problem is not related to THP which specifies __GFP_NO_KSWAPD but is triggered by high-order allocations hitting the low watermark for their order and waking kswapd on kernels with CONFIG_COMPACTION set. The most common trigger for this is network cards configured for jumbo frames but it's also possible it'll be triggered by fork-heavy workloads (order-1) and some wireless cards which depend on order-1 allocations. The symptoms for the user will be high CPU usage by kswapd in low-memory situations which could be confused with another writeback problem. While a patch like 5a03b051 may be reintroduced in the future, this patch plays it safe for now and reverts it. [mel@csn.ul.ie: Beefed up the changelog] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reported-by: Arthur Marsh <arthur.marsh@internode.on.net> Tested-by: Arthur Marsh <arthur.marsh@internode.on.net> Cc: <stable@kernel.org> [2.6.38.1] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2011-03-22 17:44:00 -07:00
..
acpi	PM: Remove CONFIG_PM_OPS	2011-03-15 00:43:15 +01:00
asm-generic	include/asm-generic/unistd.h: fix syncfs syscall number	2011-03-22 17:43:58 -07:00
crypto
drm	Merge remote branch 'intel/drm-intel-next' of ../drm-next into drm-core-next	2011-03-14 14:15:13 +10:00
keys	RxRPC: Fix v1 keys	2011-03-02 22:18:53 -08:00
linux	mm: compaction: prevent kswapd compacting memory to reduce CPU usage	2011-03-22 17:44:00 -07:00
math-emu
media	[media] v4l: Include linux/videodev2.h in media/v4l2-ctrls.h	2011-01-19 11:52:09 -02:00
mtd
net	IPVS: Use global mutex in ip_vs_app.c	2011-03-21 20:39:24 -07:00
pcmcia	pcmcia: re-enable Zoomed Video support	2011-02-20 12:47:34 +01:00
rdma	RDMA: Update workqueue usage	2011-01-16 21:16:31 -08:00
rxrpc
scsi	Merge git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6	2011-03-17 17:54:40 -07:00
sound	Merge branch 'topic/misc' into for-linus	2011-03-18 07:39:08 +01:00
target	[SCSI] target: Fix t_transport_aborted handling in LUN_RESET + active I/O shutdown	2011-02-28 11:23:32 -06:00
trace	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6	2011-03-18 10:46:37 -07:00
video	fbdev: sh_mobile_lcdc: Add YUV framebuffer support	2011-03-16 17:27:10 +09:00
xen	Merge branch 'stable/xen.pm.bug-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen	2011-03-17 18:37:42 -07:00
Kbuild