]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
thp: disable transparent hugepages by default on small systems
authorRik van Riel <riel@redhat.com>
Thu, 13 Jan 2011 23:47:12 +0000 (15:47 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 14 Jan 2011 01:32:46 +0000 (17:32 -0800)
commit97562cd243298acf573620c764a1037bd545c9bc
tree79af6409724ae185e07bce4d9eaedef034bc83f8
parentc5a73c3d55be1faadba35b41a862e036a3b12ddb
thp: disable transparent hugepages by default on small systems

On small systems, the extra memory used by the anti-fragmentation memory
reserve and simply because huge pages are smaller than large pages can
easily outweigh the benefits of less TLB misses.

A less obvious concern is if run on a NUMA machine with asymmetric node
sizes and one of them is very small.  The reserve could make the node
unusable.

In case of the crashdump kernel, OOMs have been observed due to the
anti-fragmentation memory reserve taking up a large fraction of the
crashdump image.

This patch disables transparent hugepages on systems with less than 1GB of
RAM, but the hugepage subsystem is fully initialized so administrators can
enable THP through /sys if desired.

Signed-off-by: Rik van Riel <riel@redhat.com>
Acked-by: Avi Kiviti <avi@redhat.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/huge_memory.c