* [PATCH] register MADV_HUGEPAGE
@ 2010-01-16 18:46 Andrea Arcangeli
2010-01-17 11:08 ` Christoph Hellwig
0 siblings, 1 reply; 2+ messages in thread
From: Andrea Arcangeli @ 2010-01-16 18:46 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-kernel, linux-mm
From: Andrea Arcangeli <aarcange@redhat.com>
In order to allow early shipping transparent hugepage feature enabled
only inside MADV_HUGEPAGE and not globally to diminish the risk of
unexpected performance regressions on non-hypervisor related usages
I'd need this little define registered. This is also to avoid things
like this:
#define MADV_DOFORK 11 /* do inherit across fork */
#define MADV_HWPOISON 100 /* poison a page for testing */
Picking random number not so nice... and with my proof of concept
patch posted working and boosting performance equally to hugetlbfs but
without its limitations, I think it is a given that eventually KVM
will run inside MADV_HUGEPAGE madvise regions only, so I see a
negligeable risk to pollute the kernel in including this as first bit
of the full patchset.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---
The rest of the transparent hugepage patchset is very ready for
inclusion too with all cleanups requested and after full handling of
all review on linux-mm so far, with the only exception of khugepaged
that is about to be finished, expect a new submit on linux-mm in a few
days. Then we'll have to plug Mel memory compaction on top of it.
(in addition to the below, /sys/kernel/mm/transparent_hugepage also
has been moved to some other distro specific location to avoid any
possible risk of clashes or confusion with future mainline behavior)
Thanks,
Andrea
diff --git a/include/asm-generic/mman-common.h b/include/asm-generic/mman-common.h
--- a/include/asm-generic/mman-common.h
+++ b/include/asm-generic/mman-common.h
@@ -45,6 +45,8 @@
#define MADV_MERGEABLE 12 /* KSM may merge identical pages */
#define MADV_UNMERGEABLE 13 /* KSM may not merge identical pages */
+#define MADV_HUGEPAGE 14 /* Worth backing with hugepages */
+
/* compatibility flags */
#define MAP_FILE 0
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] register MADV_HUGEPAGE
2010-01-16 18:46 [PATCH] register MADV_HUGEPAGE Andrea Arcangeli
@ 2010-01-17 11:08 ` Christoph Hellwig
0 siblings, 0 replies; 2+ messages in thread
From: Christoph Hellwig @ 2010-01-17 11:08 UTC (permalink / raw)
To: Andrea Arcangeli; +Cc: Andrew Morton, linux-kernel, linux-mm, davem
On Sat, Jan 16, 2010 at 07:46:42PM +0100, Andrea Arcangeli wrote:
> From: Andrea Arcangeli <aarcange@redhat.com>
>
> In order to allow early shipping transparent hugepage feature enabled
> only inside MADV_HUGEPAGE and not globally to diminish the risk of
> unexpected performance regressions on non-hypervisor related usages
> I'd need this little define registered. This is also to avoid things
> like this:
NACK, usespace ABIs only go in when features are added. There's a more
than large enough chance that it will change for one reason or another.
And while transparent hugepages are a good feature to add, it's still in
a far to early stage to go on with it.
^ permalink raw reply [flat|nested] 2+ messages in thread
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