From: John McCorquodale <mcq@rockgeek.org>
To: linux-kernel@vger.kernel.org
Subject: Transparent Hugepage Nit
Date: Tue, 15 Jan 2013 13:50:41 -0700 [thread overview]
Message-ID: <20130115205041.GA12113@rockgeek.org> (raw)
Suppose a hugepage-aligned mmap(MAP_ANONYMOUS) mapping has been madvise()d
HUGEPAGE. If a subeqeuent call to mremap() grows the mapping and has to
move the mapping, the hugepage-alignment is not preserved in the choice of
new address (in 3.7.2).
I can workaround this by doing a 1-hugepage-oversized remap to find a new
aligned address and then size it back down MREMAP_FIXED, but that's probably
a lot of frags to 4k pages and back that aren't necessary.
Should it not be the case that mremap(MAYMOVE) on something advised hugepage
ALWAYS chooses a hugepage-aligned address? This would be handy when doing the
initial allocation too: mmap, madvise, mremap (to the same size) to get
alignment.
Cheers,
-mcq
next reply other threads:[~2013-01-15 20:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-15 20:50 John McCorquodale [this message]
2013-01-15 21:26 ` Transparent Hugepage Nit Andi Kleen
2013-01-16 15:50 ` Rob Landley
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