From: Avi Kivity <avi@redhat.com>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH QEMU] transparent hugepage support
Date: Sat, 13 Mar 2010 10:28:32 +0200 [thread overview]
Message-ID: <4B9B4CB0.7080200@redhat.com> (raw)
In-Reply-To: <20100311160505.GG5677@random.random>
On 03/11/2010 06:05 PM, Andrea Arcangeli wrote:
> On Thu, Mar 11, 2010 at 05:52:16PM +0200, Avi Kivity wrote:
>
>> That is a little wasteful. How about a hint to mmap() requesting proper
>> alignment (MAP_HPAGE_ALIGN)?
>>
> So you suggest adding a new kernel feature to mmap? Not sure if it's
> worth it, considering it'd also increase the number of vmas because it
> will have to leave an hole. Wasting 2M-4k of virtual memory is likely
> cheaper than having 1 more vma in the rbtree for every page fault. So
> I think it's better to just malloc and adjust ourselfs on the next
> offset which is done in userland by qemu_memalign I think.
>
>
Won't we get a new vma anyway due to the madvise() call later?
But I agree it isn't worth it.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
next prev parent reply other threads:[~2010-03-13 8:28 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-11 15:14 [Qemu-devel] [PATCH QEMU] transparent hugepage support Andrea Arcangeli
2010-03-11 15:52 ` Avi Kivity
2010-03-11 16:05 ` Andrea Arcangeli
2010-03-13 8:28 ` Avi Kivity [this message]
2010-03-13 17:47 ` Andrea Arcangeli
2010-03-11 16:28 ` Paul Brook
2010-03-11 16:46 ` Andrea Arcangeli
2010-03-11 17:55 ` Paul Brook
2010-03-11 18:49 ` Andrea Arcangeli
2010-03-12 11:36 ` Paul Brook
2010-03-12 14:52 ` Andrea Arcangeli
2010-03-12 16:04 ` Paul Brook
2010-03-12 16:17 ` Andrea Arcangeli
2010-03-12 16:24 ` Paul Brook
2010-03-12 16:57 ` Andrea Arcangeli
2010-03-12 17:10 ` Paul Brook
2010-03-12 17:41 ` Andrea Arcangeli
2010-03-12 18:17 ` Paul Brook
2010-03-12 18:36 ` Andrea Arcangeli
2010-03-12 18:41 ` Paul Brook
2010-03-12 18:51 ` Andrea Arcangeli
2010-03-12 22:40 ` Jamie Lokier
2010-03-12 16:10 ` Paul Brook
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