From: Avi Kivity <avi@redhat.com>
To: Nick Piggin <npiggin@suse.de>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
KVM list <kvm@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: Slow vmalloc in 2.6.35-rc3
Date: Sun, 27 Jun 2010 12:17:42 +0300 [thread overview]
Message-ID: <4C271736.5010102@redhat.com> (raw)
In-Reply-To: <20100624151427.GH10441@laptop>
On 06/24/2010 06:14 PM, Nick Piggin wrote:
> On Thu, Jun 24, 2010 at 12:19:32PM +0300, Avi Kivity wrote:
>
>> I see really slow vmalloc performance on 2.6.35-rc3:
>>
> Can you try this patch?
> http://userweb.kernel.org/~akpm/mmotm/broken-out/mm-vmap-area-cache.patch
>
The patch completely eliminates the problem.
>>
>> It seems completely wrong - iterating 8 levels of a binary tree
>> shouldn't take half a millisecond.
>>
> It's not iterating down the tree, it's iterating through the
> nodes to find a free area. Slows down because lazy vunmap means
> that quite a lot of little areas build up right at the start of
> our search start address. The vmap cache should hopefully fix
> it up.
>
I see, thanks.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2010-06-27 9:17 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-24 9:19 Slow vmalloc in 2.6.35-rc3 Avi Kivity
2010-06-24 15:14 ` Nick Piggin
2010-06-27 9:17 ` Avi Kivity [this message]
2010-06-28 3:30 ` Nick Piggin
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