From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: Slow vmalloc in 2.6.35-rc3 Date: Sun, 27 Jun 2010 12:17:42 +0300 Message-ID: <4C271736.5010102@redhat.com> References: <4C232324.7070305@redhat.com> <20100624151427.GH10441@laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-kernel , KVM list , Andrew Morton To: Nick Piggin Return-path: In-Reply-To: <20100624151427.GH10441@laptop> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 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