From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from cantor.suse.de ([195.135.220.2] helo=mx1.suse.de) by canuck.infradead.org with esmtps (Exim 4.72 #1 (Red Hat Linux)) id 1PKajM-0003gB-6O for kexec@lists.infradead.org; Mon, 22 Nov 2010 18:03:08 +0000 Date: Mon, 22 Nov 2010 09:59:09 -0800 From: Greg KH Subject: Re: [Stable-review] [08/45] mm, x86: Saving vmcore with non-lazy freeing of vmas Message-ID: <20101122175909.GB18867@suse.de> References: <20101119214410.087440440@clark.site> <1290219372.3818.113.camel@localhost> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1290219372.3818.113.camel@localhost> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Ben Hutchings Cc: akpm@linux-foundation.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, stable@kernel.org, stable-review@kernel.org, Ingo Molnar , torvalds@linux-foundation.org, Cliff Wickman , alan@lxorguk.ukuu.org.uk On Sat, Nov 20, 2010 at 02:16:12AM +0000, Ben Hutchings wrote: > On Fri, 2010-11-19 at 13:42 -0800, Greg KH wrote: > > 2.6.32-stable review patch. If anyone has any objections, please let us know. > > > > ------------------ > > > > From: Cliff Wickman > > > > commit 3ee48b6af49cf534ca2f481ecc484b156a41451d upstream. > > > > During the reading of /proc/vmcore the kernel is doing > > ioremap()/iounmap() repeatedly. And the buildup of un-flushed > > vm_area_struct's is causing a great deal of overhead. (rb_next() > > is chewing up most of that time). > > > > This solution is to provide function set_iounmap_nonlazy(). It > > causes a subsequent call to iounmap() to immediately purge the > > vma area (with try_purge_vmap_area_lazy()). > > > > With this patch we have seen the time for writing a 250MB > > compressed dump drop from 71 seconds to 44 seconds. > [...] > > Useful, but it doesn't seem to meet the criteria for stable updates. I disagree, it's a major speedup, and an obvious bugfix for the problem. thanks, greg k-h _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec