From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from g4t0014.houston.hp.com ([15.201.24.17]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1UEyd5-0002v0-9n for kexec@lists.infradead.org; Mon, 11 Mar 2013 09:02:48 +0000 Message-ID: <513D9DB1.7040100@hp.com> Date: Mon, 11 Mar 2013 17:02:41 +0800 From: Jingbai Ma MIME-Version: 1.0 Subject: Re: [RFC PATCH 0/5] crash dump bitmap: scan memory pages in kernel to speedup kernel dump process References: <20130307145808.29098.41592.stgit@k.asiapacific.hpqcorp.net> <20130307152108.GC2790@redhat.com> <5139B827.3050500@hp.com> <20130309.133118.214580151.d.hatayama@jp.fujitsu.com> In-Reply-To: <20130309.133118.214580151.d.hatayama@jp.fujitsu.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: HATAYAMA Daisuke Cc: kexec@lists.infradead.org, linux-kernel@vger.kernel.org, lisa.mitchell@hp.com, mingo@redhat.com, kumagai-atsushi@mxc.nes.nec.co.jp, jingbai.ma@hp.com, hpa@zytor.com, yinghai@kernel.org, vgoyal@redhat.com, ebiederm@xmission.com On 03/09/2013 12:31 PM, HATAYAMA Daisuke wrote: > From: Jingbai Ma > Subject: Re: [RFC PATCH 0/5] crash dump bitmap: scan memory pages in kernel to speedup kernel dump process > Date: Fri, 8 Mar 2013 18:06:31 +0800 > >> On 03/07/2013 11:21 PM, Vivek Goyal wrote: >>> On Thu, Mar 07, 2013 at 10:58:18PM +0800, Jingbai Ma wrote: > ... >>> First of all 64MB per TB should not be a huge deal. And makedumpfile >>> also has this cyclic mode where you process a map, discard it and then >>> move on to next section. So memory usage remains constant at the >>> expense >>> of processing time. >> >> Yes, that's true. But in cyclic mode, makedumpfile will have to >> write/read bitmap from storage, it will also impact the performance. >> I have measured the penalty for cyclic mode is about 70% >> slowdown. Maybe could be faster after mmap implemented. > > I guess the slowdown came from the issue that enough VMCOREINFO was > not provided from the kernel, and unnecessary filtering processing for > free pages is done multiple times. Thanks for your comments! It would be very helpful. I will test it on the machine again. -- Jingbai Ma (jingbai.ma@hp.com) _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec