From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wen Congyang Subject: Re: [PATCH COLO-Frame v5 00/29] COarse-grain LOck-stepping(COLO) Virtual Machines for Non-stop Service Date: Fri, 29 May 2015 09:29:40 +0800 Message-ID: <5567C104.3070805@cn.fujitsu.com> References: <1432196001-10352-1-git-send-email-zhang.zhanghailiang@huawei.com> <20150528162402.GE2127@work-vm> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Cc: , , , , , , , , , , , To: "Dr. David Alan Gilbert" , zhanghailiang Return-path: Received: from cn.fujitsu.com ([59.151.112.132]:27204 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753168AbbE2BZZ (ORCPT ); Thu, 28 May 2015 21:25:25 -0400 In-Reply-To: <20150528162402.GE2127@work-vm> Sender: netfilter-devel-owner@vger.kernel.org List-ID: On 05/29/2015 12:24 AM, Dr. David Alan Gilbert wrote: > * zhanghailiang (zhang.zhanghailiang@huawei.com) wrote: >> This is the 5th version of COLO, here is only COLO frame part, include: VM checkpoint, >> failover, proxy API, block replication API, not include block replication. >> The block part has been sent by wencongyang: >> "[Qemu-devel] [PATCH COLO-Block v5 00/15] Block replication for continuous checkpoints" >> >> we have finished some new features and optimization on COLO (As a development branch in github), >> but for easy of review, it is better to keep it simple now, so we will not add too much new >> codes into this frame patch set before it been totally reviewed. >> >> You can get the latest integrated qemu colo patches from github (Include Block part): >> https://github.com/coloft/qemu/commits/colo-v1.2-basic >> https://github.com/coloft/qemu/commits/colo-v1.2-developing (more features) >> >> Please NOTE the difference between these two branch. >> colo-v1.2-basic is exactly same with this patch series, which has basic features of COLO. >> Compared with colo-v1.2-basic, colo-v1.2-developing has some optimization in the >> process of checkpoint, including: >> 1) separate ram and device save/load process to reduce size of extra memory >> used during checkpoint >> 2) live migrate part of dirty pages to slave during sleep time. >> Besides, we add some statistic info in colo-v1.2-developing, which you can get these stat >> info by using command 'info migrate'. > > > Hi, > I have that running now. > > Some notes: > 1) The colo-proxy is working OK until qemu quits, and then it gets an RCU problem; see below > 2) I've attached some minor tweaks that were needed to build with the 4.1rc kernel I'm using; > they're very minor changes and I don't think related to (1). > 3) I've also included some minor fixups I needed to get the -developing world > to build; my compiler is fussy about unused variables etc - but I think the code > in ram_save_complete in your -developing patch is wrong because there are two > 'pages' variables and the one in the inner loop is the only one changed. > 4) I've started trying simple benchmarks and tests now: > a) With a simple web server most requests have very little overhead, the comparison > matches most of the time; I do get quite large spikes (0.04s->1.05s) which I guess > corresponds to when a checkpoint happens, but I'm not sure why the spike is so big, > since the downtime isn't that big. > b) I tried something with more dynamic pages - the front page of a simple bugzilla > install; it failed the comparison every time; it took me a while to figure out > why, but it generates a unique token in it's javascript each time (for a password reset > link), and I guess the randomness used by that doesn't match on the two hosts. > It surprised me, because I didn't expect this page to have much randomness > in. > > 4a is really nice - it shows the benefit of COLO over the simple checkpointing; > checkpoints happen very rarely. > > The colo-proxy rcu problem I hit shows as rcu-stalls in both primary and secondary > after the qemu quits; the backtrace of the qemu stack is: How to reproduce it? Use monitor command quit to quit qemu? Or kill the qemu? > > [] wait_rcu_gp+0x5c/0x80 > [] synchronize_rcu+0x45/0xd0 > [] colo_node_release+0x35/0x50 [nfnetlink_colo] > [] colonl_close_event+0xe5/0x160 [nfnetlink_colo] > [] notifier_call_chain+0x66/0x90 > [] atomic_notifier_call_chain+0x6c/0x110 > [] netlink_release+0x5b7/0x7f0 > [] sock_release+0x1f/0x90 > [] sock_close+0x12/0x20 > [] __fput+0xd3/0x210 > [] ____fput+0xe/0x10 > [] task_work_run+0xb7/0xf0 > [] do_notify_resume+0x8d/0xa0 > [] int_signal+0x12/0x17 > [] 0xffffffffffffffff Thanks for your test. The backtrace is very useful, and we will fix it soon. > > that's with both the 423a8e268acbe3e644a16c15bc79603cfe9eb084 from yesterday and > older e58e5152b74945871b00a88164901c0d46e6365e tags on colo-proxy. > I'm not sure of the right fix; perhaps it might be possible to replace the > synchronize_rcu in colo_node_release by a call_rcu that does the kfree later? I agree with it. Thanks Wen Congyang > > Thanks, > > Dave > >> From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52087) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yy93G-0002Wo-Ic for qemu-devel@nongnu.org; Thu, 28 May 2015 21:25:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Yy93D-0007Gf-AS for qemu-devel@nongnu.org; Thu, 28 May 2015 21:25:34 -0400 Received: from [59.151.112.132] (port=29987 helo=heian.cn.fujitsu.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yy93C-0007GR-2V for qemu-devel@nongnu.org; Thu, 28 May 2015 21:25:31 -0400 Message-ID: <5567C104.3070805@cn.fujitsu.com> Date: Fri, 29 May 2015 09:29:40 +0800 From: Wen Congyang MIME-Version: 1.0 References: <1432196001-10352-1-git-send-email-zhang.zhanghailiang@huawei.com> <20150528162402.GE2127@work-vm> In-Reply-To: <20150528162402.GE2127@work-vm> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH COLO-Frame v5 00/29] COarse-grain LOck-stepping(COLO) Virtual Machines for Non-stop Service List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" , zhanghailiang Cc: lizhijian@cn.fujitsu.com, quintela@redhat.com, yunhong.jiang@intel.com, eddie.dong@intel.com, peter.huangpeng@huawei.com, qemu-devel@nongnu.org, arei.gonglei@huawei.com, netfilter-devel@vger.kernel.org, amit.shah@redhat.com, david@gibson.dropbear.id.au On 05/29/2015 12:24 AM, Dr. David Alan Gilbert wrote: > * zhanghailiang (zhang.zhanghailiang@huawei.com) wrote: >> This is the 5th version of COLO, here is only COLO frame part, include: VM checkpoint, >> failover, proxy API, block replication API, not include block replication. >> The block part has been sent by wencongyang: >> "[Qemu-devel] [PATCH COLO-Block v5 00/15] Block replication for continuous checkpoints" >> >> we have finished some new features and optimization on COLO (As a development branch in github), >> but for easy of review, it is better to keep it simple now, so we will not add too much new >> codes into this frame patch set before it been totally reviewed. >> >> You can get the latest integrated qemu colo patches from github (Include Block part): >> https://github.com/coloft/qemu/commits/colo-v1.2-basic >> https://github.com/coloft/qemu/commits/colo-v1.2-developing (more features) >> >> Please NOTE the difference between these two branch. >> colo-v1.2-basic is exactly same with this patch series, which has basic features of COLO. >> Compared with colo-v1.2-basic, colo-v1.2-developing has some optimization in the >> process of checkpoint, including: >> 1) separate ram and device save/load process to reduce size of extra memory >> used during checkpoint >> 2) live migrate part of dirty pages to slave during sleep time. >> Besides, we add some statistic info in colo-v1.2-developing, which you can get these stat >> info by using command 'info migrate'. > > > Hi, > I have that running now. > > Some notes: > 1) The colo-proxy is working OK until qemu quits, and then it gets an RCU problem; see below > 2) I've attached some minor tweaks that were needed to build with the 4.1rc kernel I'm using; > they're very minor changes and I don't think related to (1). > 3) I've also included some minor fixups I needed to get the -developing world > to build; my compiler is fussy about unused variables etc - but I think the code > in ram_save_complete in your -developing patch is wrong because there are two > 'pages' variables and the one in the inner loop is the only one changed. > 4) I've started trying simple benchmarks and tests now: > a) With a simple web server most requests have very little overhead, the comparison > matches most of the time; I do get quite large spikes (0.04s->1.05s) which I guess > corresponds to when a checkpoint happens, but I'm not sure why the spike is so big, > since the downtime isn't that big. > b) I tried something with more dynamic pages - the front page of a simple bugzilla > install; it failed the comparison every time; it took me a while to figure out > why, but it generates a unique token in it's javascript each time (for a password reset > link), and I guess the randomness used by that doesn't match on the two hosts. > It surprised me, because I didn't expect this page to have much randomness > in. > > 4a is really nice - it shows the benefit of COLO over the simple checkpointing; > checkpoints happen very rarely. > > The colo-proxy rcu problem I hit shows as rcu-stalls in both primary and secondary > after the qemu quits; the backtrace of the qemu stack is: How to reproduce it? Use monitor command quit to quit qemu? Or kill the qemu? > > [] wait_rcu_gp+0x5c/0x80 > [] synchronize_rcu+0x45/0xd0 > [] colo_node_release+0x35/0x50 [nfnetlink_colo] > [] colonl_close_event+0xe5/0x160 [nfnetlink_colo] > [] notifier_call_chain+0x66/0x90 > [] atomic_notifier_call_chain+0x6c/0x110 > [] netlink_release+0x5b7/0x7f0 > [] sock_release+0x1f/0x90 > [] sock_close+0x12/0x20 > [] __fput+0xd3/0x210 > [] ____fput+0xe/0x10 > [] task_work_run+0xb7/0xf0 > [] do_notify_resume+0x8d/0xa0 > [] int_signal+0x12/0x17 > [] 0xffffffffffffffff Thanks for your test. The backtrace is very useful, and we will fix it soon. > > that's with both the 423a8e268acbe3e644a16c15bc79603cfe9eb084 from yesterday and > older e58e5152b74945871b00a88164901c0d46e6365e tags on colo-proxy. > I'm not sure of the right fix; perhaps it might be possible to replace the > synchronize_rcu in colo_node_release by a call_rcu that does the kfree later? I agree with it. Thanks Wen Congyang > > Thanks, > > Dave > >>