* Wen Congyang (wency@xxxxxxxxxxxxxx) wrote: > On 05/29/2015 12:24 AM, Dr. David Alan Gilbert wrote: > > * zhanghailiang (zhang.zhanghailiang@xxxxxxxxxx) 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? I've seen two ways: 1) Shutdown the guest - when the guest exits and qemu exits, then I see this problem 2) If there is a problem with the colo-proxy-script (I got the path wrong) so qemu quit. > > [<ffffffff810d8c0c>] wait_rcu_gp+0x5c/0x80 > > [<ffffffff810ddb05>] synchronize_rcu+0x45/0xd0 > > [<ffffffffa0a251e5>] colo_node_release+0x35/0x50 [nfnetlink_colo] > > [<ffffffffa0a25795>] colonl_close_event+0xe5/0x160 [nfnetlink_colo] > > [<ffffffff81090c96>] notifier_call_chain+0x66/0x90 > > [<ffffffff8109154c>] atomic_notifier_call_chain+0x6c/0x110 > > [<ffffffff815eee07>] netlink_release+0x5b7/0x7f0 > > [<ffffffff815878bf>] sock_release+0x1f/0x90 > > [<ffffffff81587942>] sock_close+0x12/0x20 > > [<ffffffff812193c3>] __fput+0xd3/0x210 > > [<ffffffff8121954e>] ____fput+0xe/0x10 > > [<ffffffff8108d9f7>] task_work_run+0xb7/0xf0 > > [<ffffffff81002d4d>] do_notify_resume+0x8d/0xa0 > > [<ffffffff81722b66>] int_signal+0x12/0x17 > > [<ffffffffffffffff>] 0xffffffffffffffff > > Thanks for your test. The backtrace is very useful, and we will fix it soon. Thank you, Dave > > > > 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 > > > >> > -- Dr. David Alan Gilbert / dgilbert@xxxxxxxxxx / Manchester, UK -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
