[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH COLO-Frame v5 00/29] COarse-grain LOck-stepping(
Dr. David Alan Gilbert
Re: [Qemu-devel] [PATCH COLO-Frame v5 00/29] COarse-grain LOck-stepping(COLO) Virtual Machines for Non-stop Service
Fri, 29 May 2015 09:01:05 +0100
* Wen Congyang (address@hidden) wrote:
> On 05/29/2015 12:24 AM, Dr. David Alan Gilbert wrote:
> > * zhanghailiang (address@hidden) 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
> > (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
2) If there is a problem with the colo-proxy-script (I got the path wrong)
> > [<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.
> > 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.
> Wen Congyang
> > Thanks,
> > Dave
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- [Qemu-devel] [PATCH COLO-Frame v5 26/29] COLO NIC: Implement NIC checkpoint and failover, (continued)
- [Qemu-devel] [PATCH COLO-Frame v5 26/29] COLO NIC: Implement NIC checkpoint and failover, zhanghailiang, 2015/05/21
- [Qemu-devel] [PATCH COLO-Frame v5 16/29] COLO failover: Don't do failover during loading VM's state, zhanghailiang, 2015/05/21
- [Qemu-devel] [PATCH COLO-Frame v5 04/29] migration: Integrate COLO checkpoint process into migration, zhanghailiang, 2015/05/21
- [Qemu-devel] [PATCH COLO-Frame v5 07/29] COLO: Add a new RunState RUN_STATE_COLO, zhanghailiang, 2015/05/21
- [Qemu-devel] [PATCH COLO-Frame v5 22/29] COLO: Handle nfnetlink message from proxy module, zhanghailiang, 2015/05/21
- [Qemu-devel] [PATCH COLO-Frame v5 17/29] COLO: Add new command parameter 'colo_nicname' 'colo_script' for net, zhanghailiang, 2015/05/21
- Re: [Qemu-devel] [PATCH COLO-Frame v5 00/29] COarse-grain LOck-stepping(COLO) Virtual Machines for Non-stop Service, Dr. David Alan Gilbert, 2015/05/21
- Re: [Qemu-devel] [PATCH COLO-Frame v5 00/29] COarse-grain LOck-stepping(COLO) Virtual Machines for Non-stop Service, Dr. David Alan Gilbert, 2015/05/28