Re: [Xen-devel] 答复: Re: Help：Can xen restore several snapshots more faster at same time？

[Wei Liu <wei.liu2@xxxxxxxxxx>]

Please avoid top-posting.

On Mon, Nov 13, 2017 at 08:25:16AM +0000, Chenjia (C) wrote:
> 1.       is there some way to improve the xenstored process performance?
> 

The latest version of Cxenstored and Oxenstored have improved
transaction handling. Not sure which version you're using.

> 2.       We also try the virsh tool to restore several xen at same
> time ,we fount the virsh can restore 40+ snapshot(1G per snapshot) at
> same time, the performance is good when snapshot is all in ramdisk.
> But we can’t let all the snapshot is always in ramdisk for it is too
> big. Is there some way to reduce these virsh snapshots space?(these
> snapshot is same: same OS, same config, but need with different IP
> address)

For libvirt question you need to ask on libvirt list.

> 
> Would you please offer us some feedback? Thanks.
> By the way, can we talk with Chinese if possible?

Sorry but communication on mailing list needs to be in English so other
people can join the discussion and / or provide suggestions.

> 
> 发件人: HUANG SHENGQIANG
> 发送时间: 2017年11月6日 18:32
> 收件人: Chenjia (C) <chenjia09@xxxxxxxxxx<mailto:chenjia09@xxxxxxxxxx>>
> 主题: FW: Re: [Xen-devel] Help：Can xen restore several snapshots more faster at 
> same time？
> 
> --------------------------------------------------
> HUANG SHENGQIANG HUANG SHENGQIANG
> M: 
> +86-18201587800<tel:+86-18201587800>(优先)/+1-6046180423<tel:+1-6046180423>(海外出差)
> E: huang.shengqiang@xxxxxxxxxx<mailto:huang.shengqiang@xxxxxxxxxx>
> 产品与解决方案-交换机与企业网关解决方案架构与设计部
> Products & Solutions-Switch & Enterprise Gateway Solution Architecture & 
> Design Dept
> From:Wei Liu
> To:HUANG SHENGQIANG,
> Cc:xen-devel@xxxxxxxxxxxxxxxxxxxx,Wangjianbing,Wei Liu,
> Date:2017-11-06 18:28:58
> Subject:Re: [Xen-devel] Help：Can xen restore several snapshots more faster at 
> same time？
> 
> On Mon, Nov 06, 2017 at 04:38:51AM +0000, HUANG SHENGQIANG wrote:
> > Dear XEN expert,
> >
> > I find a blocker issue in my project. Would you please offer us some 
> > feedback?
> >
> > The description from my development team:
> > we need restore as much as xen snapshot at same times, but we found ‘xl 
> > restore’ command is work linearly,  if we want to restore a new xen 
> > snapshot, we need to wait for the previous snapshot finish it’s work. We 
> > try to debug the xl source ,we found the follow information:
> > [cid:image001.png@01D356F6.B8EE87E0]
> >
> 
> Please don't send pictures.
> 
> > When an snapshot is being restore, we can see another process is blocked.  
> > We trying to delete the acquire_lock from the source code , then we see all 
> > the snapshots are being restore at same time, but restore is still very 
> > slow, one snapshot needs about 25 seconds  to finish restore(our 
> > environment is cpu E52620,  256G memory, SSD hard disk. The snapshot is 
> > Win7 OS with 2G memory).
> >
> 
> There is a lock in xl as you can see in the stack trace.
> 
> > So , does xen have the way to restore more faster when several snapshot is 
> > restore at same time? Why KVM can restore several snapshot fast at same 
> > time? (We try the same experiment in KVM, we got we can restore about 50+ 
> > snapshot in 20S. )
> >
> 
> Part of the toolstack needs to be reworked. You can start by removing
> the lock in xl to see what breaks.

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