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

["Chenjia (C)" <chenjia09@xxxxxxxxxx>]

when we use the Xen4.8.7(we compile from the source and install on SUSE 12 ), 
if we create the VM, we got the error information:

libxl: error: libxl_exec.c:118:libxl_report_child_exitstatus: 
/etc/xen/scripts/vif-bridge online [8284] exited with error status 127
libxl: error: libxl_create.c:1461:domcreate_attach_devices: unable to add nic 
devices


our config file is(we called "xl create -c cfg" to create the vm) :
arch = 'x86_64'
#name = "sample_evn_win7_x64"
name = "aap_40"
memory = 1024
vcpus = 1
builder='hvm'
boot = "cd"
vif = [ "mac=18:C5:8A:15:C1:39,bridge=virbr0" ]
hap = 1
acpi = 1
altp2mhvm = 1
shadow_memory = 16
disk = [ 'tap:qcow2:/home/huawei/vm/win7_x64/win7_work40.qcow2,xvda,w' ]
vnc = 1
vnclisten="0.0.0.0"
usb=1
usbdevice = "tablet"

could you plz help us why this error happen? How to resolve it ? thank you, 
wish your reply.

-----邮件原件-----
发件人: Wei Liu [mailto:wei.liu2@xxxxxxxxxx] 
发送时间: 2017年11月13日 17:51
收件人: Chenjia (C) <chenjia09@xxxxxxxxxx>
抄送: wei.liu2@xxxxxxxxxx; HUANG SHENGQIANG <huang.shengqiang@xxxxxxxxxx>; 
Yaoshaomin <yaoshaomin@xxxxxxxxxx>; xen-devel@xxxxxxxxxxxxxxxxxxxx
主题: Re: 答复: Re: [Xen-devel] Help：Can xen restore several snapshots more faster 
at same time？

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:+1-60461804
> 23>(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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