[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] an issue with 'xm save'
On Wed, Sep 26, 2012 at 04:48:42PM +0800, Zhenzhong Duan wrote: > Konrad Rzeszutek Wilk wrote: > >On Fri, Sep 21, 2012 at 05:41:27PM +0800, Zhenzhong Duan wrote: > >>Hi maintainers, > >> > >>I found there is an issue when 'xm save' a pvm guest. See below: > >> > >>When I do save then restore once, CPU(%) in xentop showed around 99%. > >>When I do that second time, CPU(%) showed 199% > >> > >>top in dom0 showed: > >> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND > >> 20946 root 18 -2 10984 1284 964 S 19.8 0.3 0:48.93 block > >> 4939 root 18 -2 10984 1288 964 S 19.5 0.3 1:34.68 block > >> > >>I could kill the block process, then all look normal again. > > > >What is the 'block' process? If you attach 'perf' to it do you get an idea > >of what it is spinning at? > It's /etc/xen/scripts/block > I add 'set -x' to /etc/xen/scripts/block, found it blocked at claim_lock. > When domU was created first time, claim_lock/release_lock finished quickly, > when 'xm save' was called, claim_lock spin in its own while loop. > I can ensure no other domU create/save/etc happen when I test. OK, so how come you have two block processes? Is it b/c you have two disks attached to the guest? The are multiple claim_lock in the shell script - do you know where each of two threads are spinning? Are they spinning on the same function? > >>xen and xen-tools are both generated with xen-unstable. > >>I tried xl, but it segfault. > > > >It segfaulted? When doing 'xl save' or 'xl resume'? Or just allocating > >the guest? > When xl create vm.cfg > >>I also tried ovm3.1.1(xen-4.1.2-18.el5.1 and xen-tools-4.1.2-18.el5.1), > >>can't reproduce. > > > >So the issue is only present with Xen-unstable? > Yes, I found in /etc/xen/scripts/locking.sh of ovm3.1.1, func > claim_lock is quite different to xen-unstable Could that be upstreamed? Perhaps that was fix that was added for this exact reason and it just never got upstreamed? > Maybe this is why ovm3.1.1 work with save/restore. > >Did you clear _any_ older Xen libraries/tools when you installed > >Xen-unstable? > No, I built xen and xen-tools on el5, then installed to ovm3.1.1 on > other partition. Excellent. > thanks > zduan > _______________________________________________ > Xen-devel mailing list > Xen-devel@xxxxxxxxxxxxx > http://lists.xen.org/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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