[Xen-bugs] [Bug 545] New: xm vcpu-list causes xenstored to utilize 99% cpu...

[bugzilla-daemon@xxxxxxxxxxxxxxxxxxx]

http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=545

           Summary: xm vcpu-list causes xenstored to utilize 99% cpu...
           Product: Xen
           Version: 3.0-testing
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: major
          Priority: P1
         Component: Tools
        AssignedTo: xen-bugs@xxxxxxxxxxxxxxxxxxx
        ReportedBy: Shaun.Reitan@xxxxxxxxxxx


I have 40 DomU's running but idle and found that xm list takes about 3 seconds 
to run and display output, i then found that xm vcpu-list took about 15 seconds 
to run and while it was running it was causing xenstored to utilize 99% cpu the 
whole time.  A strace attached to xenstored looked like a full dump of the db 
was happening for each guest but i can be sure of that.  Even worse, when i had 
dom0 using 4 cpu's (hyperthreads) xm vcpu-list took well over 4 minutes to run 
a few times!!!  A mailing list post i posted about this may be useful to read 
http://lists.xensource.com/archives/html/xen-users/2006-02/msg00835.html i 
though it was xend that was lagging in that post but really it's xenstored that 
appears to be causing the wait.

Talked to rharper on irc and his comments where teh following...

[14:07] <rharper> aliguori: vcpu-list should require anything from the store
[14:07] <rharper> the only thing in the store vcpu related is the availability 
value which only changes via vcpu-set and on domain creation

I dont know enough about python or even xen but my guess is that the problem is 
in main.py in the def format_cpumap since it's calling 'from 
xen.xend.XendClient import server' which i imagine is making the call to 
xenstore?  just a guess, i could be out in left field...

If whoever is looking at this want to get a hold of me, other than here you can 
probably find me on the #xen irc channel on irc.oftc.net (nick is usually shaun 
or shaun2222)

thanks.

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