RE: [Xen-devel] Dom0 Hang for large VCPU counts > PCPU

["Woller, Thomas" <thomas.woller@xxxxxxx>]

Not sure if this is useful.  We have a box with 8 cores, and can run 32
VCPUs without issue on AMD-V with suse10 64b smp guest.
This data though is from around january 8th, so it's a bit stale.  I
don't have the exact c/s that the tests were run on, or the guest config
parms, but I think it was with 6Gig of RAM for the guest. :P  I can try
this guest again next day or 2 if useful.
tom

 XEND_DEBUG = 1
Name                              ID  VCPU   CPU State   Time(s) CPU
Affinity
Domain-0                           0     0     0   -b-     172.5 any cpu
Domain-0                           0     1     1   -b-      60.0 any cpu
Domain-0                           0     2     3   -b-      25.2 any cpu
Domain-0                           0     3     3   r--      10.2 any cpu
Domain-0                           0     4     2   -b-       8.7 any cpu
Domain-0                           0     5     5   -b-       6.8 any cpu
Domain-0                           0     6     6   -b-       3.6 any cpu
Domain-0                           0     7     0   -b-       4.8 any cpu
suse10_x64_smp                     4     0     6   -b-     144.2 any cpu
suse10_x64_smp                     4     1     4   -b-      36.3 any cpu
suse10_x64_smp                     4     2     4   -b-      26.5 any cpu
suse10_x64_smp                     4     3     3   ---     883.8 any cpu
suse10_x64_smp                     4     4     5   r--     885.6 any cpu
suse10_x64_smp                     4     5     6   ---     883.6 any cpu
suse10_x64_smp                     4     6     7   ---     884.2 any cpu
suse10_x64_smp                     4     7     2   ---     884.4 any cpu
suse10_x64_smp                     4     8     4   ---     886.8 any cpu
suse10_x64_smp                     4     9     7   r--     885.6 any cpu
suse10_x64_smp                     4    10     6   ---     885.2 any cpu
suse10_x64_smp                     4    11     4   r--     884.0 any cpu
suse10_x64_smp                     4    12     0   r--     884.6 any cpu
suse10_x64_smp                     4    13     3   ---     883.7 any cpu
suse10_x64_smp                     4    14     1   ---     887.0 any cpu
suse10_x64_smp                     4    15     1   ---     884.7 any cpu
suse10_x64_smp                     4    16     0   ---     885.5 any cpu
suse10_x64_smp                     4    17     7   ---     884.2 any cpu
suse10_x64_smp                     4    18     2   r--     885.9 any cpu
suse10_x64_smp                     4    19     1   ---     886.0 any cpu
suse10_x64_smp                     4    20     6   ---     885.7 any cpu
suse10_x64_smp                     4    21     6   ---     886.4 any cpu
suse10_x64_smp                     4    22     2   ---     885.6 any cpu
suse10_x64_smp                     4    23     5   ---     888.9 any cpu
suse10_x64_smp                     4    24     4   ---     885.0 any cpu
suse10_x64_smp                     4    25     0   ---     885.2 any cpu
suse10_x64_smp                     4    26     4   ---     885.0 any cpu
suse10_x64_smp                     4    27     7   ---     885.1 any cpu
suse10_x64_smp                     4    28     4   ---     882.4 any cpu
suse10_x64_smp                     4    29     6   ---     884.1 any cpu
suse10_x64_smp                     4    30     5   ---     883.6 any cpu
suse10_x64_smp                     4    31     1   r--     885.3 any cpu


________________________________

        From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Zulauf, John
        Sent: Wednesday, January 24, 2007 12:57 PM
        To: xen-devel@xxxxxxxxxxxxxxxxxxx
        Subject: [Xen-devel] Dom0 Hang for large VCPU counts > PCPU
        
        

        We have been experimenting with large VCPU counts >> PCPU and
have succeeded in hanging Dom0 in or during /sbin/loader.

         

        Using xen-3.0.4-testing with an HVM booting the FC6 DVD on a
Core2 Duo (i.e. 2 PCPU) on a 965 chipset

         

        VCPU=17 - works

        VCPU=20 - works (takes a very long time)

        VCPU=24 - lockup (whole machine, yes I mean Dom0)

        VCPU=31 - same

        VCPU=32 - same

         

        We've noted in the Xen l-apic code a hard 32 CPU limit (a uint32
used as an l-apic (vcpu?) bitmask), but this looks to be unrelated.

         

        John Zulauf

        Intel Corporation

         




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