Paul Tomblin
2010-Jun-30 12:53 UTC
[Xen-users] DomU load average much higher after hardware change
Before: 2 1GHz Pentium III 2 Gb RAM dom0 _mem=96M 3 domUs, one with memory=1000 and vcpus=2, the others with memory=425, vcpus=1 using 2.6.26-2-xen-686 kernel and modules. After: 2 2.8GHz Xeons (with hyperthreading, so it looks like I''ve got 4 cpus in /proc/cpuinfo) 4 Gb RAM dom0_mem=192M 3 domUs, one with memory=2000 and vcpus=2, the others with memory=900, vcpus=1 using 2.6.26-2-xen-amd64 kernel and modules. You''d think that in the "After" case, everything would run much faster, but what I''m finding in the big domU is that my load average is consistently much higher - from being in the 0.2-0.3 range, I''m currently averaging 0.69 according to Munin, although it looks like it''s spending a lot more time in the 1.0+ range than it ever did before. Is there something I''m doing wrong? Should I increase vcpus to 4 and 2 respectively? -- http://www.linkedin.com/in/paultomblin http://careers.stackoverflow.com/ptomblin _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Dustin Henning
2010-Jun-30 13:08 UTC
RE: [Xen-users] DomU load average much higher after hardware change
Are you using the hyperthreads as VCPUs? If so, that could be your problem, I have heard of decent results with them, but also of nightmarish ones. Dustin From: xen-users-bounces@lists.xensource.com [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of Paul Tomblin Sent: Wednesday, June 30, 2010 08:54 To: xen-users@lists.xensource.com Subject: [Xen-users] DomU load average much higher after hardware change Before: 2 1GHz Pentium III 2 Gb RAM dom0 _mem=96M 3 domUs, one with memory=1000 and vcpus=2, the others with memory=425, vcpus=1 using 2.6.26-2-xen-686 kernel and modules. After: 2 2.8GHz Xeons (with hyperthreading, so it looks like I''ve got 4 cpus in /proc/cpuinfo) 4 Gb RAM dom0_mem=192M 3 domUs, one with memory=2000 and vcpus=2, the others with memory=900, vcpus=1 using 2.6.26-2-xen-amd64 kernel and modules. You''d think that in the "After" case, everything would run much faster, but what I''m finding in the big domU is that my load average is consistently much higher - from being in the 0.2-0.3 range, I''m currently averaging 0.69 according to Munin, although it looks like it''s spending a lot more time in the 1.0+ range than it ever did before. Is there something I''m doing wrong? Should I increase vcpus to 4 and 2 respectively? -- http://www.linkedin.com/in/paultomblin http://careers.stackoverflow.com/ptomblin _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
DEMAINE Benoit-Pierre
2010-Jun-30 13:28 UTC
Re: [Xen-users] DomU load average much higher after hardware change
On 30/06/10 14:53, Paul Tomblin wrote:> After: > 2 2.8GHz *Xeons* (with hyperthreading, so it looks like I''ve got 4 cpus in > [...] > using 2.6.26-2-xen- *amd64* kernel and modules.It''s like trying to boot an Alpha with SunOS ... except, Alpha, AMD64, and Xeon are all 4 compatible with x86. In short, you are using your wonderfull machine in "compatible" mode. apt-get install linux-image-xeon you may need to re-install using the apropriate CD ... IA64 if i am right, assuming all recent Xeons are 64b ... -- >o_/ DEMAINE Benoit-Pierre (aka DoubleHP) http://benoit.demaine.info/ If computing were an exact science, IT engineers would''nt have work \_o< "So all that''s left, Is the proof that love''s not only blind but deaf." (FAKE TALES OF SAN FRANCISCO, Arctic Monkeys) _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Paul Tomblin
2010-Jun-30 13:34 UTC
Re: [Xen-users] DomU load average much higher after hardware change
On Wed, Jun 30, 2010 at 9:28 AM, DEMAINE Benoit-Pierre <benoit@demaine.info>wrote:> you may need to re-install using the apropriate CD ... IA64 if i am > right, assuming all recent Xeons are 64b ... >IA64 is the Itanium kernel, it doesn''t boot on Xeons. And there is no "xeon" specific kernel in Debian Stable. -- http://www.linkedin.com/in/paultomblin http://careers.stackoverflow.com/ptomblin _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Dustin Henning
2010-Jun-30 13:38 UTC
RE: [Xen-users] DomU load average much higher after hardware change
I suspect, but do not know, that the x86_64 (even if it''s called AMD64) kernel should work for 64b Xeons if Debian has one. Dustin From: xen-users-bounces@lists.xensource.com [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of Paul Tomblin Sent: Wednesday, June 30, 2010 09:34 To: DEMAINE Benoit-Pierre Cc: xen-users@lists.xensource.com Subject: Re: [Xen-users] DomU load average much higher after hardware change On Wed, Jun 30, 2010 at 9:28 AM, DEMAINE Benoit-Pierre <benoit@demaine.info> wrote: you may need to re-install using the apropriate CD ... IA64 if i am right, assuming all recent Xeons are 64b ... IA64 is the Itanium kernel, it doesn''t boot on Xeons. And there is no "xeon" specific kernel in Debian Stable. -- http://www.linkedin.com/in/paultomblin http://careers.stackoverflow.com/ptomblin _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Paul Tomblin
2010-Jun-30 14:08 UTC
Re: [Xen-users] DomU load average much higher after hardware change
On Wed, Jun 30, 2010 at 9:38 AM, Dustin Henning <Dustin.Henning@prd-inc.com>wrote:> I suspect, but do not know, that the x86_64 (even if it’s called AMD64) > kernel should work for 64b Xeons if Debian has one.That is correct. The original Xeons were just i686 with more L2 cache and built in SMP. The 64 bit Xeons copied AMD''s 64 bit architecture and called it "EM64T" (or "Intel 64"). Debian uses "amd64" as a catch all to refer to both amd64 and em64t. So yes, the -amd64 is the correct kernel to use on 64 bit Xeons. References: http://www.debian.org/doc/manuals/debian-faq/ch-compat.en.html#s-arches "*amd64*: this covers systems based on AMD 64bit CPUs with AMD64 extension and all Intel CPUs with EM64T extension, and a common 64bit userspace." http://en.wikipedia.org/wiki/Xeon "Due to a lack of success with Intel''s Itanium </wiki/Itanium> and Itanium 2 processors, AMD was able to introduce x86-64 </wiki/X86-64>, a 64-bit extension to the x86 architecture </wiki/X86_architecture>. Intel followed suit by including Intel 64 </wiki/Intel_64> (formerly EM64T; it is almost identical to AMD64 </wiki/AMD64>) .... The Xeon was noticeably slower than AMD''s Opteron, although it could be faster in situations where Hyper-Threading came into play. -- http://www.linkedin.com/in/paultomblin http://careers.stackoverflow.com/ptomblin _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users