Re: [Xen-users] xen cpu affinity, ie; pinning cpus

[Brian Krusic <brian@xxxxxxxxxx>]

On Oct 22, 2009, at 1:13 PM, Tait Clarridge wrote:

> On Thu, 2009-10-22 at 12:24 -0700, Brian Krusic wrote:
> > On Oct 22, 2009, at 12:13 PM, Tait Clarridge wrote:
> >
> > > On Thu, 2009-10-22 at 10:25 -0700, Brian Krusic wrote:
> > > > Hi,
> > > >
> > > >
> > > > Yes, i read several article about having dom0 pinned to 1 cpu.
> > > >
> > > >
> > > > Funny thing is that I do this via xend-config-sxp and grub-conf but
> > > > xm
> > > > vcpu-list still shows dom0 as "any" under affinity column.
> > > >
> > > >
> > > > When I run xm vcpu-pin Domain-0 0 0, xm vcpu-list then shows "0"
> > > > under
> > > > the affinity column until I reboot.
> > > >
> > > >
> > > > Any ideas?
> > > After setting (dom0-cpus 1) in /etc/xen/xend-config.sxp did you
> > > restart
> > > the xend service?
> > >
> > > If I remember correctly, it should be safe to do when domU's are
> > > running.
> > >
> > > This should pin Domain-0 to cpu0.
> > >
> > > eg.
> > >
> > > [root@xxxxxx ]# xm vcpu-list
> > > Name                              ID VCPUs   CPU State   Time(s) CPU
> > > Affinity
> > > Domain-0                           0     0     0   r--  1648038.3 0
> > > Domain-0                           0     1     -   --p       3.1 1
> > > Domain-0                           0     2     -   --p       3.9 2
> > > Domain-0                           0     3     -   --p       3.8 3
> > > Domain-0                           0     4     -   --p       3.7 4
> > > Domain-0                           0     5     -   --p       3.1 5
> > > Domain-0                           0     6     -   --p       3.2 6
> > > Domain-0                           0     7     -   --p       3.6 7
> > > xendomainhere                      1     0     4   -b-  300000.1 any cpu
> > >
> > > That shows that my vm host has 8 cores, but is only using one for
> > > Domain-0.. the rest are in a paused state, so now what I can do is  
> > > pin
> > > them from the config files to use a core from cpus 1-7 or pin the  
> > > domU
> > > to a specific one as well.
> > >
> > > Tait
> > Hi,
> >
> > Heres my grub.conf;
> >
> > kernel /boot/xen.gz-3.4.1 dom0_max_vcpus=1 dom0_mem=1024M
> >
> > xend-config.sxp;
> >
> > (dom0-cpus 1)
> >
> > Heres my xm vcpu-list after a reboot of the system;
> >
> > Name            ID      VCPU    CPU     State   Time(s)         CPU Affinity
> > Domain-0        0       0               0               r--             216.6   
> >         any cpu
> >
> >
> > Heres my xm vcpu-list after xm vcpu-pin;
> >
> > Name            ID      VCPU    CPU     State   Time(s)         CPU Affinity
> > Domain-0        0       0               0               r--             12585.6 
> >         0
> >
> > I tired to format this nice for you so please excuse if it come out
> > like crap.
> >
> > Notice the the CPU Affinity column.
> >
> > Any ideas?
> Well it looks like it is still grabbing cpu0 for Domain-0 to use. Does
> it ever use any other CPU for dom0 before pinning it manually?
Yes, it moves around from proc to proc.

Mostly 0, sometimes, 3,4,6, etc...

Kinda weird.

Just wondering how to interpret this.


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