Re: [Libvir] [PATCH] BZ#251641: Allow to change the cpu pinning for inactive domain
On Mon, Nov 26, 2007 at 11:12:29AM +0900, Saori Fukuta wrote:
Hi,
I want to change the cpu pinning for inactive domain on RHEL-5.1.
So, I just add the xenXMDomainPinVcpu to xm_internal.c.
We will be allowed to change "cpus" parameter in configuration file
with "vcpupin" command by this patch, like "setmem" or
"setvcpus".
There is 2 things to note:
- This is an effective feature for inactive domain with
Xen3.0.3 (less than 3 of xendConfigVersion).
- On the above environment, the number which specified as
<vcpu> is ignored, because the virtual CPUs is not present
when domain is shut off. So, when executing "vcpupin" command
with this option
# virsh vcpupin Guest 0 1
"0"(vcpu) is ignored and "1"(cpulist) is set to configuration
file
as "cpus".
# cat /etc/xen/Guest | grep cpus
cpus = "1"
Hi Saori,
thanks for looking at this, I think this could be fixed but
there is just a couple of things i feel a bit uneasy with the patch:
- they work with arrays allocated on the stack of fixed
dimention (and rather big), i would rather see a dynamic
allocation of the array to a more reasonnable size and
growing them dynamically
- the repeted use of strcat on each cpu pinning found makes
it a quadratic algorithm though it could really be linear
if one kept a pointer to the current end of the buffer
- the ranges variable is defined in the middle of the function,
this may look notmal in C++ but this is against the conventions
in libvirt C code.
I think the code should be reworked a bit around those lines, but
I have no doubt we can quickly get to a fix in libvirt,
thanks !
Daniel
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