Re: [Xen-devel] [PATCH][RFC] consider weight for vcpu-pin case

[Atsushi SAKAI <sakaia@xxxxxxxxxxxxxx>]

Hi, Keir

Thanks for your reply,

Keir Fraser <keir@xxxxxxxxxxxxx> wrote:
> The patch fixes sched-credit vcpu weighting somehow, I guess. How does it do
> this?


For example Xen boots on 8core machine(like Xeon Quad core X 2)
Somebody plan to use 2pcpu for development use, and 2pcpu x 3 for customer use.

example (d0 means Domain0 v0 means vcpu0)
d0v0 d0v1 d0v2 d0v3 d0v4(not pinned)    idle
d1v0 d1v1 (pinned 0-1 with weight=256) running CPU intensive process.
d2v0 d2v1 (pinned 0-1 with weight=512) running CPU intensive process.
d3v0 d3v1 (pinned 2-3 with weight=256) idle
d4v0 d4v1 (pinned 4-5 with weight=256) idle
d5v0 d5v1 (pinned 6-7 with weight=256) idle


(if you see in xentop)
   before  after(applying this patch)
d0   0.0     0.0
d1 100.0    66.0
d2 100.0   134.0
d3   0.0     0.0
d4   0.0     0.0
d5   0.0     0.0

In this case d1 credit sum is 80msec, and d2 credit sum is 160msec.(30msec x 
8pcpu in Xen)
But available CPU resources is just 60msec(since 2domains are pinned to 2pcpu).
so each pcpu credit value is overflow(>30msec)
This makes cannot allocate CPU resources based on CPU weight.
Just equally allocate d1 and d2 CPU resources.
(I think this is current CREDIT scheduler problem)

Thanks
Atsushi SAKAI



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