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

[Atsushi SAKAI <sakaia@xxxxxxxxxxxxxx>]

Hi, Keir

I measured it with xentrace on IA64
(Montecito 4pcpu cpu1.4GHz ITC350MHz(in x86 TSC)).
As you know, credit is calculated on BSP with every 30msec.
and its overhead of this patch is about 500count.
This corresponds 1.4usec/30msec(1/20000) overhead on BSP
(other AP is not affected by this patch.)

Anyway, I clean up the code at first.

Thanks
Atsushi SAKAI


Keir Fraser <keir@xxxxxxxxxxxxx> wrote:

> 
> At the very least the coding style needs to be cleaned up to match the rest
> of the file and to fit in 80 columns. Apart from that the new functions
> appear unfeasibly complicated and I'm a little worried abut how much time
> will be spent executing them each scheduling period?
> 
>  -- Keir
> 
> On 8/6/07 11:06, "Atsushi SAKAI" <sakaia@xxxxxxxxxxxxxx> wrote:
> 
> > 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
> > 
> > 
> > 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> 



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel