Re: [Xen-devel] [PATCH] tunable time slice for credit scheduler

[Atsushi SAKAI <sakaia@xxxxxxxxxxxxxx>]

Hi, Keir and Emmanuel

 Thanks for reviewing.
I am very happy to get a comment on this.

Primary motivation of this patch is 
Network benchmark(Web server throughput) at Xen.
(Which is presented on XenSummit 2007 Spring)

In this comparison, 
network through put is not good if you use credit scheduler
http://www.xensource.com/files/xensummit_4/3schedulers-xen-summit_Cherkosova.pdf

In this presentation, SEDF and BVT selects the best parameter before 
comparison.(p.9)
On the other hand, Credit Scheduler does not have such kind of 
tunable paramter.
I think the comparison is not fare.
This patch adds this kind of parameter for fare comparison.

And I think time slice should be differenciated by 
Dom0, DriverDomain and Others.
So I make this patch defining each domain timeslice. 
But as a first step, global time slice is a good idea.


Anyway, this is not related to VNC issue.

Thanks
Atsushi SAKAI


Keir Fraser <keir@xxxxxxxxxxxxx> wrote:

> I'm not sure that extra parameters are what the scheduler really needs.
> Tuning for better performance 'out of the box' would be more useful. Under
> what circumstances were you seeing VNC connection timeouts? If it's an
> extreme overload situation then that can likely be detected and dealt with
> by automatic time-slice adjustment. I can't see a time-slice option being
> used sensibly in many scenarios.
> 
>  -- Keir
> 
> On 27/6/07 13:08, "Emmanuel Ackaouy" <ackaouy@xxxxxxxxx> wrote:
> 
> > The sched_credit.c part of this patch looks good to me (except for
> > the coding style issues). Before adding per-domain tunable time
> > slices though, shouldn't we make the global time slice tunable?
> > 
> > 
> > On May 17, 2007, at 10:25, Atsushi SAKAI wrote:
> > 
> >> Hi,
> >> 
> >> This patch intends to add tunablity for time slice on credit scheduler.
> >> Each domain can change time slice.
> >> 
> >> for example,
> >> xm sched-credit -d 0 -s 20
> >> (unit is msec)
> >> 
> >> Signed-off-by: Atsushi SAKAI <sakaia@xxxxxxxxxxxxxx>
> >> 
> >> c.f.
> >> 1)libxc(pyxc) forgets help message for cap.
> >> I add it on tools/python/xen/lowlevel/xc/xc.c
> >> 
> >> 2)time slice can set from 1 to 100(msec).
> >> I have see VNC connection timeout problem for many domain on one CPU.
> >> For this reason, it can set time slice from 1 to 100 msec.
> >> Of course, default value is 30msec.
> >> 
> >> 
> >> Thanks
> >> Atsushi SAKAI
> >> 
> >> <tune_timeslice.patch>_______________________________________________
> >> Xen-devel mailing list
> >> Xen-devel@xxxxxxxxxxxxxxxxxxx
> >> http://lists.xensource.com/xen-devel
> > 
> > 
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> 
> 
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