WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

RE: [Xen-devel] [PATCH] scheduler rate controller

To: "Lv, Hui" <hui.lv@xxxxxxxxx>
Subject: RE: [Xen-devel] [PATCH] scheduler rate controller
From: Dario Faggioli <raistlin@xxxxxxxx>
Date: Fri, 28 Oct 2011 12:09:44 +0200
Cc: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "keir@xxxxxxx" <keir@xxxxxxx>, George Dunlap <George.Dunlap@xxxxxxxxxxxxx>, "Dong, Eddie" <eddie.dong@xxxxxxxxx>, "Duan, Jiangang" <jiangang.duan@xxxxxxxxx>
Delivery-date: Fri, 28 Oct 2011 03:11:19 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
Face: 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
In-reply-to: <C10D3FB0CD45994C8A51FEC1227CE22F3428CB61F2@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <C10D3FB0CD45994C8A51FEC1227CE22F340768D793@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> <CAFLBxZZ9nqeb7CVqTZCsEtJRjgGMTHF2Ak929kvauj2KUFSOyg@xxxxxxxxxxxxxx> <C10D3FB0CD45994C8A51FEC1227CE22F3428CB5EF9@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> <1319789425.19320.12.camel@Abyss> <C10D3FB0CD45994C8A51FEC1227CE22F3428CB61F2@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
On Fri, 2011-10-28 at 16:52 +0800, Lv, Hui wrote:
> > Just something crossed my mind reading the patch and the comments,
> > would it make sense to rate-limit the calls coming from (non-timer)
> > interrupt exit paths while still letting the tick able to trigger a
> > scheduling decision? This just to be sure that at least the time slice
> > enforcing (if any) happens how expected... Could it make sense?
> > 
> 
> Yes, it makes sense. But currently, we lacks the scheduler knowledge such as 
> what caused the scheduler, timer or interrupt? Can we?
> 
Not sure yet, I can imagine it's tricky and I need to dig a bit more in
the code, but I'll let know if I found a way of doing that...

> > More generally speaking, I see how this feature can be useful, and I
> > also think it could live in the generic schedule.c code, but (as George
> > was saying) the algorithm by which rate-limiting is happening needs to
> > be well known, documented and exposed to the user (more than by means
> > of a couple of perf-counters).
> > 
> 
> One question is that, what is the right palace to document such information? 
> I'd like to make it as clear as possible to the users.
> 
Well, don't know, maybe a WARN (a WARN_ONCE alike thing would probably
be better), or in general something that leave a footstep in the logs,
so that one can find out by means of `xl dmesg' or related. Obviously,
I'm not suggesting of printk-ing each suppressed schedule invocation, or
the overhead would get even worse... :-P

I'm thinking of something that happens the very first time the limiting
fires, or maybe oncee some period/number of suppressions, just to remind
the user that he's getting weird behaviour because _he_enabled_
rate-limiting. Hopefully, that might also be useful for the user itself
to fine tune the limiting parameters, although I think the perf-counters
are already quite well suited for this.

> I think I got your point. More considerations should be taken to avoid the 
> disasters to any of the existing schedulers.
> I'm fine to move it to the credit in the current stage. :)
> 
Yeah, and sorry (to everyone) for having pointed that out in so many
messages very similar to each other, but I was having MUA issues and was
thinking my mails weren't making to the list... Sorry again,

Thanks and Regards,
Dario

-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
----------------------------------------------------------------------
Dario Faggioli, http://retis.sssup.it/people/faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)
PhD Candidate, ReTiS Lab, Scuola Superiore Sant'Anna, Pisa  (Italy)

Attachment: signature.asc
Description: This is a digitally signed message part

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