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Re: Re: [RFC] Virtualization steps [message #2636 is a reply to message #2626]

Thu, 13 April 2006 01:05

Herbert Poetzl
Messages: 239
Registered: February 2006

Senior Member

On Wed, Apr 12, 2006 at 12:28:56PM +0400, Kirill Korotaev wrote:
> Sam,
>
> >Ok, I'll call those three VPSes fast, faster and fastest.
> >
> >"fast" : fill rate 1, interval 3
> >"faster" : fill rate 2, interval 3
> >"fastest" : fill rate 3, interval 3
> >
> >That all adds up to a fill rate of 6 with an interval of 3, but that is
> >right because with two processors you have 2 tokens to allocate per
> >jiffie. Also set the bucket size to something of the order of HZ.
> >
> >You can watch the processes within each vserver's priority jump up and
> >down with `vtop' during testing. Also you should be able to watch the
> >vserver's bucket fill and empty in /proc/virtual/XXX/sched (IIRC)
> >
> >I mentioned this earlier, but for the sake of the archives I'll repeat -
> >if you are running with any of the buckets on empty, the scheduler is
> >imbalanced and therefore not going to provide the exact distribution you
> >asked for.
> >
> >However with a single busy loop in each vserver I'd expect the above to
> >yield roughly 100% for fastest, 66% for faster and 33% for fast, within
> >5 seconds or so of starting those processes (assuming you set a bucket
> >size of HZ).
>
> Sam, what we observe is the situation, when Linux cpu scheduler spreads
> 2 tasks on 1st CPU and 1 task on the 2nd CPU. Std linux scheduler
> doesn't do any rebalancing after that, so no plays with tokens make the
> spread to be 3:2:1, since the lowest priority process gets a full 2nd
> CPU (100% instead of 33% of CPU).
>
> Where is my mistake? Can you provide a configuration where we could test
> or the instuctions on how to avoid this?

well, your mistake seems to be that you probably haven't
tested this yet, because with the following (simple)
setups I seem to get what you consider impossible
(of course, not as precise as your scheduler does it)

vcontext --create --xid 100 ./cpuhog -n 1 100 &
vcontext --create --xid 200 ./cpuhog -n 1 200 &
vcontext --create --xid 300 ./cpuhog -n 1 300 &

vsched --xid 100 --fill-rate 1 --interval 6
vsched --xid 200 --fill-rate 2 --interval 6
vsched --xid 300 --fill-rate 3 --interval 6

vattribute --xid 100 --flag sched_hard
vattribute --xid 200 --flag sched_hard
vattribute --xid 300 --flag sched_hard

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
39 root 25 0 1304 248 200 R 74 0.1 0:46.16 ./cpuhog -n 1 300
38 root 25 0 1308 252 200 H 53 0.1 0:34.06 ./cpuhog -n 1 200
37 root 25 0 1308 252 200 H 28 0.1 0:19.53 ./cpuhog -n 1 100
46 root 0 0 1804 912 736 R 1 0.4 0:02.14 top -cid 20

and here the other way round:

vsched --xid 100 --fill-rate 3 --interval 6
vsched --xid 200 --fill-rate 2 --interval 6
vsched --xid 300 --fill-rate 1 --interval 6

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
36 root 25 0 1304 248 200 R 75 0.1 0:58.41 ./cpuhog -n 1 100
37 root 25 0 1308 252 200 H 54 0.1 0:42.77 ./cpuhog -n 1 200
38 root 25 0 1308 252 200 R 29 0.1 0:25.30 ./cpuhog -n 1 300
45 root 0 0 1804 912 736 R 1 0.4 0:02.26 top -cid 20

note that this was done on a virtual dual cpu
machine (QEMU 8.0) with 2.6.16-vs2.1.1-rc16 and
that there were roughly 25% idle time, which I'm
unable to explain atm ...

feel free to jump on that fact, but I consider
it unimportant for now ...

best,
Herbert

> Thanks,
> Kirill

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[Message index]

		[RFC] Virtualization steps By: dev on Fri, 24 March 2006 17:19
		Re: [RFC] Virtualization steps By: Nick Piggin on Fri, 24 March 2006 17:33
		Re: [RFC] Virtualization steps By: Dave Hansen on Fri, 24 March 2006 19:25
		Re: [RFC] Virtualization steps By: ebiederm on Fri, 24 March 2006 19:53
		Re: [RFC] Virtualization steps By: Bill Davidsen on Tue, 28 March 2006 04:28
		Re: Re: [RFC] Virtualization steps By: kir on Tue, 28 March 2006 06:45
		Re: Re: [RFC] Virtualization steps By: Sam Vilain on Tue, 28 March 2006 21:59
		Re: Re: [RFC] Virtualization steps By: Kir Kolyshkin on Tue, 28 March 2006 22:24
		Re: Re: [RFC] Virtualization steps By: Sam Vilain on Tue, 28 March 2006 23:28
		Re: Re: [RFC] Virtualization steps By: Kirill Korotaev on Wed, 29 March 2006 09:13
		Re: Re: [RFC] Virtualization steps By: Sam Vilain on Wed, 29 March 2006 11:08
		Re: Re: [RFC] Virtualization steps By: Herbert Poetzl on Wed, 29 March 2006 13:45
		Re: Re: [RFC] Virtualization steps By: dev on Wed, 29 March 2006 14:47
		Re: Re: [RFC] Virtualization steps By: Herbert Poetzl on Wed, 29 March 2006 17:29
		Re: Re: [RFC] Virtualization steps By: Sam Vilain on Wed, 29 March 2006 21:37
		Re: Re: [RFC] Virtualization steps By: dev on Wed, 12 April 2006 08:22
		Re: Re: [RFC] Virtualization steps By: Herbert Poetzl on Thu, 13 April 2006 01:05
		Re: Re: [RFC] Virtualization steps By: Kirill Korotaev on Thu, 13 April 2006 06:45
		Re: Re: [RFC] Virtualization steps By: Herbert Poetzl on Thu, 13 April 2006 13:42
		Re: Re: [RFC] Virtualization steps By: Cedric Le Goater on Thu, 13 April 2006 21:33
		Re: Re: [RFC] Virtualization steps By: Herbert Poetzl on Thu, 13 April 2006 22:45
		Re: Re: [RFC] Virtualization steps By: dev on Fri, 14 April 2006 07:35
		Re: Re: [RFC] Virtualization steps By: Cedric Le Goater on Fri, 14 April 2006 09:56
		Re: Re: [RFC] Virtualization steps By: Herbert Poetzl on Sat, 15 April 2006 19:29
		Re: Re: [RFC] Virtualization steps By: kir on Thu, 13 April 2006 22:51
		Re: Re: [RFC] Virtualization steps By: Cedric Le Goater on Fri, 14 April 2006 10:08
		Re: Re: [RFC] Virtualization steps By: Herbert Poetzl on Sat, 15 April 2006 19:31
		Re: [RFC] Virtualization steps By: dev on Tue, 28 March 2006 09:00
		Re: [RFC] Virtualization steps By: Bill Davidsen on Tue, 28 March 2006 14:38
		Re: [RFC] Virtualization steps By: ebiederm on Tue, 28 March 2006 15:03
		Re: [RFC] Virtualization steps By: Jeff Dike on Tue, 28 March 2006 17:47
		Re: [RFC] Virtualization steps By: Sam Vilain on Tue, 28 March 2006 23:07
		Re: [RFC] Virtualization steps By: Bill Davidsen on Wed, 29 March 2006 20:56
		Re: Re: [RFC] Virtualization steps By: Jun OKAJIMA on Tue, 28 March 2006 20:26
		Re: Re: [RFC] Virtualization steps By: kir on Tue, 28 March 2006 20:50
		Re: Re: [RFC] Virtualization steps By: Jun OKAJIMA on Tue, 28 March 2006 21:35
		Re: Re: [RFC] Virtualization steps By: ebiederm on Tue, 28 March 2006 21:51
		Re: Re: [RFC] Virtualization steps By: Sam Vilain on Tue, 28 March 2006 23:17
		Re: [RFC] Virtualization steps By: dev on Tue, 28 March 2006 09:02
		Re: [RFC] Virtualization steps By: Nick Piggin on Tue, 28 March 2006 09:15
		Re: [RFC] Virtualization steps By: Herbert Poetzl on Tue, 28 March 2006 15:35
		Re: [RFC] Virtualization steps By: ebiederm on Tue, 28 March 2006 16:31
		Re: [RFC] Virtualization steps By: Nick Piggin on Tue, 28 March 2006 15:53
		Re: [RFC] Virtualization steps By: Bill Davidsen on Wed, 29 March 2006 21:37
		Re: [RFC] Virtualization steps By: ebiederm on Tue, 28 March 2006 16:15
		Re: [RFC] Virtualization steps By: dev on Wed, 29 March 2006 01:39
		Re: [RFC] Virtualization steps By: Herbert Poetzl on Wed, 29 March 2006 13:47
		Re: Re: [RFC] Virtualization steps By: TheWiseOne on Tue, 28 March 2006 15:48
		Re: Re: [RFC] Virtualization steps By: ebiederm on Tue, 28 March 2006 16:42
		Re: Re: [RFC] Virtualization steps By: TheWiseOne on Tue, 28 March 2006 17:04
		Re: Re: [RFC] Virtualization steps By: Kirill Korotaev on Wed, 29 March 2006 00:55
		Re: [RFC] Virtualization steps By: ebiederm on Fri, 24 March 2006 18:36
		Re: [RFC] Virtualization steps By: Herbert Poetzl on Fri, 24 March 2006 21:19
		Re: [RFC] Virtualization steps By: ebiederm on Mon, 27 March 2006 18:45
		Re: [RFC] Virtualization steps By: dev on Tue, 28 March 2006 08:51
		Re: [RFC] Virtualization steps By: serue on Tue, 28 March 2006 12:53
		Re: [RFC] Virtualization steps By: Sam Vilain on Tue, 28 March 2006 22:50
		Re: [RFC] Virtualization steps By: Dave Hansen on Wed, 29 March 2006 20:30
		Re: [RFC] Virtualization steps By: ebiederm on Wed, 29 March 2006 20:47
		Re: [RFC] Virtualization steps By: Sam Vilain on Wed, 29 March 2006 22:44
		Re: [RFC] Virtualization steps By: dev on Thu, 30 March 2006 13:51
		Re: [RFC] Virtualization steps By: ebiederm on Tue, 28 March 2006 21:58

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