Re: Scalability requirements for sysv ipc

[Manfred Spraul]

Mike Galbraith wrote:
> On Sat, 2008-03-22 at 15:22 +0100, Manfred Spraul wrote:
>   
> > Mike Galbraith wrote:
> >     
> > > Total: 4691827                                Total: 3942000
> > >   
> > >       
> > Thanks. Unfortunately the test was buggy, it bound the tasks to the 
> > wrong cpu :-(
> > Could you run it again? Actually 1 cpu and 4 cpus are probably enough.
> >     
>
> Sure.  (ran as before, hopefully no transcription errors)
>
>   
Thanks:
sysv sem:
- 2.6.22 had almost linear scaling (up to 4 cores).
- 2.6.24.3 scales to 2 cpus, then it collapses. with 4 cores, it's 75% 
slower than 2.6.22.

sysv msg:
- neither 2.6.22 nor 2.6.24 scale very good. That's more or less 
expected, the message queue code contains a few global statistic 
counters (msg_hdrs, msg_bytes).

The cleanup of sysv is nice, but IMHO sysv sem should remain scalable - 
and a gloal semaphore with IDR can't be as scalable as the RCU protected 
array that was used before.

--
   Manfred
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