linux-kernel - Re: RSDL 0.31 causes slowdown

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Date:	Mon, 26 Mar 2007 11:13:47 +1000
From:	Con Kolivas <kernel@...ivas.org>
To:	tim.c.chen@...ux.intel.com
Cc:	Con Kolivas <ckolivas@...il.com>, ck@....kolivas.org,
	linux-kernel@...r.kernel.org, wli@...omorphy.com,
	suresh.b.siddha@...el.com, arjan@...radead.org
Subject: Re: RSDL 0.31 causes slowdown

On Saturday 24 March 2007 04:57, Tim Chen wrote:
> On Fri, 2007-03-23 at 13:40 +1100, Con Kolivas wrote:
> > Volanomark is a purely yield() semantic dependant workload (as
> > discussed many times previously). In the earlier form of RSDL I
> > softened the effect of sched_yield but other changes since then have
> > made that softness bordering on a noop. Obviously when sched_yield is
> > relied upon that will not be enough. Extending the rr interval simply
> > makes the yield slightly more effective and is not the proper
> > workaround. Since expiration of arrays is a regular frequent
> > occurrence in RSDL then changing yield semantics back to expiration
> > should cause a massive improvement in these values, without making the
> > yields as long as in mainline. It's impossible to know exactly what
> > the final result will be since java uses this timing sensitive yield
> > for locking but we can improve it drastically from this. I'll make a
> > patch soon to change yield again.
>
> Con,
>
> The new RSDL 0.33 has fully recovered the loss in performance for
> Volanomark.  The throughput for Volanomark is at the same level as
> mainline 2.6.21-rc4 kernel.
>
> Tim

Thanks very much for testing. I'm quite happy with the yield semantics staying 
the way they are in rSDl 0.33+.

-- 
-ck
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