Date: Tue, 24 May 2005 10:15:17 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Hellwig <hch@infradead.org>, Daniel Walker <dwalker@mvista.com>,
       linux-kernel@vger.kernel.org, akpm@osdl.org, sdietrich@mvista.com
Subject: Re: RT patch acceptance
Message-ID: <20050524081517.GA22205@elte.hu>
References: <1116890066.13086.61.camel@dhcp153.mvista.com> <20050524054722.GA6160@infradead.org> <20050524064522.GA9385@elte.hu> <4292DFC3.3060108@yahoo.com.au>
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* Nick Piggin <nickpiggin@yahoo.com.au> wrote:

> Of course this is weighed off against the improvements added to the
> kernel. I'm personally not too clear on what those improvements are; a
> bit better soft-realtime response? (I don't know) [...]

what the -RT kernel (PREEMPT_RT) offers are guaranteed hard-realtime 
responses. ~15 usecs worst-case latency on a 2GHz Athlon64. On arbitrary 
(SCHED_OTHER) workloads. (I.e. i've measured such worst-case latencies 
when running 1000 hackbench tasks or when swapping the box to death, or 
when running 40 parallel copies of the LTP testsuite.)

so it's well worth the effort, but there's no hurry and all the changes 
are incremental anyway. I can understand Daniel's desire for more action 
(he's got a product to worry about), but upstream isnt ready for this 
yet.

	Ingo
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