From: Herbert Xu <herbert@gondor.apana.org.au>
To: mingo@elte.hu (Ingo Molnar)
Subject: Re: Real-Time Preemption and RCU
Cc: bhuey@lnxw.com, paulmck@us.ibm.com, dipankar@in.ibm.com,
       shemminger@osdl.org, akpm@osdl.org, torvalds@osdl.org,
       rusty@au1.ibm.com, tgall@us.ibm.com, jim.houston@comcast.net,
       manfred@colorfullife.com, gh@us.ibm.com, linux-kernel@vger.kernel.org
Organization: Core
In-Reply-To: <20050318160229.GC25485@elte.hu>
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Date: Sat, 19 Mar 2005 09:26:03 +1100
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Ingo Molnar <mingo@elte.hu> wrote:
>
> i really have no intention to allow multiple readers for rt-mutexes. We
> got away with that so far, and i'd like to keep it so. Imagine 100
> threads all blocked in the same critical section (holding the read-lock)
> when a highprio writer thread comes around: instant 100x latency to let
> all of them roll forward. The only sane solution is to not allow
> excessive concurrency. (That limits SMP scalability, but there's no
> other choice i can see.)

What about allowing only as many concurrent readers as there are CPUs?
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Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
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