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Date: Mon, 12 Aug 2002 17:57:33 +0200 (CEST)
From: Ingo Molnar <mingo@elte.hu>
Reply-To: Ingo Molnar <mingo@elte.hu>
To: Luca Barbieri <ldb@ldb.ods.org>
Cc: Linus Torvalds <torvalds@transmeta.com>,
       Linux-Kernel ML <linux-kernel@vger.kernel.org>,
       Alexandre Julliard <julliard@winehq.com>
Subject: Re: [patch] tls-2.5.31-C3
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On 12 Aug 2002, Luca Barbieri wrote:

> > > Numbers:
> > > unconditional copy of 2 tls descs: 5 cycles
> > > this patch with 1 tls desc: 26 cycles
> > > this patch with 8 tls descs: 52 cycles
> > 
> > [ 0 tls descs: 2 cycles. ]
> Yes but common multithreaded applications will have at least 1 for
> pthreads.

i would not say 'common' and 'multithreaded' in the same sentence. It
might be so in the future, but it isnt today.

> > how did you calculate this?
> ((26 - 5) / 2000) * 100 ~= 1
> Benchmarks done in kernel mode (2.4.18) with interrupts disabled on a
> Pentium3 running the rdtsc timed benchmark in a loop 1 million times
> with 8 unbenchmarked iterations to warm up caches and with the time to
> execute an empty benchmark subtracted.

old libpthreads or new one?

> > glibc multithreaded applications can avoid the
> > lldt via using the TLS, and thus it's a net win.
> Surely, this patch is better than the old LDT method but much worse than
> the 2-TLS one.

people asked for a 3rd TLS already.

	Ingo

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