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Re: Once again: test_and_set for CPUs w/o LL/SC

To: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>, "Kevin D. Kissell" <kevink@mips.com>, linux-mips@linux-mips.org
Subject: Re: Once again: test_and_set for CPUs w/o LL/SC
From: Johannes Stezenbach <js@convergence.de>
Date: Wed, 16 Oct 2002 18:30:38 +0200
In-reply-to: <20021016125233.GA25227@convergence.de>
Mail-followup-to: Johannes Stezenbach <js@convergence.de>, "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>, "Kevin D. Kissell" <kevink@mips.com>, linux-mips@linux-mips.org
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20021015172108.GD21220@convergence.de> <Pine.GSO.3.96.1021016140828.14774I-100000@delta.ds2.pg.gda.pl> <20021016125233.GA25227@convergence.de>
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I wrote:

> sysmips is history with current glibc since the Linux kernel emulates
> LL/SC for CPUs that don't have it. This emulation is actually faster than
> sysmips. (You'd think it's slower because it's one syscall vs. two
> emulated instructions. But with LL/SC glibc can use test-and-set
                                                      ^^^^^^^^^^^^
> which enables a more efficient linux-threads mutex implementation.)

Oops, I meant compare-and-swap.


Johannes

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