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Re: MIPS_ATOMIC_SET again (Re: newest kernel

To: Florian Lohoff <flo@rfc822.org>
Subject: Re: MIPS_ATOMIC_SET again (Re: newest kernel
From: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Date: Wed, 23 May 2001 21:44:36 +0200 (MET DST)
Cc: Jun Sun <jsun@mvista.com>, Joe deBlaquiere <jadb@redhat.com>, ralf@oss.sgi.com, Pete Popov <ppopov@mvista.com>, George Gensure <werkt@csh.rit.edu>, linux-mips@oss.sgi.com
In-reply-to: <20010523205412.A10981@paradigm.rfc822.org>
Organization: Technical University of Gdansk
Sender: owner-linux-mips@oss.sgi.com
On Wed, 23 May 2001, Florian Lohoff wrote:

> My favourit would be to let the glibc on runtime decide whether
> to use sysmips or ll/sc in the atomic test_and_set stuff. This would
> lead to an common atom op in the userspace which is fast on ll/sc 
> cpus and gives much lesser performance penaltys in the sysmips case
> than emulating ll/sc.

 How would you do it for inlined code?

 Anyway, I consider run-time detection of ll/sc an overkill.  You only
solve a single inefficiency of ISA I code when run on better CPUs.  You
really want to recompile code to make use of new instructions if you care
about performance.

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +


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