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Re: PATCH: Always use ll/sc for mips
- From: "Maciej W. Rozycki" <macro at ds2 dot pg dot gda dot pl>
- To: "H. J. Lu" <hjl at lucon dot org>
- Cc: Ulrich Drepper <drepper at redhat dot com>, linux-mips at oss dot sgi dot com, GNU C Library <libc-alpha at sources dot redhat dot com>
- Date: Wed, 17 Jul 2002 10:31:13 +0200 (MET DST)
- Subject: Re: PATCH: Always use ll/sc for mips
- Organization: Technical University of Gdansk
On Tue, 16 Jul 2002, H. J. Lu wrote:
> > It sucks performance-wise with no visible gain, so I don't think it is
> > really desireable. Since the no-ll/sc case is handled correctly, I see no
>
> Only <sys/tas.h> is covered by the kernel interface. But it doesn't
> cover atomicity.h in glibc and libstdc++.
Even if nobody bothered fixing these, that doesn't mean some other code
is useless. If you don't want to implement these with _test_and_set(),
then just put equivalent ll/sc code there, which will work thanks to the
emulation. Depending on the operation it may even be faster than
_test_and_set() as ll/sc provides a generic way to perform atomic
operations, while using _test_and_set() might require a spinlock.
--
+ Maciej W. Rozycki, Technical University of Gdansk, Poland +
+--------------------------------------------------------------+
+ e-mail: macro@ds2.pg.gda.pl, PGP key available +