Date: Fri, 19 Nov 1999 14:47:21 -0800 (PST) From: Matt Dillon <dillon@FreeBSD.org> To: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/i386/include lock.h Message-ID: <199911192247.OAA01716@freefall.freebsd.org>
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dillon 1999/11/19 14:47:21 PST
Modified files:
sys/i386/include lock.h
Log:
Optimize two cases in the MP locking code. First, it is not necessary
to use a locked cmpexg when unlocking a lock that we already hold, since
nobody else can touch the lock while we hold it. Second, it is not
necessary to use a locked cmpexg when locking a lock that we already
hold, for the same reason. These changes will allow MP locks to be used
recursively without impacting performance.
Modify two procedures that are called only by assembly and are already
NOPROF entries to pass a critical argument in %edx instead of on the
stack, removing a significant amount of code from the critical path
as a consequence.
Reviewed by: Alfred Perlstein <bright@wintelcom.net>, Peter Wemm <peter@netplex.com.au>
Revision Changes Path
1.11 +3 -4 src/sys/i386/include/lock.h
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