Messages in this thread | | | Date | Sat, 16 Mar 2002 18:54:43 -0500 | From | Daniel Jacobowitz <> | Subject | Re: [PATCH] Speedup SMP kernel on UP box |
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On Sat, Mar 16, 2002 at 03:37:26PM -0800, Paul Menage wrote: > In article <0C01A29FBAE24448A792F5C68F5EA47D238DE0@nasdaq.ms.ensim.com>, > you write: > >@@ -9,9 +9,15 @@ > > */ > > > > #ifdef CONFIG_SMP > >-#define LOCK "lock ; " > >+#define LOCK "\n1:\tlock ; " > >+#define LOCK_ADDR "\n" \ > >+ ".section .lock.init,\"a\"\n\t" \ > >+ ".align 4\n\t" \ > >+ ".long 1b\n" \ > >+ ".previous\n" > > > Why not do: > > #define LOCK "1: lock ; \n" \ > ".section .lock.init,\"a\"\n" \ > ".align 4\n"\ > ".long 1b\n"\ > ".previous\n" > > Then you don't need the LOCK_ADDR macro, so most of atomic.h can be > left as is. The assembler doesn't seem to care that there's a section > change between the lock prefix and the instruction that it's locking.
Local labels work forwards as well as backwards:
#define LOCK ".section .lock.init,\"a\"\n" \ ".align 4\n"\ ".long 1f\n"\ ".previous\n" "1: lock ; \n"
I recommend not using "1" for your label, though, because probably other bits of code that use locks have local loops in them. It's to be expected... just pick a less common number.
-- Daniel Jacobowitz Carnegie Mellon University MontaVista Software Debian GNU/Linux Developer - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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