I may be interpreting this incorrectly, but are you busy-waiting on the ACPI Global Lock to become free? Bob > -----Original Message----- > From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi- > owner@xxxxxxxxxxxxxxx] On Behalf Of Andreas Mohr > Sent: Wednesday, June 21, 2006 2:01 PM > To: Andrew Morton > Cc: Brown, Len; linux-acpi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Subject: [PATCH -mm 5/6] cpu_relax(): use in ACPI lock > > > Use cpu_relax() in __acpi_acquire_global_lock() etc. > > > This could be considered overkill given the previous unlikely(), > but it is busy-looping in case of false condition after all... > > Tested on 2.6.17-mm1, i386 only (no x86_64 here). > > Signed-off-by: Andreas Mohr <andi@xxxxxxxx> > > > diff -urN linux-2.6.17-mm1.orig/include/asm-i386/acpi.h linux-2.6.17- > mm1.my/include/asm-i386/acpi.h > --- linux-2.6.17-mm1.orig/include/asm-i386/acpi.h 2006-06-19 > 10:57:27.000000000 +0200 > +++ linux-2.6.17-mm1.my/include/asm-i386/acpi.h 2006-06-21 > 14:43:24.000000000 +0200 > @@ -61,11 +61,14 @@ > __acpi_acquire_global_lock (unsigned int *lock) > { > unsigned int old, new, val; > - do { > + while (1) { > old = *lock; > new = (((old & ~0x3) + 2) + ((old >> 1) & 0x1)); > val = cmpxchg(lock, old, new); > - } while (unlikely (val != old)); > + if (likely(val == old)) > + break; > + cpu_relax(); > + } > return (new < 3) ? -1 : 0; > } > > @@ -73,11 +76,14 @@ > __acpi_release_global_lock (unsigned int *lock) > { > unsigned int old, new, val; > - do { > + while (1) { > old = *lock; > new = old & ~0x3; > val = cmpxchg(lock, old, new); > - } while (unlikely (val != old)); > + if (likely(val == old)) > + break; > + cpu_relax(); > + } > return old & 0x1; > } > > diff -urN linux-2.6.17-mm1.orig/include/asm-x86_64/acpi.h linux-2.6.17- > mm1.my/include/asm-x86_64/acpi.h > --- linux-2.6.17-mm1.orig/include/asm-x86_64/acpi.h 2006-06-21 > 14:28:19.000000000 +0200 > +++ linux-2.6.17-mm1.my/include/asm-x86_64/acpi.h 2006-06-21 > 14:43:24.000000000 +0200 > @@ -59,11 +59,14 @@ > __acpi_acquire_global_lock (unsigned int *lock) > { > unsigned int old, new, val; > - do { > + while (1) { > old = *lock; > new = (((old & ~0x3) + 2) + ((old >> 1) & 0x1)); > val = cmpxchg(lock, old, new); > - } while (unlikely (val != old)); > + if (likely(val == old)) > + break; > + cpu_relax(); > + } > return (new < 3) ? -1 : 0; > } > > @@ -75,7 +78,10 @@ > old = *lock; > new = old & ~0x3; > val = cmpxchg(lock, old, new); > - } while (unlikely (val != old)); > + if (likely(val == old)) > + break; > + cpu_relax(); > + } > return old & 0x1; > } > > - > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
