From 04da8a43da804723a550f00dd158fd5b5e25ae35 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Tue, 11 Aug 2009 10:40:08 +0200 Subject: perf_counter, x86: Fix/improve apic fallback Johannes Stezenbach reported that his Pentium-M based laptop does not have the local APIC enabled by default, and hence perfcounters do not get initialized. Add a fallback for this case: allow non-sampled counters and return with an error on sampled counters. This allows 'perf stat' to work out of box - and allows 'perf top' and 'perf record' to fall back on a hrtimer based sampling method. ( Passing 'lapic' on the boot line will allow hardware sampling to occur - but if the APIC is disabled permanently by the hardware then this fallback still allows more systems to use perfcounters. ) Also decouple perfcounter support from X86_LOCAL_APIC. -v2: fix typo breaking counters on all other systems ... Reported-by: Johannes Stezenbach Cc: Peter Zijlstra Cc: Mike Galbraith Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo Cc: Frederic Weisbecker LKML-Reference: Signed-off-by: Ingo Molnar --- arch/x86/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/Kconfig') diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 738bdc6b0f8b..13ffa5df37d7 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -24,6 +24,7 @@ config X86 select HAVE_UNSTABLE_SCHED_CLOCK select HAVE_IDE select HAVE_OPROFILE + select HAVE_PERF_COUNTERS if (!M386 && !M486) select HAVE_IOREMAP_PROT select HAVE_KPROBES select ARCH_WANT_OPTIONAL_GPIOLIB @@ -742,7 +743,6 @@ config X86_UP_IOAPIC config X86_LOCAL_APIC def_bool y depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC - select HAVE_PERF_COUNTERS if (!M386 && !M486) config X86_IO_APIC def_bool y -- cgit v1.2.3-59-g8ed1b