Messages in this thread | | | Date | Tue, 11 Aug 2009 18:23:13 +0200 | From | Johannes Stezenbach <> | Subject | Re: [tip:perfcounters/urgent] perf_counter, x86: Fix/improve apic fallback |
| |
On Tue, Aug 11, 2009 at 11:34:21AM +0000, tip-bot for Ingo Molnar wrote: > Commit-ID: 83f19150242ee57730a4331b6ae9a9b90ccc718c > Gitweb: http://git.kernel.org/tip/83f19150242ee57730a4331b6ae9a9b90ccc718c > Author: Ingo Molnar <mingo@elte.hu> > AuthorDate: Tue, 11 Aug 2009 10:40:08 +0200 > Committer: Ingo Molnar <mingo@elte.hu> > CommitDate: Tue, 11 Aug 2009 13:19:07 +0200 > > 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.
Seems to work. From dmesg:
Performance Counters: no APIC, boot with the "lapic" boot parameter to force-enable it. no hardware sampling interrupt available. p6 PMU driver. ... version: 0 ... bit width: 32 ... generic counters: 2 ... value mask: 00000000ffffffff ... max period: 000000007fffffff ... fixed-purpose counters: 0 ... counter mask: 0000000000000003 CPU: Intel(R) Pentium(R) M processor 1.80GHz stepping 06
However:
oprofile: using timer interrupt.
I tried "perf top", "perf stat -a sleep 1", "perf stat java foo", it all looks good to my untrained eye.
Thanks, Johannes
| |