Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755923AbZFWArb (ORCPT ); Mon, 22 Jun 2009 20:47:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753201AbZFWArD (ORCPT ); Mon, 22 Jun 2009 20:47:03 -0400 Received: from bilbo.ozlabs.org ([203.10.76.25]:42802 "EHLO bilbo.ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751912AbZFWArA (ORCPT ); Mon, 22 Jun 2009 20:47:00 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <19008.9265.758076.907649@cargo.ozlabs.ibm.com> Date: Tue, 23 Jun 2009 10:39:13 +1000 From: Paul Mackerras To: Peter Zijlstra Cc: eranian@gmail.com, Ingo Molnar , LKML , Andrew Morton , Thomas Gleixner , Robert Richter , Andi Kleen , Maynard Johnson , Carl Love , Corey J Ashford , Philip Mucci , Dan Terpstra , perfmon2-devel Subject: Re: I.5 - Mmaped count In-Reply-To: <1245674154.19816.228.camel@twins> References: <7c86c4470906161042p7fefdb59y10f8ef4275793f0e@mail.gmail.com> <20090622115239.GF24366@elte.hu> <7c86c4470906220525x409bedadj29be01236e42ea1@mail.gmail.com> <1245674154.19816.228.camel@twins> X-Mailer: VM 8.0.12 under 22.2.1 (i486-pc-linux-gnu) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2296 Lines: 56 Peter Zijlstra writes: > I think we would have to add that do the data page,.. something like the > below? > > Paulus? > > --- > Index: linux-2.6/include/linux/perf_counter.h > =================================================================== > --- linux-2.6.orig/include/linux/perf_counter.h > +++ linux-2.6/include/linux/perf_counter.h > @@ -232,6 +232,10 @@ struct perf_counter_mmap_page { > __u32 lock; /* seqlock for synchronization */ > __u32 index; /* hardware counter identifier */ > __s64 offset; /* add to hardware counter value */ > + __u64 total_time; /* total time counter active */ > + __u64 running_time; /* time counter on cpu */ > + > + __u64 __reserved[123]; /* align at 1k */ > > /* > * Control data for the mmap() data buffer. > Index: linux-2.6/kernel/perf_counter.c > =================================================================== > --- linux-2.6.orig/kernel/perf_counter.c > +++ linux-2.6/kernel/perf_counter.c > @@ -1782,6 +1782,12 @@ void perf_counter_update_userpage(struct > if (counter->state == PERF_COUNTER_STATE_ACTIVE) > userpg->offset -= atomic64_read(&counter->hw.prev_count); > > + userpg->total_time = counter->total_time_enabled + > + atomic64_read(&counter->child_total_time_enabled); > + > + userpg->running_time = counter->total_time_running + > + atomic64_read(&counter->child_total_time_running); Hmmm, when the counter is running, what you want is not so much the total time so far as a way to compute the total time so far from the current TSC/timebase value. So we would need to export tstamp_enabled and tstamp_running plus a scale/offset for converting the TSC/timebase value to nanoseconds consistent with ctx->time. On powerpc that's pretty straightforward because the timebases, but on x86 I gather the offset and maybe also the scale would need to be per-cpu (which is OK, because all the values in the mmapped page are only useful on one specific CPU). How would we compute the scale and offset on x86, given the current TSC value and ctx->time? Paul. -- 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/