From 7b732a75047738e4f85438ed2f9cd34bf5f2a19a Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 23 Mar 2009 18:22:10 +0100 Subject: perf_counter: new output ABI - part 1 Impact: Rework the perfcounter output ABI use sys_read() only for instant data and provide mmap() output for all async overflow data. The first mmap() determines the size of the output buffer. The mmap() size must be a PAGE_SIZE multiple of 1+pages, where pages must be a power of 2 or 0. Further mmap()s of the same fd must have the same size. Once all maps are gone, you can again mmap() with a new size. In case of 0 extra pages there is no data output and the first page only contains meta data. When there are data pages, a poll() event will be generated for each full page of data. Furthermore, the output is circular. This means that although 1 page is a valid configuration, its useless, since we'll start overwriting it the instant we report a full page. Future work will focus on the output format (currently maintained) where we'll likey want each entry denoted by a header which includes a type and length. Further future work will allow to splice() the fd, also containing the async overflow data -- splice() would be mutually exclusive with mmap() of the data. Signed-off-by: Peter Zijlstra Cc: Paul Mackerras Orig-LKML-Reference: <20090323172417.470536358@chello.nl> Signed-off-by: Ingo Molnar --- arch/powerpc/kernel/perf_counter.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) (limited to 'arch/powerpc') diff --git a/arch/powerpc/kernel/perf_counter.c b/arch/powerpc/kernel/perf_counter.c index e4349281b07d..d48596ab6557 100644 --- a/arch/powerpc/kernel/perf_counter.c +++ b/arch/powerpc/kernel/perf_counter.c @@ -417,8 +417,7 @@ void hw_perf_restore(u64 disable) atomic64_set(&counter->hw.prev_count, val); counter->hw.idx = hwc_index[i] + 1; write_pmc(counter->hw.idx, val); - if (counter->user_page) - perf_counter_update_userpage(counter); + perf_counter_update_userpage(counter); } mb(); cpuhw->mmcr[0] |= MMCR0_PMXE | MMCR0_FCECE; @@ -574,8 +573,7 @@ static void power_perf_disable(struct perf_counter *counter) ppmu->disable_pmc(counter->hw.idx - 1, cpuhw->mmcr); write_pmc(counter->hw.idx, 0); counter->hw.idx = 0; - if (counter->user_page) - perf_counter_update_userpage(counter); + perf_counter_update_userpage(counter); break; } } @@ -702,8 +700,7 @@ static void record_and_restart(struct perf_counter *counter, long val, write_pmc(counter->hw.idx, val); atomic64_set(&counter->hw.prev_count, val); atomic64_set(&counter->hw.period_left, left); - if (counter->user_page) - perf_counter_update_userpage(counter); + perf_counter_update_userpage(counter); /* * Finally record data if requested. -- cgit v1.2.1