Commit-ID: e53c0994709166b111fbe9162d1a16ece7dfc45b Gitweb: http://git.kernel.org/tip/e53c0994709166b111fbe9162d1a16ece7dfc45b Author: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> AuthorDate: Fri, 24 Jul 2009 14:42:10 +0200 Committer: Ingo Molnar <mingo@xxxxxxx> CommitDate: Sun, 2 Aug 2009 13:47:54 +0200 perf_counter: Collapse inherit on read() Currently the counter value returned by read() is the value of the parent counter, to which child counters are only fed back on child exit. Thus read() can return rather erratic (and meaningless) numbers depending on the state of the child processes. Change this by always iterating the full child hierarchy on read() and sum all counters. Suggested-by: Corey Ashford <cjashfor@xxxxxxxxxxxxxxxxxx> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- kernel/perf_counter.c | 14 +++++++++++++- 1 files changed, 13 insertions(+), 1 deletions(-) diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 9509310..48471d7 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -1688,6 +1688,18 @@ static int perf_release(struct inode *inode, struct file *file) return 0; } +static u64 perf_counter_read_tree(struct perf_counter *counter) +{ + struct perf_counter *child; + u64 total = 0; + + total += perf_counter_read(counter); + list_for_each_entry(child, &counter->child_list, child_list) + total += perf_counter_read(child); + + return total; +} + /* * Read the performance counter - simple non blocking version for now */ @@ -1707,7 +1719,7 @@ perf_read_hw(struct perf_counter *counter, char __user *buf, size_t count) WARN_ON_ONCE(counter->ctx->parent_ctx); mutex_lock(&counter->child_mutex); - values[0] = perf_counter_read(counter); + values[0] = perf_counter_read_tree(counter); n = 1; if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) values[n++] = counter->total_time_enabled + -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html