From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47157) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XExbh-0008Jh-FO for qemu-devel@nongnu.org; Wed, 06 Aug 2014 05:34:14 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XExbY-0001Ch-DN for qemu-devel@nongnu.org; Wed, 06 Aug 2014 05:34:05 -0400 Received: from mail-qg0-x236.google.com ([2607:f8b0:400d:c04::236]:33826) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XExbY-0001Cd-8g for qemu-devel@nongnu.org; Wed, 06 Aug 2014 05:33:56 -0400 Received: by mail-qg0-f54.google.com with SMTP id z60so2395542qgd.13 for ; Wed, 06 Aug 2014 02:33:55 -0700 (PDT) Sender: Paolo Bonzini From: Paolo Bonzini Date: Wed, 6 Aug 2014 11:33:41 +0200 Message-Id: <1407317621-30591-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH] test-coroutine: add baseline test that times the cost of function calls List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, ming.lei@canonical.com, stefanha@redhat.com This can be used to compute the cost of coroutine operations. In the end the cost of the function call is a few clock cycles, so it's pretty cheap for now, but it may become more relevant as the coroutine code is optimized. For example, here are the results on my machine: Function call 100000000 iterations: 0.173884 s Yield 100000000 iterations: 8.445064 s Lifecycle 1000000 iterations: 0.098445 s Nesting 10000 iterations of 1000 depth each: 7.406431 s One yield takes 83 nanoseconds, one enter takes 97 nanoseconds, one coroutine allocation takes (roughly, since some of the allocations in the nesting test do hit the pool) 739 nanoseconds: (8.445064 - 0.173884) * 10^9 / 100000000 = 82.7 (0.098445 * 100 - 0.173884) * 10^9 / 100000000 = 96.7 (7.406431 * 10 - 0.173884) * 10^9 / 100000000 = 738.9 Signed-off-by: Paolo Bonzini --- tests/test-coroutine.c | 24 ++++++++++++++++ 1 files changed, 24 insertions(+) diff --git a/tests/test-coroutine.c b/tests/test-coroutine.c index 760636d..6e634f4 100644 --- a/tests/test-coroutine.c +++ b/tests/test-coroutine.c @@ -288,6 +288,29 @@ static void perf_yield(void) maxcycles, duration); } +static __attribute__((noinline)) void dummy(unsigned *i) +{ + (*i)--; +} + +static void perf_baseline(void) +{ + unsigned int i, maxcycles; + double duration; + + maxcycles = 100000000; + i = maxcycles; + + g_test_timer_start(); + while (i > 0) { + dummy(&i); + } + duration = g_test_timer_elapsed(); + + g_test_message("Function call %u iterations: %f s\n", + maxcycles, duration); +} + int main(int argc, char **argv) { g_test_init(&argc, &argv, NULL); @@ -301,6 +324,7 @@ int main(int argc, char **argv) g_test_add_func("/perf/lifecycle", perf_lifecycle); g_test_add_func("/perf/nesting", perf_nesting); g_test_add_func("/perf/yield", perf_yield); + g_test_add_func("/perf/function-call", perf_baseline); } return g_test_run(); } -- 1.9.3