[Qemu-devel] [PATCH] Fix /perf/nesting coroutine benchmark

[Qemu-devel] [PATCH] Fix /perf/nesting coroutine benchmark

[Gabriel Kerneis]

The /perf/nesting benchmark is broken because the counters are
not reset after each iteration. Therefore, nesting is done only
on the first iteration, and skipped on every other.

This patch fixes the issue, and reduces the number of iterations
to make it possible to run the benchmark in a reasonable amount of
time.

Signed-off-by: Gabriel Kerneis <gabriel@kerneis.info>
---
 tests/test-coroutine.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/tests/test-coroutine.c b/tests/test-coroutine.c
index f4f90ac..668d88f 100644
--- a/tests/test-coroutine.c
+++ b/tests/test-coroutine.c
@@ -182,17 +182,17 @@ static void perf_nesting(void)
     unsigned int i, maxcycles, maxnesting;
     double duration;
 
-    maxcycles = 100000000;
+    maxcycles = 10000;
     maxnesting = 1000;
     Coroutine *root;
-    NestData nd = {
-        .n_enter  = 0,
-        .n_return = 0,
-        .max      = maxnesting,
-    };
 
     g_test_timer_start();
     for (i = 0; i < maxcycles; i++) {
+        NestData nd = {
+            .n_enter  = 0,
+            .n_return = 0,
+            .max      = maxnesting,
+        };
         root = qemu_coroutine_create(nest);
         qemu_coroutine_enter(root, &nd);
     }
-- 
1.8.4.rc3

Re: [Qemu-devel] [PATCH] Fix /perf/nesting coroutine benchmark

[Stefan Hajnoczi]

On Tue, Sep 17, 2013 at 06:26:48PM +0200, Gabriel Kerneis wrote:
> The /perf/nesting benchmark is broken because the counters are
> not reset after each iteration. Therefore, nesting is done only
> on the first iteration, and skipped on every other.
> 
> This patch fixes the issue, and reduces the number of iterations
> to make it possible to run the benchmark in a reasonable amount of
> time.
> 
> Signed-off-by: Gabriel Kerneis <gabriel@kerneis.info>
> ---
>  tests/test-coroutine.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)

Thanks, applied to my block tree:
https://github.com/stefanha/qemu/commits/block

Stefan