[FFmpeg-devel] [PATCH v2] checkasm: Test whether the native FFmpeg timers work

[FFmpeg-devel] [PATCH v2] checkasm: Test whether the native FFmpeg timers work

[Martin Storsjö]

On some platforms (in particular, ARM/AArch64), the implementation
of AV_READ_TIME() may use a privileged instruction - in such
cases, benchmarking just fails with a SIGILL.

Instead of crashing, try executing AV_READ_TIME() once within
a region with the signal handler active, to allow gracefully
informing the user about the issue.

This matches the dav1d checkasm commit
95a192549a448b70d9542e840c4e34b60d09b093.
---
Reworded the commit message and the printed warning message, as
the actual type of the timer is undefined and varies across
platforms.
---
 tests/checkasm/checkasm.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/tests/checkasm/checkasm.c b/tests/checkasm/checkasm.c
index 994d64e96b..05f23898d3 100644
--- a/tests/checkasm/checkasm.c
+++ b/tests/checkasm/checkasm.c
@@ -754,6 +754,14 @@ static int bench_init_kperf(void)
 static int bench_init_ffmpeg(void)
 {
 #ifdef AV_READ_TIME
+    if (!checkasm_save_context()) {
+        checkasm_set_signal_handler_state(1);
+        AV_READ_TIME();
+        checkasm_set_signal_handler_state(0);
+    } else {
+        fprintf(stderr, "checkasm: unable to execute platform specific timer\n");
+        return -1;
+    }
     printf("benchmarking with native FFmpeg timers\n");
     return 0;
 #else
@@ -927,7 +935,9 @@ int checkasm_bench_func(void)
 /* Indicate that the current test has failed */
 void checkasm_fail_func(const char *msg, ...)
 {
-    if (state.current_func_ver->cpu && state.current_func_ver->ok) {
+    if (state.current_func_ver && state.current_func_ver->cpu &&
+        state.current_func_ver->ok)
+    {
         va_list arg;
 
         print_cpu_name();
-- 
2.39.3 (Apple Git-145)

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Re: [FFmpeg-devel] [PATCH v2] checkasm: Test whether the native FFmpeg timers work

[Martin Storsjö]

On Thu, 11 Jan 2024, Martin Storsjö wrote:

> On some platforms (in particular, ARM/AArch64), the implementation
> of AV_READ_TIME() may use a privileged instruction - in such
> cases, benchmarking just fails with a SIGILL.
>
> Instead of crashing, try executing AV_READ_TIME() once within
> a region with the signal handler active, to allow gracefully
> informing the user about the issue.
>
> This matches the dav1d checkasm commit
> 95a192549a448b70d9542e840c4e34b60d09b093.
> ---
> Reworded the commit message and the printed warning message, as
> the actual type of the timer is undefined and varies across
> platforms.
> ---
> tests/checkasm/checkasm.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)

Will apply soon.

// Martin
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