Re: [FFmpeg-devel] [PATCH] checkasm: Test whether direct cycle counter access works
Le torstaina 11. tammikuuta 2024, 16.15.29 EET Martin Storsjö a écrit : > > AV_READ_TIME() reads time, not cycles. > > Right, I can adjust the wording. Exactly what kind of measurement > AV_READ_TIME returns varies between architectures and environments indeed. In practice, yes, but I would argue that it's a bug if it does not measure time. At the very least because, the name is extremely misleading. > What about: > > checkasm: unable to execute platform specific timer > > > If we want cycle count, then we should add a separate macro, as the two > > are different performance counters at least on RISC-V. > > That's not what I try to do here, I just want to test whether the timer, > whatever we have in AV_READ_TIME, is usable. Sure, I can live with that, but I thought that checkasm actually prefered to measure cycles than time periods. > > As things stand, this code won't do anything on RISC-V, sinec > > AV_READ_TIME() actually reads, well, time, not cycles. > > Should I interpret this, as, the current AV_READ_TIME implementation on > RISC-V always succeeds, contrary to the previous implementation (with > rdcycle) which is unavailable on some systems, referencing > 05115a77e012331b6ff5e24bab40e75848447c62? Yes. -- 雷米‧德尼-库尔蒙 http://www.remlab.net/ ___ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-devel] [PATCH] checkasm: Test whether direct cycle counter access works
On Thu, 11 Jan 2024, Rémi Denis-Courmont wrote:
Le torstaina 11. tammikuuta 2024, 14.53.05 EET Martin Storsjö a écrit :
This should print a nicer error message than crashing due to
an illegal instruction, if direct cycle counter access isn't
allowed.
This matches the dav1d checkasm commit
95a192549a448b70d9542e840c4e34b60d09b093.
---
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..9c5abb53dc 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 access cycle counter\n");
AV_READ_TIME() reads time, not cycles.
Right, I can adjust the wording. Exactly what kind of measurement
AV_READ_TIME returns varies between architectures and environments indeed.
What about:
checkasm: unable to execute platform specific timer
If we want cycle count, then we should add a separate macro, as the two
are different performance counters at least on RISC-V.
That's not what I try to do here, I just want to test whether the timer,
whatever we have in AV_READ_TIME, is usable.
As things stand, this code won't do anything on RISC-V, sinec
AV_READ_TIME() actually reads, well, time, not cycles.
Should I interpret this, as, the current AV_READ_TIME implementation on
RISC-V always succeeds, contrary to the previous implementation (with
rdcycle) which is unavailable on some systems, referencing
05115a77e012331b6ff5e24bab40e75848447c62?
In that case - sure, this would be mostly a no-op for RISC-V, just like it
is for x86, but for ARM/AArch64 it would provide a nicer error message if
access to the relevant registers hasn't been configured.
// Martin
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Re: [FFmpeg-devel] [PATCH] checkasm: Test whether direct cycle counter access works
Le torstaina 11. tammikuuta 2024, 14.53.05 EET Martin Storsjö a écrit :
> This should print a nicer error message than crashing due to
> an illegal instruction, if direct cycle counter access isn't
> allowed.
>
> This matches the dav1d checkasm commit
> 95a192549a448b70d9542e840c4e34b60d09b093.
> ---
> 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..9c5abb53dc 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 access cycle counter\n");
AV_READ_TIME() reads time, not cycles. If we want cycle count, then we should
add a separate macro, as the two are different performance counters at least on
RISC-V. As things stand, this code won't do anything on RISC-V, sinec
AV_READ_TIME() actually reads, well, time, not cycles.
> +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();
--
雷米‧德尼-库尔蒙
http://www.remlab.net/
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[FFmpeg-devel] [PATCH] checkasm: Test whether direct cycle counter access works
This should print a nicer error message than crashing due to
an illegal instruction, if direct cycle counter access isn't
allowed.
This matches the dav1d checkasm commit
95a192549a448b70d9542e840c4e34b60d09b093.
---
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..9c5abb53dc 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 access cycle counter\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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