> On Jun 17, 2024, at 19:15, Martin Storsjö <[email protected]> wrote:
>
> On Wed, 12 Jun 2024, Zhao Zhili wrote:
>
>> From: Zhao Zhili <[email protected]>
>>
>> Firstly, make ff_kperf_cycles as an implementation of AV_READ_TIME
>> avoids code duplication.
>>
>> Secondly, fix compilation error since 6a18c0bc87e when macos-kperf
>> is enabled. mach_time.h is included only when CONFIG_MACOS_KPERF
>> is 0. The error happened due to define mach_absolute_time as
>> AV_READ_TIME but missing include mach_time.h. Define macos kperf
>> as AV_READ_TIME fixed the issue.
>
> Can you elaborate on what your actual goal is here? We have relatively little
> use of AV_READ_TIME (mostly START/STOP_TIMER), while most benchmarking these
> days is done via checkasm. Do you have a real case where you want to do
> benchmarking with this api, outside of checkasm?
>
> Or do you just want to fix the compilation error? In that case I guess it's
> possible to fix differently by adding the missing includes.
>
> By doing this change, we'd be adding one call to ff_thread_once to every
> single invocation of the timers - which seems suboptimal (even if it probably
> is quite quick). We don't use Linux perf for AV_READ_TIME either, we only use
> it in checkasm. So I'd prefer not to do this change, especially unless you
> have a concrete case where you actively desire to use START/STOP_TIMER
> benchmarking with macOS kperf?
I’m trying to fix the missing include header file first. Then I saw
ff_kperf_init() is called each time by START_TIMER, which can be simplified by
merge ff_kperf_init into ff_kperf_cycles.
#define START_TIMER \
uint64_t tperf; \
ff_kperf_init(); \
tperf = ff_kperf_cycles();
Now I think I have chose the wrong example. checkasm bench_init_kperf is the
right one.
We can remove the ff_thread_once in ff_kperf_init, and let caller make
guarantee to only call it once. But kperf is only for test, so not urgent to do
such change.
Will add missing include in v2.
>
> // Martin
>
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