Re: [FFmpeg-devel] [PATCH] ffmpeg_filter: use nb_threads=1 on unused filtergraph

[Michael Niedermayer]

On Sat, Nov 18, 2017 at 11:15:55AM -0500, DeHackEd wrote:
> On 11/18/2017 05:56 AM, Michael Niedermayer wrote:
> > On Thu, Nov 16, 2017 at 08:25:50PM -0500, DeHackEd wrote:
> >> diff --git a/fftools/ffmpeg_filter.c b/fftools/ffmpeg_filter.c
> >> index aacc185..877fd67 100644
> >> --- a/fftools/ffmpeg_filter.c
> >> +++ b/fftools/ffmpeg_filter.c
> >> @@ -340,6 +340,7 @@ int init_complex_filtergraph(FilterGraph *fg)
> >>  graph = avfilter_graph_alloc();
> >>  if (!graph)
> >>  return AVERROR(ENOMEM);
> >> +graph->nb_threads = 1;
> > 
> > if you checked that it doesnt reduce threads for simple & complex
> > graphs that are used then LGTM
> > 
> 
> Yes I have verified that to be the case. Test method was
> $ strace -e trace=clone ./ffmpeg_g -filter_complex 'testsrc2[out]' ...

ok, will apply

thanks

[...]
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Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Frequently ignored answer#1 FFmpeg bugs should be sent to our bugtracker. User
questions about the command line tools should be sent to the ffmpeg-user ML.
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Re: [FFmpeg-devel] [PATCH] ffmpeg_filter: use nb_threads=1 on unused filtergraph

[DeHackEd]

On 11/18/2017 05:56 AM, Michael Niedermayer wrote:
> On Thu, Nov 16, 2017 at 08:25:50PM -0500, DeHackEd wrote:
>> diff --git a/fftools/ffmpeg_filter.c b/fftools/ffmpeg_filter.c
>> index aacc185..877fd67 100644
>> --- a/fftools/ffmpeg_filter.c
>> +++ b/fftools/ffmpeg_filter.c
>> @@ -340,6 +340,7 @@ int init_complex_filtergraph(FilterGraph *fg)
>>  graph = avfilter_graph_alloc();
>>  if (!graph)
>>  return AVERROR(ENOMEM);
>> +graph->nb_threads = 1;
> 
> if you checked that it doesnt reduce threads for simple & complex
> graphs that are used then LGTM
> 

Yes I have verified that to be the case. Test method was
$ strace -e trace=clone ./ffmpeg_g -filter_complex 'testsrc2[out]' ...

The graph is disposed of within the same function. This is why I am proposing
this change.

Number of threads is a complex filtergraph is handled by the parameter
-filter_complex_threads

> thanks
> 
> [...]
> 
> 
> 
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Re: [FFmpeg-devel] [PATCH] ffmpeg_filter: use nb_threads=1 on unused filtergraph

[Michael Niedermayer]

On Thu, Nov 16, 2017 at 08:25:50PM -0500, DeHackEd wrote:
> Hello,
> 
> Simple one-line patch to avoid creating threads on a filtergrpah which does 
> not
> get used during execution. This saves a superfluous thread creation and
> tear-down cycle.
> 
> Besides cleanliness, the main driver for this feature is a system I have 
> access
> to with a large number of cores/threads. Threads count towards ulimits and the
> default of 1 filtergraph thread per CPU thread is undesirable.

>  ffmpeg_filter.c |1 +
>  1 file changed, 1 insertion(+)
> 8900e0a4dfa60c9c6c0f0612489d85080b213db8  
> 0001-ffmpeg_filter-use-nb_threads-1-on-unused-filtergraph.patch
> From 999a38ae38178c2ab3ba8a9ef116e7ec08474302 Mon Sep 17 00:00:00 2001
> From: DHE 
> Date: Thu, 16 Nov 2017 20:09:37 -0500
> Subject: [PATCH] ffmpeg_filter: use nb_threads=1 on unused filtergraph
> 
> Signed-off-by: DHE 
> ---
>  fftools/ffmpeg_filter.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fftools/ffmpeg_filter.c b/fftools/ffmpeg_filter.c
> index aacc185..877fd67 100644
> --- a/fftools/ffmpeg_filter.c
> +++ b/fftools/ffmpeg_filter.c
> @@ -340,6 +340,7 @@ int init_complex_filtergraph(FilterGraph *fg)
>  graph = avfilter_graph_alloc();
>  if (!graph)
>  return AVERROR(ENOMEM);
> +graph->nb_threads = 1;

if you checked that it doesnt reduce threads for simple & complex
graphs that are used then LGTM

thanks

[...]
-- 
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

If you fake or manipulate statistics in a paper in physics you will never
get a job again.
If you fake or manipulate statistics in a paper in medicin you will get
a job for life at the pharma industry.


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