[FFmpeg-devel] [PATCH 2/2] Add mutithread function for dnn_backend_native_layer_conv2d.c

[Michael Niedermayer]

On Thu, Sep 03, 2020 at 11:57:24PM +0800, xujunzz at sjtu.edu.cn wrote:
> From: Xu Jun <xujunzz at sjtu.edu.cn>
> 
> Use pthread to multithread dnn_execute_layer_conv2d.
> Can be tested with command "./ffmpeg_g -i input.png -vf \
> format=yuvj420p,dnn_processing=dnn_backend=native:model= \
> espcn.model:input=x:output=y:options=conv2d_threads=23 \
>  -y sr_native.jpg -benchmark"
> 
> before patch: utime=11.238s stime=0.005s rtime=11.248s
> after patch:  utime=20.817s stime=0.047s rtime=1.051s
> on my 3900X 12c24t @4.2GHz
> 
> About the increase of utime, it's because that CPU HyperThreading
> technology makes logical cores twice of physical cores while cpu's
> counting performance improves less than double. And utime sums
> all cpu's logical cores' runtime. As a result, using threads num
> near cpu's logical core's number will double utime, while reduce
> rtime less than half for HyperThreading CPUs.
> 
> Signed-off-by: Xu Jun <xujunzz at sjtu.edu.cn>
> ---
>  .../dnn/dnn_backend_native_layer_conv2d.c     | 92 ++++++++++++++++---
>  1 file changed, 81 insertions(+), 11 deletions(-)

[...]

> +typedef struct thread_param{
> +    thread_common_param *thread_common_param;
> +    int thread_index

semicolon missing


[...]
> +    //join threads, res gets function return
> +    for (int i = 0; i < thread_num; i++){
> +        pthread_join(thread_id[i], &res);

this should be under something like HAVE_PTHREAD_CANCEL

thx

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

He who knows, does not speak. He who speaks, does not know. -- Lao Tsu
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