[libav-devel] [v5] qsvvpp: Fix to perform full init only when needed

Rogozhkin, Dmitry V dmitry.v.rogozhkin at intel.com
Wed Jul 25 18:14:19 CEST 2018


On Tue, 2018-07-24 at 09:53 -0700, Dmitry Rogozhkin wrote:
> On Wed, 2018-07-18 at 14:07 +0200, Maxym Dmytrychenko wrote:
> > Not used VPP sessions, like for hwupload/hwdownload handling,
> > can increase CPU utilization and this patch fixes it.
> > thank you,Joe, for the contribution.
> > 
> > Signed-off-by: Maxym Dmytrychenko <maxim.d33 at gmail.com>
> > ---
> >  libavutil/hwcontext_qsv.c | 72
> > +++++++++++++++++++++++++++++++++++++++++------
> >  1 file changed, 64 insertions(+), 8 deletions(-)
> > 
> > diff --git a/libavutil/hwcontext_qsv.c b/libavutil/hwcontext_qsv.c
> > index b3eb4a3ea..6bc2a38ff 100644
> > --- a/libavutil/hwcontext_qsv.c
> > +++ b/libavutil/hwcontext_qsv.c
> > @@ -23,6 +23,10 @@
> >  
> >  #include "config.h"
> >  
> > +#if HAVE_PTHREADS
> > +#include <pthread.h>
> > +#endif
> > +
> >  #if CONFIG_VAAPI
> >  #include "hwcontext_vaapi.h"
> >  #endif
> > @@ -56,7 +60,13 @@ typedef struct QSVDeviceContext {
> >  
> >  typedef struct QSVFramesContext {
> >      mfxSession session_download;
> > +    int session_download_init;
> >      mfxSession session_upload;
> > +    int session_upload_init;
> > +#if HAVE_PTHREADS
> > +    pthread_mutex_t session_lock;
> > +    pthread_cond_t session_cond;
> > +#endif
> >  
> >      AVBufferRef *child_frames_ref;
> >      mfxFrameSurface1 *surfaces_internal;
> > @@ -146,13 +156,20 @@ static void
> > qsv_frames_uninit(AVHWFramesContext
> > *ctx)
> >          MFXVideoVPP_Close(s->session_download);
> >          MFXClose(s->session_download);
> >      }
> > -    s->session_download = NULL;
> > +    s->session_download      = NULL;
> > +    s->session_download_init = 0;
> >  
> >      if (s->session_upload) {
> >          MFXVideoVPP_Close(s->session_upload);
> >          MFXClose(s->session_upload);
> >      }
> > -    s->session_upload = NULL;
> > +    s->session_upload      = NULL;
> > +    s->session_upload_init = 0;
> > +
> > +#if HAVE_PTHREADS
> > +    pthread_mutex_destroy(&s->session_lock);
> > +    pthread_cond_destroy(&s->session_cond);
> > +#endif
> >  
> >      av_freep(&s->mem_ids);
> >      av_freep(&s->surface_ptrs);
> > @@ -535,13 +552,16 @@ static int qsv_frames_init(AVHWFramesContext
> > *ctx)
> >              s->mem_ids[i] = frames_hwctx->surfaces[i].Data.MemId;
> >      }
> >  
> > -    ret = qsv_init_internal_session(ctx, &s->session_download, 0);
> > -    if (ret < 0)
> > -        return ret;
> > +    s->session_download = NULL;
> > +    s->session_upload   = NULL;
> >  
> > -    ret = qsv_init_internal_session(ctx, &s->session_upload, 1);
> > -    if (ret < 0)
> > -        return ret;
> > +    s->session_download_init = 0;
> > +    s->session_upload_init   = 0;
> > +
> > +#if HAVE_PTHREADS
> > +    pthread_mutex_init(&s->session_lock, NULL);
> > +    pthread_cond_init(&s->session_cond, NULL);
> > +#endif
> >  
> >      return 0;
> >  }
> > @@ -741,6 +761,24 @@ static int
> > qsv_transfer_data_from(AVHWFramesContext *ctx, AVFrame *dst,
> >      mfxSyncPoint sync = NULL;
> >      mfxStatus err;
> >  
> > +    while (!s->session_download_init && !s->session_download) {
> > +#if HAVE_PTHREADS
> > +        if (pthread_mutex_trylock(&s->session_lock) == 0) {
> > +#endif
> > +            qsv_init_internal_session(ctx, &s->session_download,
> > 0);
> > +            s->session_download_init = 1;
+#if HAVE_PTHREADS
> > +            pthread_cond_signal(&s->session_cond);
> 
> You don't need to signal under the mutex. More efficiently is to do
> that without.
> > +            pthread_mutex_unlock(&s->session_lock);
> > +        }
> > +        else {
> > +            pthread_mutex_lock(&s->session_lock);
> > +            pthread_cond_wait(&s->session_cond, &s->session_lock);
> 
> This is incorrect usage of condition variables. Look into example in
> 'man 3 pthread_cond_wait': you should check predicate under the
> mutex.
> > +            pthread_mutex_unlock(&s->session_lock);
> > +        }
> > +#endif
> > +    }
> > +
> 
> As I said the above code is an example of incorrect usage of
> condition
> variables. I believe this should be written in this way:
> 
> #if HAVE_PTHREADS
>     if (pthread_mutex_trylock(&s->session_lock) == 0) {
> #endif
>         qsv_init_internal_session(ctx, &s->session_download, 0);
>         s->session_download_init = 1;
Never do something 2 mins before the meeting. This should probably be:        if (!s->session_download_init) {
            qsv_init_internal_session(ctx, &s->session_download, 0);
            if (s->session_download)
                s->session_download_init = 1;
        }
> #if HAVE_PTHREADS
>         pthread_mutex_unlock(&s->session_lock);
>         pthread_cond_signal(&s->session_cond);
>     } else {
>         pthread_mutex_lock(&s->session_lock);
>         while (!s->session_download_init && !s->session_download) {
>             pthread_cond_wait(&s->session_cond, &s->session_lock);
>         }
>         pthread_mutex_unlock(&s->session_lock);
>     }
> #endif
> 
> > 
> >      if (!s->session_download) {
> >          if (s->child_frames_ref)
> >              return qsv_transfer_data_child(ctx, dst, src);
> > @@ -788,6 +826,24 @@ static int
> > qsv_transfer_data_to(AVHWFramesContext *ctx, AVFrame *dst,
> >      mfxSyncPoint sync = NULL;
> >      mfxStatus err;
> >  
> > +    while (!s->session_upload_init && !s->session_upload) {
> > +#if HAVE_PTHREADS
> > +        if (pthread_mutex_trylock(&s->session_lock) == 0) {
> > +#endif
> > +            qsv_init_internal_session(ctx, &s->session_upload, 1);
> > +            s->session_upload_init = 1;
> > +#if HAVE_PTHREADS
> > +            pthread_cond_signal(&s->session_cond);
> > +            pthread_mutex_unlock(&s->session_lock);
> > +        }
> > +        else {
> > +            pthread_mutex_lock(&s->session_lock);
> > +            pthread_cond_wait(&s->session_cond, &s->session_lock);
> > +            pthread_mutex_unlock(&s->session_lock);
> > +        }
> > +#endif
> > +    }
> > +
> 
> Same comment as above. Correct code would be:
> 
> #if HAVE_PTHREADS
>     if (pthread_mutex_trylock(&s->session_lock) == 0) {
> #endif
>         qsv_init_internal_session(ctx, &s->session_upload, 0);
>         s->session_upload_init = 1;
And here:
        if (!s->session_upload_init) {
            qsv_init_internal_session(ctx, &s->session_upload, 0);
            if (s->session_upload)
                s->session_upload_init = 1;
        }
> #if HAVE_PTHREADS
>         pthread_mutex_unlock(&s->session_lock);
>         pthread_cond_signal(&s->session_cond);
>     } else {
>         pthread_mutex_lock(&s->session_lock);
>         while (!s->session_upload_init && !s->session_upload) {
>             pthread_cond_wait(&s->session_cond, &s->session_lock);
>         }
>         pthread_mutex_unlock(&s->session_lock);
>     }
> #endif
> 
> >      if (!s->session_upload) {
> >          if (s->child_frames_ref)
> >              return qsv_transfer_data_child(ctx, dst, src);


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