ALSA: pcm_lib - optimize wake_up() calls for PCM I/O

As noted by pl bossart <bossart.nospam@gmail.com>, the PCM I/O routines
(snd_pcm_lib_write1, snd_pcm_lib_read1) should block wake_up() calls
until all samples are not processed.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>

diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index fe1b131..e26fb3c 100644 (file)
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -311,6 +311,7 @@ struct snd_pcm_runtime {
        struct snd_pcm_mmap_control *control;
 
        /* -- locking / scheduling -- */
+       unsigned int nowake: 1;         /* no wakeup (data-copy in progress) */
        wait_queue_head_t sleep;
        struct fasync_struct *fasync;
 
@@ -839,6 +840,8 @@ void snd_pcm_set_sync(struct snd_pcm_substream *substream);
 int snd_pcm_lib_interleave_len(struct snd_pcm_substream *substream);
 int snd_pcm_lib_ioctl(struct snd_pcm_substream *substream,
                      unsigned int cmd, void *arg);                      
+int snd_pcm_update_state(struct snd_pcm_substream *substream,
+                        struct snd_pcm_runtime *runtime);
 int snd_pcm_update_hw_ptr(struct snd_pcm_substream *substream);
 int snd_pcm_playback_xrun_check(struct snd_pcm_substream *substream);
 int snd_pcm_capture_xrun_check(struct snd_pcm_substream *substream);

diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index 70a4f74..a632262 100644 (file)
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -263,8 +263,8 @@ static void xrun_log_show(struct snd_pcm_substream *substream)
 
 #endif
 
-static int snd_pcm_update_hw_ptr_post(struct snd_pcm_substream *substream,
-                                     struct snd_pcm_runtime *runtime)
+int snd_pcm_update_state(struct snd_pcm_substream *substream,
+                        struct snd_pcm_runtime *runtime)
 {
        snd_pcm_uframes_t avail;
 
@@ -285,7 +285,7 @@ static int snd_pcm_update_hw_ptr_post(struct snd_pcm_substream *substream,
                        return -EPIPE;
                }
        }
-       if (avail >= runtime->control->avail_min)
+       if (!runtime->nowake && avail >= runtime->control->avail_min)
                wake_up(&runtime->sleep);
        return 0;
 }
@@ -441,7 +441,7 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream,
        if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE)
                snd_pcm_gettime(runtime, (struct timespec *)&runtime->status->tstamp);
 
-       return snd_pcm_update_hw_ptr_post(substream, runtime);
+       return snd_pcm_update_state(substream, runtime);
 }
 
 /* CAUTION: call it with irq disabled */
@@ -1792,6 +1792,7 @@ static snd_pcm_sframes_t snd_pcm_lib_write1(struct snd_pcm_substream *substream,
                goto _end_unlock;
        }
 
+       runtime->nowake = 1;
        while (size > 0) {
                snd_pcm_uframes_t frames, appl_ptr, appl_ofs;
                snd_pcm_uframes_t avail;
@@ -1813,15 +1814,17 @@ static snd_pcm_sframes_t snd_pcm_lib_write1(struct snd_pcm_substream *substream,
                if (frames > cont)
                        frames = cont;
                if (snd_BUG_ON(!frames)) {
+                       runtime->nowake = 0;
                        snd_pcm_stream_unlock_irq(substream);
                        return -EINVAL;
                }
                appl_ptr = runtime->control->appl_ptr;
                appl_ofs = appl_ptr % runtime->buffer_size;
                snd_pcm_stream_unlock_irq(substream);
-               if ((err = transfer(substream, appl_ofs, data, offset, frames)) < 0)
-                       goto _end;
+               err = transfer(substream, appl_ofs, data, offset, frames);
                snd_pcm_stream_lock_irq(substream);
+               if (err < 0)
+                       goto _end_unlock;
                switch (runtime->status->state) {
                case SNDRV_PCM_STATE_XRUN:
                        err = -EPIPE;
@@ -1850,8 +1853,10 @@ static snd_pcm_sframes_t snd_pcm_lib_write1(struct snd_pcm_substream *substream,
                }
        }
  _end_unlock:
+       runtime->nowake = 0;
+       if (xfer > 0 && err >= 0)
+               snd_pcm_update_state(substream, runtime);
        snd_pcm_stream_unlock_irq(substream);
- _end:
        return xfer > 0 ? (snd_pcm_sframes_t)xfer : err;
 }
 
@@ -2009,6 +2014,7 @@ static snd_pcm_sframes_t snd_pcm_lib_read1(struct snd_pcm_substream *substream,
                goto _end_unlock;
        }
 
+       runtime->nowake = 1;
        while (size > 0) {
                snd_pcm_uframes_t frames, appl_ptr, appl_ofs;
                snd_pcm_uframes_t avail;
@@ -2037,15 +2043,17 @@ static snd_pcm_sframes_t snd_pcm_lib_read1(struct snd_pcm_substream *substream,
                if (frames > cont)
                        frames = cont;
                if (snd_BUG_ON(!frames)) {
+                       runtime->nowake = 0;
                        snd_pcm_stream_unlock_irq(substream);
                        return -EINVAL;
                }
                appl_ptr = runtime->control->appl_ptr;
                appl_ofs = appl_ptr % runtime->buffer_size;
                snd_pcm_stream_unlock_irq(substream);
-               if ((err = transfer(substream, appl_ofs, data, offset, frames)) < 0)
-                       goto _end;
+               err = transfer(substream, appl_ofs, data, offset, frames);
                snd_pcm_stream_lock_irq(substream);
+               if (err < 0)
+                       goto _end_unlock;
                switch (runtime->status->state) {
                case SNDRV_PCM_STATE_XRUN:
                        err = -EPIPE;
@@ -2068,8 +2076,10 @@ static snd_pcm_sframes_t snd_pcm_lib_read1(struct snd_pcm_substream *substream,
                xfer += frames;
        }
  _end_unlock:
+       runtime->nowake = 0;
+       if (xfer > 0 && err >= 0)
+               snd_pcm_update_state(substream, runtime);
        snd_pcm_stream_unlock_irq(substream);
- _end:
        return xfer > 0 ? (snd_pcm_sframes_t)xfer : err;
 }
 

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 8e777f7..27284f6 100644 (file)
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -516,6 +516,7 @@ static int snd_pcm_sw_params(struct snd_pcm_substream *substream,
                             struct snd_pcm_sw_params *params)
 {
        struct snd_pcm_runtime *runtime;
+       int err;
 
        if (PCM_RUNTIME_CHECK(substream))
                return -ENXIO;
@@ -540,6 +541,7 @@ static int snd_pcm_sw_params(struct snd_pcm_substream *substream,
                if (params->silence_threshold > runtime->buffer_size)
                        return -EINVAL;
        }
+       err = 0;
        snd_pcm_stream_lock_irq(substream);
        runtime->tstamp_mode = params->tstamp_mode;
        runtime->period_step = params->period_step;
@@ -553,10 +555,10 @@ static int snd_pcm_sw_params(struct snd_pcm_substream *substream,
                if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
                    runtime->silence_size > 0)
                        snd_pcm_playback_silence(substream, ULONG_MAX);
-               wake_up(&runtime->sleep);
+               err = snd_pcm_update_state(substream, runtime);
        }
        snd_pcm_stream_unlock_irq(substream);
-       return 0;
+       return err;
 }
 
 static int snd_pcm_sw_params_user(struct snd_pcm_substream *substream,