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authorClemens Ladisch <clemens@ladisch.de>2010-11-18 09:53:07 +0100
committerTakashi Iwai <tiwai@suse.de>2010-11-22 08:14:17 +0100
commit47228e48aecdbec423a1275a5e27697d47f1f912 (patch)
treee4a90a134de790626c6da706bda1379eef7b89a6
parent59ff878ffb26bc0be812ca8295799164f413ae88 (diff)
ALSA: pcm: optimize xrun detection in no-period-wakeup mode
Add a lightweight condition on top of the xrun checking so that we can avoid the division when the application is calling the update function often enough. Suggested-by: Jaroslav Kysela <perex@perex.cz> Signed-off-by: Clemens Ladisch <clemens@ladisch.de> Signed-off-by: Takashi Iwai <tiwai@suse.de>
-rw-r--r--sound/core/pcm_lib.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index e9debaabf376..fd18c3c6484f 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -380,6 +380,8 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream,
* the elapsed time to detect xruns.
*/
jdelta = jiffies - runtime->hw_ptr_jiffies;
+ if (jdelta < runtime->hw_ptr_buffer_jiffies / 2)
+ goto no_delta_check;
hdelta = jdelta - delta * HZ / runtime->rate;
while (hdelta > runtime->hw_ptr_buffer_jiffies / 2 + 1) {
delta += runtime->buffer_size;