Hi, on an old machine I have with Intel 440BX chipset and PII-266 CPU, I found recent kernels causing MIDI sound output from a Soundblaster Audigy 2 ZS to be varying widely in tempo.
dmesg reports with recent kernels (both those that allow correct playback of MIDI files and those that give wide variation in playback tempo):
Clocksource tsc unstable (delta = 132040172 ns) Switching to clocksource pit
After git-bisection I found:
git bisect bad 109fef9edcc100952eec980acbc2e1295627fbab is the first bad commit commit 109fef9edcc100952eec980acbc2e1295627fbab Author: Clemens Ladisch clemens@ladisch.de Date: Thu Nov 18 09:53:54 2010 +0100
ALSA: timer: automatically load the high-resolution timer
Increase the default timer limit so that snd-hrtimer.ko can be automatically loaded when needed, e.g., when used as the default sequencer timer. This replaces the check for the obsolete CONFIG_SND_HPET.
Signed-off-by: Clemens Ladisch clemens@ladisch.de Signed-off-by: Takashi Iwai tiwai@suse.de
:040000 040000 c7b3b046ea99e563228f36ea4a00f9b763bf5813 741f137a201b31bdf5eaaa58c3031b4b2a68c6d6 M sound
diff --git a/sound/core/timer.c b/sound/core/timer.c index 13afb60..b3aaa60 100644 --- a/sound/core/timer.c +++ b/sound/core/timer.c @@ -34,8 +34,8 @@ #include <sound/initval.h> #include <linux/kmod.h>
-#if defined(CONFIG_SND_HPET) || defined(CONFIG_SND_HPET_MODULE) -#define DEFAULT_TIMER_LIMIT 3 +#if defined(CONFIG_SND_HRTIMER) || defined(CONFIG_SND_HRTIMER_MODULE) +#define DEFAULT_TIMER_LIMIT 4 #elif defined(CONFIG_SND_RTCTIMER) || defined(CONFIG_SND_RTCTIMER_MODULE) #define DEFAULT_TIMER_LIMIT 2 #else
I am currently rebuilding kernel 2.6.38-rc2 with this patch reverted to verify that this commit triggers the problem with this machine.
Arthur.