I have a full duplex voice application, that records voice and sends (over a network) as well as receives and plays voice. OSS APIs are used to capture and play voice samples.

The voice quality is noticeably poor in SUSE 10. After further investigation, I see most of the 'read' system calls fail with EAGAIN (resource unavailable) error. This is not the case in SUSE 9.2.
This results in poor voice quality -- broken voice, due to loss of voice samples.

Please take a look at the strace stats below for SUSE 9.2 and 10. Check the errors column for SUSE 10.
SUSE 9.2
Process 17533 detached
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
51.54 0.824285 48 17152 gettimeofday
14.36 0.229609 52 4393 693 select
9.85 0.157454 76 2081 692 sigreturn
7.89 0.126199 14 8784 rt_sigprocmask
7.74 0.123765 20 6201 ioctl
4.31 0.068929 33 2067 read
4.31 0.068898 33 2067 write
0.01 0.000083 6 14 alarm
0.00 0.000034 11 3 munmap
0.00 0.000007 4 2 rt_sigaction
0.00 0.000003 3 1 1 open
------ ----------- ----------- --------- --------- ----------------
100.00 1.599266 42765 1386 total


SUSE 10
Process 11342 detached
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
49.58 1.006722 1 1191090 1189103 read
49.44 1.003873 1 1194607 ioctl
0.95 0.019285 11 1698 write
0.02 0.000453 0 1152 551 select
0.00 0.000038 13 3 munmap
0.00 0.000015 0 9230 gettimeofday
0.00 0.000000 0 1 1 open
0.00 0.000000 0 11 alarm
0.00 0.000000 0 793 624 sigreturn
0.00 0.000000 0 6 sched_yield
0.00 0.000000 0 2 rt_sigaction
0.00 0.000000 0 2303 rt_sigprocmask
------ ----------- ----------- --------- --------- ----------------
100.00 2.030386 2400896 1190279 total
BTW, the SUSE 10 machine runs on newer hardware with on board Intel HDA Sound (Realtek ALC262).

Any thoughts on what causes so many read failures? Could this be hardware/driver related? There is nothing fancy about this sound card, its a regular on board card. It would be great if someone can confirm their experience with this card.

Any suggestions are also most welcome...

Thanks for the help.