Subject: [linux-audio-dev] huge latency peaks with 2.4.10-smp kernel
From: Kai Vehmanen (k_AT_eca.cx)
Date: Thu Oct 18 2001 - 17:04:21 EEST
Just in case someone is still wondering why we are constantly talking
about lowlatency kernel patches... Playing an mp3s with ecaplay, running
as root with sched_fifo scheduling, disk i/o done in a separate i/o
thread, smp-machine (usually helps to keep latency-peaks down), minor
system load, I sometimes get the following stats:
(audioio-alsa3) warning! playback underrun - samples lost! Break was at least 8.76 ms long.
(audioio-alsa3) warning! playback underrun - samples lost! Break was at least 1454.97 ms long.
(audioio-alsa3) warning! playback underrun - samples lost! Break was at least 2347.27 ms long.
(audioio-alsa3) warning! playback underrun - samples lost! Break was at least 931.64 ms long.
Engine loop:
Fastest/slowest/average loop time: 0.4/2364.1/5.9 msec.
Disk i/o loop:
Fastest/slowest/average loop time: 0.0/3930.2/0.5 msec.
Just compare the avg and max values! This really is quite amazing -
especially with the usually rock-solid sched-fifo+smp combination.
PS Kernel is standard, non-patched linus-release. Sound driver
is ALSA 0.9b8 (native-iface).
-- http://www.eca.cx Audio software for Linux!
This archive was generated by hypermail 2b28 : Thu Oct 18 2001 - 17:03:13 EEST