Package: at
Version: 3.1.10
Severity: normal
Hello,
When I queue a job with 'batch', atd uses about 60% of the CPU:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
2290 daemon 39 19 1956 468 396 R 59.4 0.1 49:26.18 atd
29963 frederik 35 19 20276 6068 1740 D 21.9 1.2 0:53.27 mencoder
Running 'strace -p 2290' shows that the same system calls are being
repeated over and over again, many times per second:
----------------------------------------------------------------
stat64(".", {st_mode=S_IFDIR|S_ISVTX|0770, st_size=4096, ...}) = 0
open(".", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY) = 4
fstat64(4, {st_mode=S_IFDIR|S_ISVTX|0770, st_size=4096, ...}) = 0
fcntl64(4, F_SETFD, FD_CLOEXEC) = 0
getdents(4, /* 4 entries */, 4096) = 76
stat64("b0002e012f3736", {st_mode=S_IFREG|0700, st_size=5697, ...}) = 0
getdents(4, /* 0 entries */, 4096) = 0
close(4) = 0
open("/proc/loadavg", O_RDONLY) = 4
read(4, "3.52 3.19 3.09 3/252 29879\n", 64) = 27
close(4) = 0
time(NULL) = 1192296108
stat64(".", {st_mode=S_IFDIR|S_ISVTX|0770, st_size=4096, ...}) = 0
open(".", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY) = 4
fstat64(4, {st_mode=S_IFDIR|S_ISVTX|0770, st_size=4096, ...}) = 0
fcntl64(4, F_SETFD, FD_CLOEXEC) = 0
getdents(4, /* 4 entries */, 4096) = 76
stat64("b0002e012f3736", {st_mode=S_IFREG|0700, st_size=5697, ...}) = 0
getdents(4, /* 0 entries */, 4096) = 0
close(4) = 0
open("/proc/loadavg", O_RDONLY) = 4
read(4, "3.52 3.19 3.09 2/252 29879\n", 64) = 27
close(4) = 0
time(NULL) = 1192296108
----------------------------------------------------------------
It seems that 'atd' is in a busy loop reading '/proc/loadavg',
apparently faster than the kernel can update it. This behaviour makes
'batch' quite inefficient. Am I doing something wrong?
-- System Information:
Debian Release: lenny/sid
APT prefers unstable
APT policy: (500, 'unstable'), (500, 'testing'), (500, 'stable'), (1,
'experimental')
Architecture: i386 (i686)
Kernel: Linux 2.6.22-1-686 (SMP w/1 CPU core)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash
Versions of packages at depends on:
ii exim4-daemon-light [mail-tran 4.67-8 lightweight Exim MTA (v4) daemon
ii libc6 2.6.1-5 GNU C Library: Shared libraries
ii libpam0g 0.99.7.1-5 Pluggable Authentication Modules l
ii lsb-base 3.1-24 Linux Standard Base 3.1 init scrip
at recommends no packages.
-- no debconf information
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