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bug#55488: bug#55707: syslogd logging kernel messages slowly?
From: |
Ludovic Courtès |
Subject: |
bug#55488: bug#55707: syslogd logging kernel messages slowly? |
Date: |
Sat, 04 Jun 2022 21:30:24 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/28.1 (gnu/linux) |
Ludovic Courtès <ludo@gnu.org> skribis:
> 2. Explicitly disable syncing for some of the log files by prepending
> a hyphen right before the file name in syslogd.conf (info
> "(inetutils) syslogd invocation").
Tried this (in addition to ‘fdatasync’):
--8<---------------cut here---------------start------------->8---
(define %default-syslog.conf
(plain-file "syslog.conf" "
# Log all error messages, authentication messages of
# level notice or higher and anything of level err or
# higher to the console.
# Don't log private authentication messages!
*.alert;auth.notice;authpriv.none -/dev/console
# Log anything (except mail) of level info or higher.
# Don't log private authentication messages!
*.info;mail.none;authpriv.none /var/log/messages
*.=debug -/var/log/debug
# Same, in a different place.
*.info;mail.none;authpriv.none -/dev/tty12
# The authpriv file has restricted access.
authpriv.* /var/log/secure
# Log all the mail messages in one place.
mail.* -/var/log/maillog
"))
--8<---------------cut here---------------end--------------->8---
In addition to the hyphens, notice that now only debugging info goes to
/var/log/debug (previously everything going to /var/log/messages would
also go to /var/log/debug, which is kinda silly).
This halves the number of ‘fdatasync’ calls and thus doubles the
throughput, but we’re still spending ~0.1s on ‘fdatasync’ for each line,
which is slow.
So the next solution is to not ‘fdatasync’ on /var/log/messages either:
--8<---------------cut here---------------start------------->8---
(define %default-syslog.conf
(plain-file "syslog.conf" "
# Log all error messages, authentication messages of
# level notice or higher and anything of level err or
# higher to the console.
# Don't log private authentication messages!
*.alert;auth.notice;authpriv.none -/dev/console
# Log anything (except mail) of level info or higher.
# Don't log private authentication messages!
*.info;mail.none;authpriv.none -/var/log/messages
# Log \"debug\"-level entries and nothing else.
*.=debug -/var/log/debug
# Same, in a different place.
*.info;mail.none;authpriv.none -/dev/tty12
# The authpriv file has restricted access.
# 'fsync' the file after each line.
authpriv.* /var/log/secure
# Log all the mail messages in one place.
mail.* -/var/log/maillog
"))
--8<---------------cut here---------------end--------------->8---
With this, the system boots much more quickly.
I’m tempted to commit the above syslog.conf. From a look at the code
and doc, it seems that neither rsyslog nor systemd-journald does
anything like “fsync after each logged line”, so the config above sounds
like a reasonable default (at any rate, the current default is
definitely unreasonable on slow spinning disks).
I’m curious to see if it fixes your other boot-up issues, timeouts and
all, Luis.
Ludo’.
- bug#55488: GDM, GNOME: Can't start desktop session after upgrade, Ludovic Courtès, 2022/06/01
- bug#55488: GDM, GNOME: Can't start desktop session after upgrade, Luis Felipe, 2022/06/02
- bug#55488: GDM, GNOME: Can't start desktop session after upgrade, Ludovic Courtès, 2022/06/02
- bug#55488: GDM, GNOME: Can't start desktop session after upgrade, Luis Felipe, 2022/06/02
- bug#55488: GDM, GNOME: Can't start desktop session after upgrade, Ludovic Courtès, 2022/06/03
- bug#55707: bug#55488: GDM, GNOME: Can't start desktop session after upgrade, Ludovic Courtès, 2022/06/04
- bug#55488: bug#55707: syslogd logging kernel messages slowly?, Ludovic Courtès, 2022/06/04
- bug#55488: bug#55707: syslogd logging kernel messages slowly?,
Ludovic Courtès <=
- bug#55488: bug#55707: syslogd logging kernel messages slowly?, Luis Felipe, 2022/06/05
- bug#55707: syslogd logging kernel messages slowly?, Ludovic Courtès, 2022/06/06
- bug#55488: bug#55707: syslogd logging kernel messages slowly?, Luis Felipe, 2022/06/06
- bug#55707: syslogd logging kernel messages slowly?, Ludovic Courtès, 2022/06/06
- bug#55488: GDM, GNOME: Can't start desktop session after upgrade, Luis Felipe, 2022/06/05
- bug#55488: GDM, GNOME: Can't start desktop session after upgrade, Luis Felipe, 2022/06/06
- bug#55488: bug#55707: syslogd logging kernel messages slowly?, Ludovic Courtès, 2022/06/06