From: "Ludovic Courtès" <ludo@gnu.org>
To: Luis Felipe <luis.felipe.la@protonmail.com>
Cc: 55707@debbugs.gnu.org, 55488@debbugs.gnu.org
Subject: bug#55488: bug#55707: syslogd logging kernel messages slowly?
Date: Sat, 04 Jun 2022 21:30:24 +0200 [thread overview]
Message-ID: <87sfokdy5r.fsf_-_@gnu.org> (raw)
In-Reply-To: <878rqcfjcn.fsf@gnu.org> ("Ludovic Courtès"'s message of "Sat, 04 Jun 2022 19:07:20 +0200")
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’.
next prev parent reply other threads:[~2022-06-04 19:31 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-17 18:49 bug#55488: GDM, GNOME: Can't start desktop session after upgrade Luis Felipe via Bug reports for GNU Guix
2022-05-18 8:44 ` Ludovic Courtès
2022-05-18 14:33 ` Luis Felipe via Bug reports for GNU Guix
2022-05-31 9:29 ` Ludovic Courtès
2022-05-31 20:50 ` Luis Felipe via Bug reports for GNU Guix
2022-06-01 19:55 ` Ludovic Courtès
2022-06-02 19:44 ` Luis Felipe via Bug reports for GNU Guix
2022-06-02 21:02 ` Ludovic Courtès
2022-06-02 23:51 ` bug#55707: " Luis Felipe via Bug reports for GNU Guix
2022-06-03 22:54 ` Ludovic Courtès
2022-06-04 17:07 ` Ludovic Courtès
2022-06-04 17:35 ` bug#55488: bug#55707: syslogd logging kernel messages slowly? Ludovic Courtès
2022-06-04 19:30 ` Ludovic Courtès [this message]
2022-06-05 15:25 ` Luis Felipe via Bug reports for GNU Guix
2022-06-06 10:00 ` Ludovic Courtès
2022-06-06 16:31 ` Luis Felipe via Bug reports for GNU Guix
2022-06-06 20:46 ` Ludovic Courtès
2022-06-05 13:19 ` bug#55488: GDM, GNOME: Can't start desktop session after upgrade Luis Felipe via Bug reports for GNU Guix
2022-06-06 18:11 ` Luis Felipe via Bug reports for GNU Guix
2022-06-06 20:50 ` bug#55488: bug#55707: syslogd logging kernel messages slowly? Ludovic Courtès
2022-06-06 23:09 ` bug#55488: GDM, GNOME: Can't start desktop session after upgrade Luis Felipe via Bug reports for GNU Guix
2022-06-06 23:11 ` Luis Felipe via Bug reports for GNU Guix
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