furio ercolessi (furio@spin.it)
Fri, 08 Jan 1999 2:51:42 MET
> On Fri, 8 Jan 1999, furio ercolessi wrote:
>
> > > > However, I am rather unhappy with the amount of CPU which
> > > > syslogd seems to use under normal circumstances.
> > > > For instance, right now I observe a syslogd using about 60-70%
> > > > of a 533MHz LX to write about 13kB per minute on a file.
> > > > This is ridiculous. Heck, in this case the messages are generated
> > > > by sendmail, which does that while cruising along at 0.1% CPU.
> > > >
> > Still, the cost of sync'ing a file cannot be that high.
> > I believe that this behavior suggests the presence of some other can
> > of worms somewhere, which somebody may like to open ;-)
>
> It really is that high. Syslogd writes to disk after every message (usually
> every line), so 13k/min is ~130 writes/s.
I meant 13 kbytes per minute, or ~200 bytes/s or ~3 messages/s.
I also administer an HP 710/50 MHz (1993 or 1994) that handles a
comparable load rather comfortably, and the CPU is some factor 20
less powerful.
> When data is NOT synced, this
> means that it is not physically on disk. i.e. if the system crashes, the
> only data on disk will be since the last sync. (The kernel automatically
> syncs at regular intervals...every few minutes, IIRC)
>
> In other words, make sure kernel messages go to a file that gets synced, or
> you could be in for trouble. :)
Yes; however, after the configuration change the log files seems synced
anyway, only without the CPU overhead. Strange.
Another, perhaps related symptom I observed is that the "sync" command
may take a rather long time to execute (of the order of 30 seconds).
Isn't that a bit too much?
> Have you (or anyone else) noticed syslogd crashing regularly? Mine crashes
> like every 2-3 days, and I have to restart it.
No, mine runs healthy :-)
root 184 1.0 0.2 3160 560 ? S Nov 21 740:43 syslogd
furio ercolessi
Spin - Trieste
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