"Expensive timeout(9) function..."

Poul-Henning Kamp phk at phk.freebsd.dk
Tue Apr 1 04:37:49 PST 2003

In message <20030401123319.GA8399 at comp.chem.msu.su>, Yar Tikhiy writes:
>I'm getting the following DIAGNOSTIC messages on my -CURRENT box:
>  Expensive timeout(9) function: 0xc02677e0(0) 0.006095064 s
>(it's uma_timeout(), which triggers the warning once per boot)
>  Expensive timeout(9) function: 0xc0141610(0xc0dfcc00) 0.006581587 s
>  Expensive timeout(9) function: 0xc0141610(0xc0dfcc00) 0.008510173 s
>(and this one is fxp_tick(); it triggers the warning from time to time)
>Are those warnings harmless?

Yes, but indicative of code which needs attention, but harmless.

>As far as my understanding of the issue reaches, a timeout function
>is called under protection of the Giant mutex unless it's marked
>as MP-safe, and that's the reason to spend as little time as possible
>in it.  Right?

Yes, but there are other reasons why you would generally not want
to spend too much time in the timeout function, mostly that it may
screw up other time-critical things in the system.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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