[cvs] bogofilter/src mime.c,1.33,1.34

[Matthias Andree]

Evgeny Kotsuba <evgen at shatura.laser.ru> writes:

> Well, I don't what to disput - as for me more readable is sizeof(),  you 
> like strlen() - let it be, but then use constat int ;-)
> I agree that this is very little effect on optimization.
> On the other hand  I am not satisfied with 10 messages/sec at Athon and 
> can't find were those inner layers for optimization are.

/Usually/ the limiting factor is I/O speed, and that you won't change
with any optimization. CPUs have become pretty fast, sequential
throughput of drives has improved, but random access is the
bottleneck. Server disk drives rotate faster, with shorter strokes,
making more noise, to improve the number of synchronous operations, and
have more sophisticated queueing (SCSI tagged command queueing).

To find out where the program spends its time, use a decent profiling
tool, Linux has oprofile, Sun touts Solaris 10's DTrace, and there are
other tools.

Even on older machines, strace with timestamps enabled (-tt or -ttt) may
give hints. If it spends a lot of time in open, read, write, fsync,
close, ... you know optimizing the code will help nothing. In that case,
only changing algorithms to reduce the number of synchronous I/O
operations can help then.

-- 
Matthias Andree