Thanks for your input.
Actually, there are no peak moments currently. All four CPUs run at the moment 90+% idle on average.
Code:
Currently Active Users: 100 (31 members and 69 guests)
Code:
8:15am up 6:58, 1 user, load average: 0.31, 0.37, 0.34
99 processes: 96 sleeping, 3 running, 0 zombie, 0 stopped
CPU0 states: 11.8% user, 3.1% system, 0.0% nice, 85.1% idle
CPU1 states: 16.1% user, 1.3% system, 0.0% nice, 82.6% idle
CPU2 states: 0.4% user, 3.1% system, 0.0% nice, 96.5% idle
CPU3 states: 0.1% user, 1.3% system, 0.0% nice, 98.6% idle
We might reach maybe between 1.5 - 2.0 *NIX max during peak times (Friday, Saturday, during the time of European night/late night and North American evening/night when the combined traffic hits us) what is just nice - not causing any delays.
Posts take longer to process than read requests because
a. they have to be parsed, converted to HTML, written twice (once raw, once in HTML format), indexed for the search engine, post counters have to be updated, attachments have to be thumbnailed, &c.
b. the result of these processes has to be inserted into the database and index files, which is a much more intensive operation than to read tables; while this happens, the database has to be locked for writing, in order that no other write requests conflict, overwrite data and corrupt the database - many people updating the database (i. e. by posting, by PMs, by submitting an Arcade score, by giving reputation points, &c.) will cause delays.
c. vB 3 is a very complex and resource-intensive software, and the longer your post is and the more formatting it has, the longer, in general, it takes to parse it and to perform the above-mentioned operations.
d. A thread to which you reply might not be in the write cache.
e. All requests (reading and writing) use the same harddrive; reads enjoy priority over writes.
There is no way to speed this up other than
1. more memory (the more things can be kept in memory, the faster processes become),
2. SCSI-320 harddrives for more speed,
3. harddrives with a larger physical disk cache,
4. mySQL 4 (makes a big difference on large vB3 boards such as Skadi; three times as fast than mySQL 3; we'll install that eventually, once we don't have to give up our security for it.)
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