history write time oddity

Ben Rosengart br+inn at panix.com
Fri May 3 18:30:30 UTC 2002

[Background: I'm building new news servers, they're taking a lot
 of time to do history writes compared to our old servers.]

Bizarrely, tagged-hash turned out to do the trick.

INSTALL says that tagged-hash is desirable when RAM < (10 * tablesize),
but on this system, RAM (in bytes) is more like (40 * tablesize).  Any
idea what could be causing this?

Here's two nights' values for history write, the first without
tagged-hash, the second with.  The difference is dramatic.

Code region              Time    Pct    Invoked   Min(ms)    Avg(ms) Max(ms)
history write    00:40:01.330   2.8%     290583     7.093      8.264 11.578
history write    00:00:50.788   0.1%     395018     0.101      0.129 0.150

Ben Rosengart     (212) 741-4400 x215

1. A robot may not injure entertainment industry profits, or, through inaction,
   allow entertainment industry profits to come to harm.     --Matt McLeod

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