Newsgroups: news.software.b
Path: utzoo!utstat!geoff
From: geoff@utstat.uucp (Geoff Collyer)
Subject: Re: news software speedup
Message-ID: <1988Mar27.214812.3062@utstat.uucp>
Summary: crank up buffer cache to make dbm run faster
Keywords: dbm
Organization: Statistics, U. of Toronto
References: <649@bms-at.UUCP> <10150@ncc.UUCP> <4246@hoptoad.uucp>
Date: Sun, 27 Mar 88 21:48:12 GMT

I rebuilt the dbm history files from the ASCII history file on dalcs
(a Sun 4 with 32Mb of main memory) in 23 seconds elapsed time.  dalcs
gets a full news feed and it took five minutes just to build the ASCII
history file using find and some small filters.  With 32Mb of memory,
the buffer cache was 3.2Mb, and that gives essentially the same speedup
that John Gilmore proposed to achieve by modifying dbm itself.

I recently increased the buffer cache on our file servers to 25% of
available memory rather than 10%, as the servers used to have plenty of
free memory, even at busy times.  (Those of you on Suns can just patch
_bufpages in /vmunix to be the number of pages to devote to the cache,
then reboot.)  I haven't timed expire recently and in any case we get
a small news feed here.
-- 
Geoff Collyer	utzoo!utstat!geoff, utstat.toronto.{edu,cdn}!geoff