[ILUG] Updatedb

[Vincent Cunniffe]

>Mornin',
> I've just seen my highest load ever on my 486 linux box - 17.68 :-) I
>had set updatedb set to run 3 times a week, but for some reason it
>decided that it would launch itself ~35 times and really grind the disk.
>After about an hour I noticed that the machine was reeeaaallllyy slow,
>and the hard drive was still grinding. Doh!! I was using linuxconf, but
>it's obviously not as foolproof as I'd hoped :-)

Last year, while testing my final year project in TCD, I was using a 
Solaris machine (Ultra 5, 64MB). The project consisted of a server
and a set of clients, and I was testing the system by trying to make
the server allocate a *serious* load of memory blocks to see what 
would happen. I'm not sure exactly how many memory blocks it
allocated, but it was roughly in the region of 5-10 million small blocks ;-)

Main memory and almost all of the swapspace filled up, but the problem
was that towards the end of the allocations, when it had a few million
kernel memory allocation records to search through, it started having
to page everything out and in again repeatedly.

Then it ran through the process of deallocating it all again :-)

It effectively locked down the machine for 1.5 hours or so, paging
constantly for the entire time. It took several minutes for it to open a
telnet connection from the adjacent machine, and over a minute to
get top started.

However, I was extremely pleased and impressed that neither Solaris
nor my server crashed : damn nice piece of engineering.

Vin