Re: updatedb

From: Andika Triwidada
Date: Thu Jul 26 2007 - 02:23:17 EST


On 7/26/07, Rene Herman <rene.herman@xxxxxxxxx> wrote:
On 07/25/2007 07:15 PM, Robert Deaton wrote:

> On 7/25/07, Rene Herman <rene.herman@xxxxxxxxx> wrote:

>> And there we go again -- off into blabber-land. Why does swap-prefetch
>> help updatedb? Or doesn't it? And if it doesn't, why should anyone
>> trust anything else someone who said it does says?

> I don't think anyone has ever argued that swap-prefetch directly helps
> the performance of updatedb in any way

People have argued (claimed, rather) that swap-prefetch helps their system
after updatedb has run -- you are doing so now.

> however, I do recall people mentioning that updatedb, being a ram
> intensive task, will often cause things to be swapped out while it runs
> on say a nightly cronjob.

Problem spot no. 1.

RAM intensive? If I run updatedb here, it never grows itself beyond 2M. Yes,
two. I'm certainly willing to accept that me and my systems are possibly not
the reference but assuming I'm _very_ special hasn't done much for me either
in the past.

Might be insignificant, but updatedb calls find (~2M) and sort (~26M).
Definitely not RAM intensive though (RAM is 1GB).


The thing updatedb does do, or at least has the potential to do, is fill
memory with cached inodes/dentries but Linux does not swap to make room for
caches. So why will updatedb "often cause things to be swapped out"?


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