readahead changes

[Scott James Remnant]

On Wed, 2006-09-20 at 08:09 -0700, Mike Bird wrote:
> On Tuesday 19 September 2006 21:33, Scott James Remnant wrote:
> >  - the machine was my laptop, a fairly typical P-M which had been
> >    installed with dapper and upgraded through edgy
> 
> With low RAM, readahead may increase startup time as blocks are read
> by readahead, expired from the cache, then read by the normal startup
> process.
> 
The amount of memory used by the default readahead lists is 61.5MB.

> What, if any, are these RAM thesholds for the most common Ubuntu
> configurations?
> 
The recommended RAM for edgy (using the "$500 PC from Dell in April"
metric) is 256MB.


Given the readahead size of 61.5MB, and the average kernel usage of 18M,
that gives us a not unreasonable minimum of 80MB or so for Ubuntu.

This is obviously too high for machines with 64MB of memory or less, but
those I suspect would be using a different derivative which need not
ship readhead (or start so much!).

Also once you've got that little memory, I suspect you won't mind so
much if the boot process takes a few seconds more, or even notice!

Scott
-- 
Scott James Remnant
scott at ubuntu.com
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