Re: Request: I/O request recording

From: Arjan van de Ven
Date: Sat Jan 24 2004 - 17:45:53 EST


On Sat, Jan 24, 2004 at 09:25:45PM +0200, Ville Herva wrote:
> On Sat, Jan 24, 2004 at 07:26:17PM +0100, you [Arjan van de Ven] wrote:
> >
> > I recently did something like this (and it scared me, it seems a typical
> > Fedora boot into gnome opens like 11.000 files ;) but via a printk in
> > the kernel....
> >
> > I experimented with readahead'ing all that stuff while the initscripts
> > ran in the hope it would save time... but it doesn't somehow.
>
> Did you sort the sectors to be read, or just read the files into page cache
> in randomish order ?

semi random order but mostly submitted in parallel so the kernel has lots of
freedom to reorder

> Or do you mean that even after all the files were read into cache, the X
> startup time didn't get any better (not counting the cache priming)?

I mean that the time it takes to prime is just about exactly the time you
then win... eg net gain of about zero

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