Re: [gentoo-user] Howzat!

[Mick <michaelkintzios@gmail.com>]

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On Wednesday 20 April 2011 21:06:09 Alan McKinnon wrote:
> Apparently, though unproven, at 15:41 on Wednesday 20 April 2011, Joost
> 
> Roeleveld did opine thusly:
> > Alan,
> > 
> > I would love to do a better test then this.
> > Reason I took Openoffice is because it's known to be a large build
> > (requires a lot of diskspace) and takes a long time.
> > 
> > If you know which other ebuilds might make for a better test, I will be
> > happy to redo the test with those.
> 
> Completely off the top of my head, I can't think of anything that
> extensively uses disk space while compiling. There is the configure step,
> and that hits the disk pretty hard, mostly reads. Building all of KDE
> would fit the bill for disk IO methinks.
> 
> However, you will also hit that infernal disk cache issue and render the
> test useless (it's all in RAM anyway after the first read!). So you would
> have to disable that.
> 
> I don't know how to disable disk caching :-(
> Maybe you can't, the kernel is clearly designed to use the feature if it
> can at all. Maybe there's a knob in /proc you can twiddle.
> 
> Any kernel knob experts around?

No expert here of course, but as long as we are talking about disk buffers 
hdparm used to be able to enable/disable read aheads (A1/A0).  Not sure if 
sdparm does the same for SATA drives, or indeed if it contains any such 
option.
-- 
Regards,
Mick

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