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Re: Boot poster challenge



On Sun, Nov 21, 2004 at 10:42:45AM -0500, Alan Cox wrote:
> On Sat, Nov 20, 2004 at 11:50:49PM +0100, Ziga Mahkovec wrote:
> > This chart includes data from iostat (sysstat package).  Notice how the
> > disk is fully utilized (%util) during readahead, but the throughput
> > (rkB/s) is *really* low.  This could very well be a problem with my hard
> > disk.  hdparm seems fine though (and I checked the parameters before
> > running readahead).
> 
> Disks are very very seek constrained. You get wonderful performance reading
> linear data. The moment you read a lot of scattered files or a file with a
> lot of segments you will get low performance - even more so on laptops than
> desktops

yeah we saw that; sorting the list on disk sector shaved 2 seconds off...
if we want to save more we'll have to fix the on disk layout to be less
spread out. That's not going to be fun...


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