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...