Re: [Ext2-devel] disk throughput

m
2001-11-05T20:28:40Z

Andreas Dilger <adilger@turbolabs.com> writes:
> On Nov 05, 2001 00:04 -0800, Andrew Morton wrote:
[..]
> > With the ialloc.c change, plus the other changes I mentioned
> > the time to create all these directories and files and then run
> > /bin/sync fell from 1:53 to 0:28. Fourfold.
>
> In the end, though, while the old heuristic has a good theory, it _may_
> be that in practise, you are _always_ seeking to get data from different
> groups, rather than _theoretically_ seeking because of fragmented files.
> I don't know what the answer is - probably depends on finding "valid"
> benchmarks (cough).

Another heuristic to try make be to only use a different blockgroup
for when the mkdir()s are seperate in time. i.e. rather than
doing
if ( 0 && ..
use something like
if ((last_time + 100) < jiffes && ...
last_time = jiffies;
which would in theory use the old behaviour for sparodic mkdirs
and the new behaviour for things like 'untar' et al.

M.