IDE performances, 2.4 vs 2.5

From: Stefano Rivoir (
Date: Tue Jun 10 2003 - 04:20:03 EST

Noting that 2.5 is much slower than 2.4 on disk operations (you *touch*
it when you have not-so-fast machine and use KDE, for example), I've
written a silly test that fwrite/fread a single 100Mb file, char by
char, and timing it I have results that I can't understand very well. Of
course, same machine, same hdparm settings, same processes running
(none, it's a notebook without server processes). I've run these test
several time, the results are always more or less the same (ext2):


   read: real 0m15.822s
            user 0m15.180s
            sys 0m0.270s

   write: real 0m12.524s
            user 0m11.800s
            sys 0m0.690s

2.5.70 (up to -bk14, and -mm6)

   read: real 0m20.790s
            user 0m14.372s
            sys 0m0.949s

   write: real 0m13.148s
            user 0m11.901s
            sys 0m0.665

Writing does not drop, but reading has a 6 seconds difference between
user+sys and real that I can't figure out. And the total difference is
"huge". Actually, using anything that touches the disk (it can be a
trivial "aptitude" loading the cache, or a complex KDE) slows down.

I've run these tests on a HP Omnibook w/Celeron, but I have the same
slow down on a Athlon K7.

Is it anyway "normal", something I should expect upgrading from 2.4 to
2.5/2.6? Or there should be something I should check more accurately?

Bye all.

Stefano RIVOIR

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