Re: NTP dumps Linux, film at 11. [Fwd/FYI]

Linus Torvalds (
Wed, 2 Dec 1998 10:03:23 -0800 (PST)

On Wed, 2 Dec 1998, Alan Cox wrote:
> Something is dropping the I/O performance across multiple controllers badly
> from 2.0 to 2.1. This includes IDE, AHA1542 and Buslogic scsi combinations.
> It might indeed not be the locks.

Hmm.. I talked to Gerard Roudier, who has always been very
performance-oriented (I think he was the one who did the first real
read-ahead stuff for the page cache, for example). He claimed that 2.1.x
is noticeably faster than 2.0.x on at least Bonnie, and appended some
rather impressive numbers.

That was with his ncr driver, of course.

I obviously don't run 2.0.x kernels anywhere, so..

> For the ISA network cards its fairly obvious where the problems are and
> also extremely hard to fix to get the same results as in 2.0.x (because
> the hardware itself is designed to be single threaded) - but not
> impossible.

Right. Some stuff just wants to be single-threaded, and there isn't much
to be done about that. Locking just adds complexity overhead, and the
extra parallelism in 2.1.x never wins for that case.


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