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

Alan Cox (
Wed, 2 Dec 1998 13:19:03 +0000 (GMT)

> On Tue, 1 Dec 1998, Theodore Y. Ts'o wrote:
> > So there are at least a few device drivers which are apparently holding
> > interrupts off long enough so that we lose a clock interrupt. Not good,
> > and one of the reasons why any attempts to tweak the Linux scheduler to
> > make it a "real-time system" simply elicits a smile from me..... oh, if
> > only it were so easy! :-)
> it's not that hard or hopeless as it seems. i wrote a tool for exactly
> this reason, it measures driver delays pretty exactly by instrumenting

Its also far far worse in 2.1.x because of the io lock and the limited
locks available to the networking (notably some network device drivers
trash your performance on a kernel built SMP=1)

Right now 2.0.x is way way better on this paticular count.


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