Performance of 4.x vs 5.x (Re: Lifetime of FreeBSD branches)

[Matthias Buelow]

Kris Kennaway wrote:

>>Hmm... atapci1 is shared with fxp0 on irq 20.. does fxp0 also require
>>the giant lock?
> 
> I don't think so..but the shared interrupt might still be causing some
> other problem.  Try compiling a kernel without fxp support and see if
> you still have the interactive problems under disk load.

Ok, I now have tried a) with HTT switched off in BIOS, b) with HTT off
and without the fxp driver (so that atapci1 is the only driver on irq
20) and c) on a Compaq notebook, all machines running 5.4-stable.
Basically, the problem occurs in all 3 scenarios. However, while cases
a) and b) don't seem to be any different from the original scenario, it
is a lot less pronounced on the notebook (c). In c) the mouse cursor
doesn't really jump but only "feels" a bit like moving thru syrup, and
audio playback (from a remote stream) stops only for fractions of a
second. in a) and b), when moving the mouse, the mouse cursor literally
jumps around on the screen for several seconds many times during disk
i/o, and audio playback stops for ca. 1 second pauses and starts
stuttering, like in the original scenario. Curiously I apparently can
only reproduce it when untarring large archives like
firefox/thunderbird. An ordinary find, or removing the stuff again
doesn't seem to show any of those symptoms.

The machines are: Intel ICH6-based desktop machine, 3ghz p4 ht, sata 
disk, and Intel 440BX, 850mhz p3 notebook, udma33 ata disk.

mkb.