2.6.5, 2.6.6-rc2 sluggish interrupts

[Justin Pryzby]

I noticed this first with Linux 2.6.5 (but not with 2.6.2) and also now
with 2.6.6-rc2.  The machine responds very slugishly while excercizing
one interrupt when another interrupt happens.  Ex.  I'm circling the
mouse pointer around the screen, and suddenly the hard drive decides to
`sync`, or some such.  The pointer then freezes for at least a
half-second.  It affects the keyboard too.  (Though, presumably, it
could also be a display issue).  I notice myself losing alot of
keystrokes as a result of this (I don't know what that means about the
problem..)  I don't know enough to say that this is about interrupts,
but take a look: 

	pryzbyj@andromeda:~$ cat /proc/interrupts 
		   CPU0       
	  0:    3835408          XT-PIC  timer
	  1:       9797          XT-PIC  i8042
	  2:          0          XT-PIC  cascade
	  5:          0          XT-PIC  Maestro3
	  7:          1          XT-PIC  parport0
	  8:          4          XT-PIC  rtc
	  9:          1          XT-PIC  acpi
	 11:     310777          XT-PIC  yenta, yenta, uhci_hcd, eth0, r128@PCI:1:0:0
	 12:      10454          XT-PIC  i8042
	 14:      11802          XT-PIC  ide0
	 15:         17          XT-PIC  ide1
	NMI:          0 
	LOC:          0 
	ERR:          0
	MIS:          0

I don't recall seeing that r128@PCI:1:0:0 entry there before (I haven't
changed hardware, I've been using the console framebuffer for a while,
AGP, DRM have always been on).  And it seems to be making lots of noise
(though I don't know that that's wrong).  I do know there's a general
problem though - sometimes it feels like I'm using a remote machine when
I'm not.

It feels to me like it always happens when the disk is accessed
(possibly just because I can _hear_ that), and it seems like it happens
when the disk hasn't been used in a while.

Please Cc: me.

Justin

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