Messages in this thread | | | Date | Mon, 27 Jan 2003 22:40:34 -0500 (EST) | From | Bill Davidsen <> | Subject | Re: 2.5.59-mm5: cpu1 not working |
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On Mon, 27 Jan 2003 jordan.breeding@attbi.com wrote:
> > On Mon, 27 Jan 2003 16:34:22 -0500 (EST) > > Bill Davidsen <davidsen@tmr.com> wrote: > > > > > That's the thing I would expect to see if you used 'noapic' and watchdog. > > > I posted over the weekend that I have been seeing some inobvious results > > > to IPC benchmarking with scombinations of noapic and watchdog, but I > > > didn't snap the interrupts. I'll be happy to add that to my list of stuff > > > to try next weekend, but the box is not a toy during the week, and I would > > > have a five hour round trip drive if a reboot failed, so I'll pass on > > > trying it until I'll in the same room. > > > > no "noapic" here: > > > > kernel /boot/linux-2.5.59-mm5 root=/dev/hda5 ro vga=0x30a profile=2 > > nmi_watchdog=1
> There was a seperate thread about this a couple of days ago. It boils > down to this: if there isn't sufficient load on your CPUs then it is > both easier and faster to have one CPU handle all of the interrupts, if > there is sufficient load on your CPUs then the kirq patch distributes > the interrupts accordingly. I can verify that this behavior is > consisent with what I see on my dual Xeon box (shows up as 4 ht capable > CPUs). As long as your second CPU is showing up in /proc/cpuinfo and in > top then the CPU is working it just isn't having to handle any > interrupts yet.
The reason I mentioned noapic is that when running with the apic I see a very good balance on a system with minimal load other than CPU. Since there was a count on NMI the watchdog was clearly on. But on my test system, I just check the count and the balance is very good:
Script started on Mon Jan 27 22:38:37 2003 bash-2.05a$ uname -a Linux bilbo.tmr.com 2.5.59 #6 SMP Sat Jan 25 19:46:18 EST 2003 i686 unknown bash-2.05a$ cat /proc/interrupts CPU0 CPU1 0: 88705542 91864773 IO-APIC-edge timer 1: 853 850 IO-APIC-edge i8042 2: 0 0 XT-PIC cascade 3: 7752 7269 IO-APIC-edge NE2000 8: 1 1 IO-APIC-edge rtc 9: 0 0 IO-APIC-level uhci-hcd 11: 24218 28443 IO-APIC-level ide2 12: 26 26 IO-APIC-edge i8042 14: 664226 665346 IO-APIC-edge ide0 15: 1 1 IO-APIC-edge ide1 NMI: 0 0 LOC: 180596403 180596410 ERR: 25 MIS: 0 bash-2.05a$ exit
Script done on Mon Jan 27 22:39:00 2003
The system is up >24hr, so the irq counts reflect very little io. Running noapic obviously puts all the ints on CPU0.
-- bill davidsen <davidsen@tmr.com> CTO, TMR Associates, Inc Doing interesting things with little computers since 1979.
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