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SubjectRe: Dual XEON - >>SLOW<< on SMP
On 2 Nov 2000, Ulrich Drepper wrote:

> I'm seeing this as well, but only with PIII Xeon systems, not PII
> Xeon. Every single timer interrupt on any CPU is accompanied by a NMI
> and LOC increment on every CPU.
> 0: 146727 153389 IO-APIC-edge timer

This is the legacy 8254 timer source, used for the system time, i.e.
gettimeofday() and friends.

> NMI: 300035 300035

This is the NMI watchdog at work. Every tick of the legacy timer all
CPUs receive an NMI unless overridden by the "nmi_watchdog" command line

> LOC: 300028 300028

This is the internal local APIC timer used for scheduling. Every CPU is
equipped with such a private timer.

+ Maciej W. Rozycki, Technical University of Gdansk, Poland +
+ e-mail:, PGP key available +

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