On Thu, 2 Mar 2000, Lyle Coder wrote:
> So on an MP system, does Linux use the LOCAL APIC or the 8254 as the actual
> timer tick source... ie... which device actually generates the timer ticks
> (IRQ0)? And what vector does it generate?
What timer tick do you mean?
If that which value is returned as a result of gettimeofday(), then it's
based on 8254. The vector for it is either 0x20, if used in the
compatibility mode and 8259A is involved, or 0x81, if routed through one
of APICs (i.e. as INT2 or INT0 of I/O APIC or LINT0 of one of local
APICs). The counters of these interrupts are shown as "0" in
/proc/interrupts as.
If you mean the scheduling timer than it's that of the local APIC. It
uses vector 0x31. The counters of these are shown as "LOC" in
/proc/interrupts.
-- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available +- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
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