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Date:      Fri, 11 Mar 2005 23:51:40 +0100
From:      "Daniel Eriksson" <daniel_k_eriksson@telia.com>
To:        "'FreeBSD Current'" <freebsd-current@freebsd.org>
Subject:   Higher interrupt rate after recent SMP/APIC timer changes?
Message-ID:  <!~!UENERkVCMDkAAQACAAAAAAAAAAAAAAAAABgAAAAAAAAA0VcX9IoJqUaXPS8MjT1PdsKAAAAQAAAAeMYUhtckfk+R4a3yIBKgtAEAAAAA@telia.com>

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After the recent changes to the use of APIC timers on SMP systems, the
reported interrupt rate has gone up significantly:

# vmstat -i
interrupt                          total       rate
irq1: atkbd0                           3          0
irq0: clk                       55294842       1998
irq4: sio0                           656          0
irq6: fdc0                            13          0
irq13: npx0                            1          0
irq14: ata0                        28299          1
irq15: ata1                        28144          1
irq17: atapci1+                    60822          2
irq19: atapci3+                    19848          0
irq20: ciss0                      857173         30
irq21: em0                             1          0
irq22: em1                             1          0
lapic1: timer                  110665583       3998
lapic0: timer                  110649350       3998
Total                          277604736      10031

This is an SMP box (dual AMD AthlonMP) running with HZ=2000 and POLLING
enabled. Should I worry about the 4k intr/sec reported for lapic0 and
lapic1, or is this the way things should be?

I should add that system load has not changed noticeably, leading me to
believe that the lapic* interrupt rate is by design and nothing to worry
about. (But I still wanted to ask.)

/Daniel Eriksson




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