Hi, Do we have any knobs in FreeBSD to reduce the interrupt latency? I am currently seeing performance differences between 8.x and 7.x. Anyone have any ideas? --HPS On Wednesday 04 March 2009, Artyom Mirgorodsky wrote: > >Repeat the same test using FreeBSD -current. > > > >a) On the machine where it is slow. > > vmstat -i ; sleep 1 ; vmstat -i > interrupt total rate > irq1: atkbd0 233 2 > irq14: ata0 85 0 > irq16: vgapci0 5377 52 > irq21: hdac0 ohci0 742 7 > irq22: nfe0 ehci0 23610 229 > irq23: atapci1 5405 52 > cpu0: timer 203959 1980 > cpu1: timer 200914 1950 > Total 440325 4275 > interrupt total rate > irq1: atkbd0 234 2 > irq14: ata0 85 0 > irq16: vgapci0 5439 52 > irq21: hdac0 ohci0 742 7 > irq22: nfe0 ehci0 24621 236 > irq23: atapci1 5405 51 > cpu0: timer 205981 1980 > cpu1: timer 202937 1951 > Total 445444 4283 > > >I think the reduced performance can be explained by a clamp on the > > interrupt rate around 1000 interrupts per second instead of 8000. Maybe > > someone has an explanation for this? > > You right, the interrupt rate around 1000 (1011) on this machine, but on > FreeBSD 7.1 more 3000. If it is some kind of interrupt aggregation, may be > I can try to turn it off? > > >b) On the machine where it is fast. > > vmstat -i ; sleep 1 ; vmstat -i > interrupt total rate > irq4: uart0 4154 0 > irq14: ata0 472922 0 > irq15: ata1 26 0 > irq18: em0 752711 0 > irq21: ahc0 53 0 > irq23: ehci0 103456 0 > irq24: em1 147 0 > cpu0: timer 1551216517 2000 > cpu1: timer 1551195251 2000 > Total 3103745237 4001 > interrupt total rate > irq4: uart0 4154 0 > irq14: ata0 472923 0 > irq15: ata1 26 0 > irq18: em0 752713 0 > irq21: ahc0 53 0 > irq23: ehci0 110949 0 > irq24: em1 147 0 > cpu0: timer 1551218551 2000 > cpu1: timer 1551197285 2000 > Total 3103756801 4001Received on Wed Mar 04 2009 - 07:40:12 UTC
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