Date: Sat, 22 Sep 2007 21:34:58 +0400 From: "Artem Kuchin" <matrix@itlegion.ru> To: <freebsd-stable@freebsd.org> Subject: device polling and weird timer interrupt count from vmstat Message-ID: <01ae01c7fd3e$e6ff28f0$0c00a8c0@Artem>
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I enabled device polling in the kernel, in nics and set HZ=1000. How, when i do omni2# vmstat -i i see interrupt total rate irq14: ata0 47 0 irq15: ata1 41 0 irq28: em0 2268 4 irq72: twe0 58380 120 cpu0: timer 965994 1995 cpu3: timer 1 0 cpu1: timer 1 0 cpu2: timer 965857 1995 Total 1992589 4116 (it is dual xeon with HT, HT disabled, that why cpu3 and cpu1 are zero). What i don't understand is why timer rate on each cpu is 1995? I have set it to 1000, not 1995 or 2000. I have seen it showing 2000 on another box. So 1) why not 1000? 2) if it is supposed to be doubled (why?) when why not 2000? 3) Is timer int really generated on each cpu? Am i really wasting cpu time on ~4000 ints per second? 4) does twe driver use polling? whay about twa? how to check it in the sources? -- Regards, Artem
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