On Sat, 2014-09-20 at 22:44 +0400, Maxim V FIlimonov wrote: > Hello everyone, > > Recently, I encountered a problem with -CURRENT on an ARM board (cubieboard2 > to be precise). The problem was that the load average was above 2. Including > the fact that the board has 2 CPU cores, that's strange. Also, the network > throughput was way too slow: from 3 kilobytes per second earlier to 20..50 > about now. > > Here's a workaround for that: > > sysctl kern.eventtimer.periodic=1 > With that, the network performance increased while LA decreased to a decent > 0.3..0.5.
Since it's happening only on that hardware, there's a good chance the problem is in the allwinner a10/a20 clock driver, not in the general eventtimer code. In fact, looking at the code it appears that a divide-by-16 is being set in the hardware, but not accounted for when setting the frequency of the eventtimer. Hmm, it should affect the timecounter too, in which case you'd see time-of-day advancing 16x too fast. If ntpd is running it would need to step the clock pretty frequently, which would show up in syslog. I don't have hardware to test on, please see if the attached patch makes a difference. -- Ian
Index: sys/arm/allwinner/timer.c =================================================================== --- sys/arm/allwinner/timer.c (revision 271909) +++ sys/arm/allwinner/timer.c (working copy) @@ -199,7 +199,7 @@ a10_timer_attach(device_t dev) val |= TIMER_ENABLE; timer_write_4(sc, SW_TIMER_IRQ_EN_REG, val); - sc->timer0_freq = SYS_TIMER_CLKSRC; + sc->timer0_freq = SYS_TIMER_CLKSRC / 16; /* Set desired frequency in event timer and timecounter */ sc->et.et_frequency = sc->timer0_freq;
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