Date: Sat, 20 Sep 2014 17:46:09 -0600 From: Ian Lepore <ian@FreeBSD.org> To: Maxim V FIlimonov <che@bein.link> Cc: freebsd-arm <freebsd-arm@freebsd.org> Subject: Re: FreeBSD-11.0-CURRENT on ARM: performance and load average Message-ID: <1411256769.66615.155.camel@revolution.hippie.lan> In-Reply-To: <1989123.lKm0QJoZES@quad> References: <7351653.A2UeEk9AA3@quad> <1411241048.66615.148.camel@revolution.hippie.lan> <1989123.lKm0QJoZES@quad>
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On Sun, 2014-09-21 at 01:04 +0400, Maxim V FIlimonov wrote: > On Saturday 20 September 2014 13:24:08 Ian Lepore wrote: > > 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'm running FreeBSD-current on the board right now, the time is just fine. > > > I don't have hardware to test on, please see if the attached patch makes > > a difference. > > > > Well, it did: with the patch applied, the time ran about 60 times as fast as > it should have. I didn't notice any changes with load average, though: maybe > it's because I forgot to turn that sysctl setting I set before back to 0. > > wbr, Maxim Filimonov > che@bein.link 60 times as fast doesn't make much sense for changing a divisor to 16. Without that patch, what is the output of sysctl kern.eventtimer sysctl kern.timecounter If you repeatedly do "ntpdate -q <some server>" every 15 seconds for a couple minutes, does the offset stay pretty much the same? (like no big changes in the first two decimal places) Don't use a server like pool.ntp.org where you might get a different server every time, instead do "host pool.ntp.org" and pick one of the IPs and use it every time. -- Ian
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