Date: Mon, 05 Nov 2012 09:40:28 +0000 From: Joe Holden <lists@rewt.org.uk> To: Davide Italiano <davide@freebsd.org> Cc: current@freebsd.org Subject: Re: Dynamic Ticks/HZ Message-ID: <5097898C.9080109@rewt.org.uk> In-Reply-To: <CACYV=-Ef5ij7%2BgqDV9oS3xRyD6Yy2mqDyKqqUZZQ-KsWb_3C3A@mail.gmail.com> References: <509758B8.1000409@rewt.org.uk> <CACYV=-HwJ1j2-zDtCtuGNKzdFRJhPsZm6vtFXAVyPSabCXvFEQ@mail.gmail.com> <50975F6F.6010907@rewt.org.uk> <CACYV=-Ef5ij7%2BgqDV9oS3xRyD6Yy2mqDyKqqUZZQ-KsWb_3C3A@mail.gmail.com>
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Davide Italiano wrote: > On Nov 4, 2012 10:40 PM, "Joe Holden" <lists@rewt.org.uk> wrote: >> Davide Italiano wrote: >>> On Mon, Nov 5, 2012 at 7:12 AM, Joe Holden <lists@rewt.org.uk> wrote: >>>> Hi guys, >>>> >>>> Has some default changed between 9.1-RC2 and HEAD? >>>> >>>> On identical machines, one with 9.1-RC2 and one with HEAD from yesterday >>>> (GENERIC) I see the following in systat -v: >>>> >>>> 9.1: >>>> 65 cpu0:timer >>>> 10 cpu1:timer >>>> >>>> HEAD: >>>> 1127 cpu0:timer >>>> 22 cpu1:timer >>>> >>>> These are Supermicro i3 boxes and as far as I can see they have matching >>>> BIOS config. >>>> >>>> Thanks, >>>> J >>>> _______________________________________________ >>>> freebsd-current@freebsd.org mailing list >>>> http://lists.freebsd.org/mailman/listinfo/freebsd-current >>>> To unsubscribe, send any mail to " > freebsd-current-unsubscribe@freebsd.org" >>> >>> Which is your refresh rate for systat? >>> I generally measure sampling every one second (i.e. systat -vm 1). >>> Also, are you making your measurements when the system is idle? >>> In order to trace the source(s) of these interrupts you might consider >>> to collect data via KTR. >>> >> I'm also using a one second refresh rate, the system is entirely idle and > the interupt rate is almost entirely static at 1127, occasionally it will > drop to 1119. >> From what I understand the timer is hz/ticks which became dynamic in 9.0, > although that behaviour doesn't appear to be in HEAD anymore, at least on > this hardware. >> Thanks, >> J > > It should be available, AFAIK. As I can see from your previous post you get > about 20 interrupts on cpu1. This number is about 1/100 of the value you > get on a !tickless kernel. > If you provide the required ktr infos, probably someone will take a look. doh, running kernel wasn't as GENERIC as I thought it was, looks like device polling not only breaks dynamic ticks but also reduces rx ability significantly, exactly 150,000 pps per 1000hz on igb versus 650,000 without Is this a known issue? (and if device polling isn't as useful as it once was, should it be removed?)
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