Date: Sun, 21 Jan 2018 22:57:20 +0000 From: Johannes Lundberg <johalun0@gmail.com> To: Ian Lepore <ian@freebsd.org> Cc: Hans Petter Selasky <hps@selasky.org>, freebsd-current <freebsd-current@freebsd.org> Subject: Re: Periodical interrupt storm when playing game with USB keyboard Message-ID: <CAECmPws07U1=KkqgrjHotjnbPhX53n2L9Jj36guLruTJ-wc%2BCw@mail.gmail.com> In-Reply-To: <1516569725.42536.99.camel@freebsd.org> References: <CAECmPwvDQBYw=mKJpZfUdKpXSC8GysZKSk0f9qaZEXCvy_QeMA@mail.gmail.com> <e2851846-0678-5cb9-0fce-e9cf49c41a2e@selasky.org> <CAECmPwvgMDBTUjhAERe4bKLgNYCim9bwdHw2JEL0RgTckMjSDw@mail.gmail.com> <CAECmPwtWr0t5_xLgg4NMxnjz317sqnfR9-ttH62szq4fwPdO=Q@mail.gmail.com> <64218617-98d2-0e6e-5872-e44106e61bf7@selasky.org> <1516569725.42536.99.camel@freebsd.org>
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On Sun, Jan 21, 2018 at 9:22 PM, Ian Lepore <ian@freebsd.org> wrote: > On Sun, 2018-01-21 at 22:07 +0100, Hans Petter Selasky wrote: > > On 01/21/18 21:45, Johannes Lundberg wrote: > > > > > > What does kern.eventtimer.periodic do? The sysctl description > > > wasn't > > > that elaborate... > > It turns off re-programming the timer every time there is a new > > callout > > with earlier completion time. > > > > --HPS > > Well, it does more than that. It makes the system run "the old way" > where there are periodic timer interrupts that happen whether they need > to or not (bad for power saving), and there's no way to schedule > anything to happen on intervals other than when the periodic ticks > occur (so if kern.hz = 1000 and you ask to sleep for a microsecond you > may actually sleep up to a millisecond). > > Thanks for the further explanation. I curious as to where the problem might be though.. It is the game's binary-only Linux executable (Unreal Engine 2.5), Linux SDL 1.2, or on the FreeBSD side? Haven't experienced anything similar with Quake3... Switching to periodic timer feels like overkill but it does the job as a work around. > -- Ian >
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