Date: Mon, 7 Dec 2015 10:09:42 -0500 (EST) From: Rick Macklem <rmacklem@uoguelph.ca> To: Alexander Kabaev <kabaev@gmail.com> Cc: FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: slow screen updates on laptop console (i386) Message-ID: <697195597.121770130.1449500982738.JavaMail.zimbra@uoguelph.ca> In-Reply-To: <20151207091815.16e11a13@kan> References: <900422043.121631608.1449496955386.JavaMail.zimbra@uoguelph.ca> <20151207091815.16e11a13@kan>
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Alexander Kabaev wrote:
> On Mon, 7 Dec 2015 09:02:35 -0500 (EST)
> Rick Macklem <rmacklem@uoguelph.ca> wrote:
>
> > Hi,
> >
> > When running FreeBSD-current on an old i386 laptop, the console
> > screen is intermittently slow to display output. The hesitations
> > can be several seconds.
> > Sometimes it shows up when I'm typing such that it takes seconds
> > for the characters to echo.
> > I think it is the display/output side, since I've seen it happen when
> > doing "more <file>", where the screen is stuck half way through
> > displaying the page for a few seconds.
> >
> > I don't see any problem when going into the machine remotely and
> > I don't see the problem on the other laptop I have running
> > FreeBSD/amd64.
> >
> > It has been happening for a while. It occurs on the oldest kernel
> > I have lying around (r287930, Sep. 17, 2015).
> >
> > I've tried the old "sc" driver and it seems to happen less with it,
> > but it still occurs.
> >
> > I'll admit I have no idea what drives doing output for the display
> > screen.
> >
> > Anyone have ideas w.r.t. this?
> >
> > Thanks in advance, rick
>
> Hi,
>
> maybe a stretch, but I would try selecting different eventtimer, if
> available. Say, I had to select HPET on my old i7 920 to make timeouts
> run reliably.
>
> sysctl kern.eventtimer.timer=HPET
>
Great guess! Actually this old laptop doesn't have HPET, but switching it
from LAPIC->RTC seems to have fixed the problem.
(I had a hunch it was something timer/interrupt related, but I don't know
that part of the system.)
--> Just fyi, my other laptop that works fine defaulted to HPET. It looks
like HPET rates higher than LAPIC.
Thanks a lot, rick
> --
> Alexander Kabaev
>
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