Date: Sat, 15 Dec 2012 13:42:07 +0200 From: Alexander Motin <mav@FreeBSD.org> To: Bruce Evans <brde@optusnet.com.au> Cc: svn-src-projects@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r244249 - projects/calloutng/sys/dev/syscons Message-ID: <50CC620F.9040005@FreeBSD.org> In-Reply-To: <20121215222500.Q2309@besplex.bde.org> References: <201212151044.qBFAiG70038633@svn.freebsd.org> <20121215222500.Q2309@besplex.bde.org>
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On 15.12.2012 13:33, Bruce Evans wrote:
> On Sat, 15 Dec 2012, Alexander Motin wrote:
>
>> Log:
>> Switch syscons from timeout() to callout_reset_flags() and specify that
>> precision is not important there -- anything from 20 to 30Hz will be
>> fine.
>
> 20-30 is still a lot. It could use adaptive timeouts of many seconds
> when there is no i/o, except for the blinking cursor. OTOH, precision
> might be important for the blinking cursor -- it would probably be
> even more distracting if it has uneven timing.
Yes, that's true. I just don't know syscons internals to do it. Somebody
is welcome to do it, as syscons now is the main source of time events.
>> Modified: projects/calloutng/sys/dev/syscons/syscons.c
>> ==============================================================================
>>
>> --- projects/calloutng/sys/dev/syscons/syscons.c Sat Dec 15
>> 10:30:06 2012 (r244248)
>> +++ projects/calloutng/sys/dev/syscons/syscons.c Sat Dec 15
>> 10:44:16 2012 (r244249)
>> ...
>> @@ -1831,7 +1833,8 @@ scrn_timer(void *arg)
>> /* don't do anything when we are performing some I/O operations */
>> if (suspend_in_progress || sc->font_loading_in_progress) {
>> if (again)
>> - timeout(scrn_timer, sc, hz / 10);
>> + callout_reset_flags(&sc->ctimeout, hz / 15, scrn_timer, sc,
>> + C_PRELSET(0));
>> return;
>> }
>> s = spltty();
>
> Why reduce the timeout?
Respecting specified precision, it will be 7.5-15Hz. I just tried to
stay about original value. Also that seems to be a rare case and so not
really important.
>> ...
>> @@ -1899,7 +1903,8 @@ scrn_timer(void *arg)
>> #endif
>>
>> if (again)
>> - timeout(scrn_timer, sc, hz / 25);
>> + callout_reset_flags(&sc->ctimeout, hz / 30, scrn_timer, sc,
>> + C_PRELSET(1));
>> splx(s);
>> }
>
> Most syscons timeouts except this were hz / 10. Now they are hz / 15.
> I increase this one too to hz / 10 in some kernels, and have never noticed
> the difference. The update rate for a movie needs to be 100 or 200 Hz,
> but for some reason an update rate of just 10 Hz is enough for syscons.
> At least for me. I notice flicker at 60 Hz.
My laptops are running at 10Hz, but I don't know average user wishes, so
prefer to leave it as-is.
--
Alexander Motin
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