lkml.org 
[lkml]   [2007]   [Jan]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 11/23] clocksource: atomic signals

* Daniel Walker <dwalker@mvista.com> wrote:

> Modifies the way clocks are switched to in the timekeeping code. The
> original code would constantly monitor the clocksource list checking
> for newly added clocksources. I modified this by using atomic types to
> signal when a new clock is added. This allows the operation to be used
> only when it's needed.

I see little difference between your and John's code: both poll
something - you poll an atomic "did a new clocksource arrive" flag in
the timer interrupt, John takes the clocksource_lock spinlock and checks
a "did a new clocksource arrive" variable. Both are global atomic
variables in essence.

what i'd see as a real cleanup here would be to get away from this 'poll
whether there's any clocksource update' model, and to just ensure that a
running timer irq will always see the latest clocksource. I.e. to run
the change_clocksource() logic (and the following updates) when a new
clock source is selected - not when the next timer interrupt runs. That
would propagate all effects of a new clock source immediately.

Ingo
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-01-31 12:11    [W:0.183 / U:1.624 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site