Re: [PATCH 5/5] processor: jiffies-based bm_check

[Dominik Brodowski <linux-X3ehHDuj6sIIGcDfoQAp7BvVK+yQ3ZXh@public.gmane.org>]

On Thu, Jan 20, 2005 at 11:08:06PM -0500, Len Brown wrote:
> On Thu, 2004-12-23 at 15:11, Len Brown wrote:
> 
> > Didn't apply the jiffies part yet.
> 
> I've applied it now. (attached as jiffy.patch)
> 
> However, "threshold.bm = 0xF" was written when
> HZ = 100 yielding 40ms, but this
> becomes 4ms for HZ = 1000.
> 
> While I don't know what the optimal value is for
> the bus master history threshold, it seemed like
> a good idea for it to default to about 40ms per
> the original code until we know better.
> 
> So I've also applied the attached bm_history.patch
> to default this to 0xFFFFFFFF for HZ = 1000 (32ms)
> and it is tunable via /sys/module/processor/parameters/bm_history
> 
> what do you think?

This sounds sensible to do. Note that the "diff" measured in idle() will
become problematic once "tickless" systems are implemented -- we'll sleep
for multiple jiffies then, and there was _no_ bm activiy in between. We need
to sort that out somehow...

	Dominik


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