lkml.org 
[lkml]   [2007]   [Aug]   [21]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
    /
    DateMon, 20 Aug 2007 23:45:23 -0700 (PDT)
    FromLinus Torvalds <>
    SubjectRe: [linux-usb-devel] [4/4] 2.6.23-rc3: known regressions
    
    On Mon, 20 Aug 2007, Arjan van de Ven wrote:
    
    > 
    > On Mon, 2007-08-20 at 23:26 -0700, Linus Torvalds wrote:
    > > 
    > > On Mon, 20 Aug 2007, Arjan van de Ven wrote:
    > > > 
    > > > untested patch to add this to cpufreq; this is probably a good idea in
    > > > general even if using the latency framework doesn't end up being used
    > > > for fixing this regression...
    > > > 
    > > > 
    > > > --- linux-2.6.23-rc2/drivers/cpufreq/cpufreq.c.org	2007-08-20 22:58:32.000000000 -0700
    > > > +++ linux-2.6.23-rc2/drivers/cpufreq/cpufreq.c	2007-08-20 23:02:21.000000000 -0700
    > > > @@ -1604,6 +1604,12 @@ static int __cpufreq_set_policy(struct c
    > > >  	if (ret)
    > > >  		goto error_out;
    > > > 
    > > > +
    > > > +	if (system_latency_constraint() < policy->cpuinfo.transition_latency) {
    > > 
    > > That looks broken. "system_latency_constraint()" is in us, but 
    > > transition_latency is in ns, afaik.
    > > 
    > > But adding a "/ 1000" to turn the ns into us, and it migth even work.
    > 
    > 
    > eh woops yes indeed.
    > Shows me for not testing; I'll do that tomorrow when I'm more awake
    
    Side note: I think we migth want to also have some way of telling the user 
    *why* we're not doing frequency changes. Maybe as simple as a rate-limited 
    printk() or something.
    
    Otherwise, we'll easily be in a situation where some poor sod ends up 
    running constantly at lowest frequency, and no way of even seeing why. 
    Which sounds like a debugging nightmare.
    
    If the kernel spits out the occasional warning about the latency 
    violation, at least we get notified about there being potential problems.
    
    		Linus
    -
    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: 2007-08-21 08:49    [from the cache]
    ©2003-2008