Re: [PATCH]O14int

[Nick Piggin]

Con Kolivas wrote:

> On Mon, 11 Aug 2003 19:15, Nick Piggin wrote:
>
> > Con Kolivas wrote:
> >
> > > On Mon, 11 Aug 2003 15:44, Martin Schlemmer wrote:
> > >
> > > > On Sat, 2003-08-09 at 11:04, Con Kolivas wrote:
> > > >
> > > > > On Sat, 9 Aug 2003 01:49, Con Kolivas wrote:
> > > > >
> > > > > > More duck tape interactivity tweaks
> > > > > s/duck/duct
> > > > >
> > > > >
> > > > > > Wli pointed out an error in the nanosecond to jiffy conversion which
> > > > > > may have been causing too easy to migrate tasks on smp (? performance
> > > > > > change).
> > > > > Looks like I broke SMP build with this. Will fix soon; don't bother
> > > > > trying this on SMP yet.
> > > > Not to be nasty or such, but all these patches have taken
> > > > a very responsive HT box to one that have issues with multiple
> > > > make -j10's running and random jerkyness.
> > > A UP HT box you mean? That shouldn't be capable of running multiple make
> > > -j10s without some noticable effect. Apart from looking impressive, there
> > > is no point in having 30 cpu heavy things running with only 1 and a bit
> > > processor and the machine being smooth as silk; the cpu heavy things will
> > > just be unfairly starved in the interest of appearance (I can do that
> > > easily enough). Please give details if there is a specific issue you
> > > think I've broken or else I wont know about it.
> > Yeah make -j10s won't be without impact, but I think for a lot of
> > interactive stuff they don't need a lot of CPU, just to get it
> > in a timely manner. And Martin did say it had been responsive.
> > Sounds like in this case your changes are causing the interactive
> > stuff to get less CPU or higher scheduling latency?
>
> Sigh..,
>
> No, it sounds to me like things are expiring faster than on default. He didn't 
> say make -j10, it was multiple -j10s. This is one where you simply cannot let 
> the scheduler keep starving the make -j10s indefinitely for X; on a server or 
> multiuser box X will simply cause unfair starvation. I'm trying to find a 
> workaround for this without rewriting whole sections of the scheduler code, 
> but I'm just not sure I should be trying to optimise for a desktop that runs 
> loads >16 per cpu. (I'll keep trying though, but if there is no workaround 
> that remains fair it wont happen)

Yep, I did see the multiple j10s ;)
I wasn't aware that there was longer term starvation of gccs by X. I
thought the scheduler had always been quite good at evening up the
total CPU time used and a change you made had recently introduced a
latency or interactiveness problem.

But Martin didn't give a very detailed description of the problem,
and no I definitely don't think you should be aiming at fixing
his problem if it causes starvation or harms more common loads.


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