> On Tue, 17 Jul 2001, Marcelo Tosatti wrote:
> > >
> > > Do you have any really compelling reasons for adding the zone parameter to
> > > swap-out?
> > Avoid the page-faults and unecessary swap space allocation.
> In that case, what's the argument for not just replacing the zone
> parameter with
> /* If we have enough free pages in this zone, don't bother */
> if (page->zone->nrpages > page->zone->high)
Inactive shortage and free shortage are different things.
Think about the case where you have high inactive shortage and no free
shortage at all.
It is a valid and real case.
> which works without having a silly single-zone special case (think
> multiple small zones, all under pressure, and one large zone that hasn't
> seen pressure in ages).
There is no problem with such a case. (if that is what you mean)
* If we are doing a zone-specific scan, do not
* touch pages from zones which don't have a
if (zone && !zone_inactive_shortage(page->zone))
We will always do pte aging for zones which have an inactive shortage, if
doing zone specific scanning or not.
> A single-zone parameter just looks fundamentally broken.
The "zone" parameter passed to swap_out() means "don't unmap pte's mapping
to pages belonging to not-under-shortage zones". It can (and it should) be
replaced by a "zone_specific" parameter.
> How do you determine "which zone"? All allocations are really about
> zone _lists_, not single zones.
> This same test (maybe nicely abstraced with something like a
> "page_zone_pressure(page)" inline function) makes sense in pretty much all
> the scanning functions. We want to _age_ the pages in such zones, but we
> may not actually want to do anything further.
I haven't exactly understood what you mean here, but I suppose changing
"zone_t *zone" to "int zone_specific" paramater answers your question,
Or I'm missing something ?
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