Messages in this thread | | | Date | Thu, 18 Apr 2002 18:54:02 -0700 | From | "Martin J. Bligh" <> | Subject | Re: page_alloc.c comments patch v2 |
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> I got confused when I was examining the code and got mixed up. I see now > the question about more that one ZONE_NORMAL in this pgdata_t is off, but > the query still (sortof) holds. Let me try again. > > I am an allocator and I start in HIGHMEM which has a pages_low value of 10 > (arbitary number). I find I would hit it if I allocated from there so I > move to NORMAL which also has a pages_low of 10 but now I am making sure I > am at least 20 pages are free in the NORMAL zone, not 10 and possibly > (presuming pages_low in DMA is 10) making sure 30 are free in DMA. Is this > the way things are meant to happen?
Ah, OK, I see what you were getting at now ;-)
It's hard to really tell what was intended - Andrea might be able to give you a better idea. However, from the way I read the code, it might seem to make more sense if the "min = 1UL << order;" was inside the loop rather than outside. That'd simply make sure we always left "zone->pages_low" free inside that zone .... if course it would make no sense to assign min and then increment it with += inside the loop, or even set it any more .... just
if (z->free_pages > z->pages_low + (1UL << order))
But all that's purely speculation, he might have meant it as it is ;-)
M.
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