On Fri, 14 Jul 2000, Rik van Riel wrote:
>Which is too late. That will lead to the typical
>"DMA buffer allocation failed" error message and
>the user will come to us complaining that the sound
>card no longer works after applying the VM patch.
Woops I was wrong when I said classzone doesn't balance the ZONE_DMA ;),
you was right, I was condraddicting myself (so there's not the problem you
mentioned above with classzone, but unfortunately classzone doesn't fix
the wastage of the atomic memory in case somebody won't use the ZONE_DMA
and we can't fix that at all because we must provide memory for atomic
allocations). So my whole point was flawed, sorry. So we'll waste more
memory and resources than 2.[02].x in case nobody will use the ZONE_DMA
but for a good reason that is to provide memory to atomic allocations.
Good, no point against that anymore.
However the zone_t is anyway necessary to optimize the memory balancing,
thanks to it when somebody asks for a __GFP_DMA allocation and he have to
block freeing memory himself, he will _never_ free a non DMA page by
mistake (so it will do the miniumum work necessary for allowing the
current allocation to succeed, if other work is necessary too it will be
done by kswapd in background since it's not necessary at the moment). This
is not done with 2.4.x and you may end balancing the ZONE_NORMAL even if
somebody asked for a DMA page because you miss the zone_t information. Is
this right or I'm still missing something?
Andrea
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This archive was generated by hypermail 2b29 : Sat Jul 15 2000 - 21:00:21 EST