Messages in this thread | | | Subject | Re: [PATCH] RFC: kills consistent_dma_mask | From | Jes Sorensen <> | Date | 19 Aug 2003 05:03:33 -0400 |
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>>>>> "Pete" == Pete Zaitcev <zaitcev@redhat.com> writes:
>> It isn't even implemented on most platforms - only x86_64 and ia64 >> have support for it, while on the remaining archs using it >> according to the docs (with non-default value) could mean Oops or >> something like that.
Pete> Before you go for that, I'd rather see you implementing the Pete> double/tripple calls in drivers, check for effects, THEN go for Pete> removal of the mask. If you cannot do it, plea SGI people to Pete> test it on SN-2 for you (or same for Intel Tiger box).
Hi Pete,
That would be totally messy. Having drivers do the accounting of what mask is currently set and have them switch back and forth depending on what type of allocation is currently being used would be a nightmare to debug.
Pete> The consistent mask looks a little distasteful to me, and I Pete> think it should not buy us performance because consistent Pete> allocations are not supposed to be fast. They are bad, but what Pete> you are doing is worse: you are trying to ruin the day of Pete> legitimate users. Please, be reasonable. Get SGI buy-in and Pete> come back.
The thing is that we really want to do 32-bit allocations for consistent allocations if we can in anyway do it since it means the card can do SAC for all access to control structures. However as you mention there are cases where this isn't possible and we will have to take the hit of DAC cycles.
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