Re: ZONE_PADDING wastes 4 bytes of the new cacheline

Nick Piggin
2004-10-22T03:41:40Z

Andrew Morton wrote:
> Nick Piggin <nickpiggin@yahoo.com.au> wrote:
>
>>Andrew Morton wrote:
>>

>>I think they probably should be turned on. A system with a gig of ram
>>shouldn't be able to use up all of ZONE_DMA on pagecache. It seems like
>>a small price to pay... same goes for very big highmem systems and ZONE_NORMAL.
>
>
> Problem is, how much lower zone memory do you reserve? If someone is
> really getting hit by this in real life then the answer for their workload
> is probably "lots". If they are not getting hit then the answer is "none".
>

Yeah you might be right... although the ZONE_NORMAL can still be used
for other things like slab caches.

> Any halfway setting will screw everyone.
>
>

I guess what we really need to do is find someone who is getting hit by it.
Andrea do you have any pointers?