Re: problems with e1000 and jumboframes

From: Evgeniy Polyakov
Date: Fri Aug 04 2006 - 02:13:34 EST

On Fri, Aug 04, 2006 at 03:59:37PM +1000, Herbert Xu (herbert@xxxxxxxxxxxxxxxxxxx) wrote:
> Chris Leech <chris.leech@xxxxxxxxx> wrote:
> >
> > We could try and only use page allocations for older e1000 devices,
> > putting headers and payload into skb->frags and copying the headers
> > out into the skb->data area as needed for processing. That would do
> > away with large allocations, but in Jesse's experiments calling
> > alloc_page() is slower than kmalloc(), so there can actually be a
> > performance hit from trying to use page allocations all the time.
> Interesting. Could you guys post figures on alloc_page speed vs. kmalloc?

They probalby measured kmalloc cache access, which only falls to
alloc_pages when cache is refilled, so it will be faster for some short
period of time, but in general (especially for such big-sized
allocations) it is essencially the same.

> Also, getting memory slower is better than not getting them at all :)


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Evgeniy Polyakov
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