[ofa-general] Re: [PATCH/RFC] IPoIB: Allocate priv->tx_ring with vmalloc()

[Eli Cohen]

On Thu, 2008-03-13 at 12:04 +0200, Or Gerlitz wrote:
> Roland,
> 
> Just curious why you think extra pointer indirection for each send is 
> worse than TLB misses taken by using vmalloc(), are the latter being 
> excepted very un often? Also assuming keeping the dma addresses at the 
> TX descriptor is a practice taken also by Ethernet drivers who do have 
> big send queues, maybe we should look there to see how this problem was 
> solved?
> 
> Or.
> 
I think that a TLB miss will happen only once for each process while a
cache miss on the pointer might happen more often. The question is
whether it is significant or not. I think the biggest drawback of
vmalloc is the scarce space in 32 bit systems - other than that it is
preferred over kmalloc for each entry.