Subject: Re: [RFC] [PATCH 0/3] ioat: DMA engine support

From: Avi Kivity <[email-masked]>
Date: Thu, 24 Nov 2005 17:24:34 +0200

Andi Kleen wrote:

>>Don't forget that there are benefits of not polluting the cache with the 
>>traffic for the incoming skbs.
>>    
>>
>
>Is that a general benefit outside benchmarks? I would expect
>most real programs to actually do something with the data
>- and that usually involves needing it in cache.
>
>  
>
As an example, an NFS server reads some data pages using iSCSI and sends 
them using NFS/TCP (or vice versa).

>>In the I/O AT case it might make sense to do a few prefetch()es of the 
>>userland data on the return-to-userspace code path.  
>>    
>>
>
>Some prefetches for user space might be a good idea yes
>
>  
>
As long as they can be turned off. Not all usespace applications want to 
touch the data immediately.