> -----Original Message-----
quoted text
> From: Andi Kleen [mailto:andi@firstfloor.org] 
> Sent: Wednesday, October 10, 2007 9:02 AM
> To: Waskiewicz Jr, Peter P
> Cc: David Miller; andi@firstfloor.org; hadi@cyberus.ca; 
> shemminger@linux-foundation.org; jeff@garzik.org; 
> johnpol@2ka.mipt.ru; herbert@gondor.apana.org.au; 
> gaagaan@gmail.com; Robert.Olsson@data.slu.se; 
> netdev@vger.kernel.org; rdreier@cisco.com; 
> mcarlson@broadcom.com; jagana@us.ibm.com; 
> general@lists.openfabrics.org; mchan@broadcom.com; 
> tgraf@suug.ch; randy.dunlap@oracle.com; sri@us.ibm.com; 
> kaber@trash.net
> Subject: Re: [ofa-general] Re: [PATCH 2/3][NET_BATCH] net 
> core use batching
> 
> > We've done similar testing with ixgbe to push maximum descriptor 
> > counts, and we lost performance very quickly in the same 
> range you're 
> > quoting on NIU.
> 
> Did you try it with WC writes to the ring or CLFLUSH?
> 
> -Andi

Hmm, I think it might be slightly different, but it still shows queue
depth vs. performance.  I was actually referring to how many descriptors
we can represent a packet with before it becomes a problem wrt
performance.  This morning I tried to actually push my ixgbe NIC hard
enough to come close to filling the ring with packets (384-byte
packets), and even on my 8-core Xeon I can't do it.  My system can't
generate enough I/O to fill the hardware queues before CPUs max out.

-PJ Waskiewicz
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