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Date: Tue, 5 Nov 2013 17:01:15 +0000 From: Zoltan Kiss <zoltan.kiss@...rix.com> To: Ian Campbell <Ian.Campbell@...rix.com> CC: <wei.liu2@...rix.com>, <xen-devel@...ts.xenproject.org>, <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>, <jonathan.davies@...rix.com> Subject: Re: [PATCH net-next RFC 0/5] xen-netback: TX grant mapping instead of copy On 01/11/13 19:00, Zoltan Kiss wrote: > >> Based on my investigations the packet get only copied if it is > delivered to > >>Dom0 stack, which is due to this patch: > >>https://lkml.org/lkml/2012/7/20/363 > >>That's a bit unfortunate, but as far as I know for the huge majority > this use > >>case is not too important. >> Likely to be true, but it would still be interesting to know how badly >> this use case suffers with this change, and any increase in CPU usage >> would be interesting to know about as well. > I can't find my numbers, but as far as I remember it wasn't > significantly worse than grant copy. I will check that again. I've measured it now: with my patch it was 5.2 Gbps, without it 5.4. Both cases iperf in Dom0 maxed out its CPU, mostly in soft interrupt context, based on top. Zoli -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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