On 2012-11-06 12:24, Dietmar Maurer wrote: >> On 2012-11-06 10:46, Dietmar Maurer wrote: >>>>> This obviously breaks vhost when using multiple cores. >>>> >>>> With "obviously" you mean you already have a clue why? >>>> >>>> I'll try to reproduce. >>> >>> No, sorry - just meant the performance regression is obvious (factor 20 to >> 40). >>> >> >> OK. Did you try to bisect over qemu-kvm as well? > > No (I thought that is the same code base?)
Already answered, though accidentally in private only: it is the same code base now, but qemu-kvm has a different history and may contain versions that didn't suffer from the issue. Meanwhile I quickly tried to reproduce but didn't succeed so far (>10GBit between host and guest with vhost=on and 2 guest cores). However, I finally realized that we are talking about a pretty special host kernel which I don't have around. I guess this is better dealt with by Red Hat folks. Specifically, they should know what features that kernel exposes and what it lacks. Jan
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