Date: Thu, 27 Jan 2011 14:01:25 +0000 From: Carsten Heesch <sysconfig@ossafe.org> To: Janne Snabb <snabb@epipe.com> Cc: freebsd-xen@freebsd.org, luke@hybrid-logic.co.uk Subject: Re: I have a problem with iSCSI on AMD64 Xen HVM Message-ID: <0F524D72-3752-47FD-9234-ED009009B0A0@ossafe.org> In-Reply-To: <alpine.BSF.2.00.1101260038310.20212@tiktik.epipe.com> References: <AANLkTink37iAtMeNZ5NEhgKwPFOgXOVr4epSFxp=7Kmr@mail.gmail.com> <AANLkTink=S9WxJCVT%2BAOaMjiLPLg9gtSwF1VwdzexFG%2B@mail.gmail.com> <alpine.BSF.2.00.1101251425320.20212@tiktik.epipe.com> <1295969742.3187.48.camel@pow> <alpine.BSF.2.00.1101260038310.20212@tiktik.epipe.com>
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>> int max =3D 24 /* MAX_SKB_FRAGS + (rx->status <=3D = RX_COPY_THRESHOLD) */; I've just recompiled XENHVM setting this for a quick test: > int max =3D MAX_SKB_FRAGS; Before, I was receiving said error message a lot; now it's gone. Also, = throughput has massively increased! My test setup was: 2x FreeBSD/amd64 8.2-RC2 (compiled about a week ago), XENHVM kernel. Both DomU's were running on the same physical machine (CentOS 5.5 x86_64 = with Xen 4.3.3 on Intel i7), their xn0 NICs are using the same bridge on = Dom0. I was able to trigger the error message on the receiving side by doing a = simple "scp test.bin <target>:/dev/null" from one DomU to the other. = Throughput dropped within seconds from ~40MB/sec below 2MB/sec. Now, with that change in place, throughput remains well above 50MB/sec! = (approximates actual disk read speed minus SSH compression/encryption = overhead)=20 Which would be the right value for max? This was obviously only a quick, = dirty test. I haven't got a clue either, where the max=3D5 came from, = but it doesn't seem to be a reasonable value. Cheers Carsten
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