Date: Wed, 15 Apr 2009 08:40:31 -0700 From: Renaud Lienhart <renaud@vmware.com> To: freebsd-net@freebsd.org Subject: tcp_output() might generate invalid TSO frames Message-ID: <20090415084031.6d149fef@renaud-dev1>
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Hi, We're having trouble virtualizing FreeBSD 7+ on ESX because of an issue with the stack's TSO implementation: it sometimes generates TSO packets whose payload size is actually smaller than the MSS. The faulty logic is described, along with a patch, in PR #132832. It has been opened for a while now, without any apparent activity, which is why I'm reaching the mailing list directly. ESX currently drops these packets as many physical nics are known to choke on such frames, which effectively limits FreeBSD guests' performance. I don't know about other virtualization stacks' behavior. http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/132832 Thanks for your time, Renaud
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