Date: Mon, 22 Jan 2007 16:01:03 +0100 From: Andre Oppermann <andre@freebsd.org> To: John Baldwin <jhb@freebsd.org> Cc: cvs-src@freebsd.org, src-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/kern uipc_socket.c Message-ID: <45B4D1AF.9070101@freebsd.org> In-Reply-To: <200701121206.47308.jhb@freebsd.org> References: <200611021745.kA2HjSZC018731@repoman.freebsd.org> <200701121206.47308.jhb@freebsd.org>
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John Baldwin wrote: > On Thursday 02 November 2006 12:45, Andre Oppermann wrote: >> andre 2006-11-02 17:45:28 UTC >> >> FreeBSD src repository >> >> Modified files: >> sys/kern uipc_socket.c >> Log: >> Use the improved m_uiotombuf() function instead of home grown sosend_copyin() >> to do the userland to kernel copying in sosend_generic() and sosend_dgram(). >> >> sosend_copyin() is retained for ZERO_COPY_SOCKETS which are not yet supported >> by m_uiotombuf(). >> >> Benchmaring shows significant improvements (95% confidence): >> 66% less cpu (or 2.9 times better) with new sosend vs. old sosend (non-TSO) >> 65% less cpu (or 2.8 times better) with new sosend vs. old sosend (TSO) >> >> (Sender AMD Opteron 852 (2.6GHz) with em(4) PCI-X-133 interface and receiver >> DELL Poweredge SC1425 P-IV Xeon 3.2GHz with em(4) LOM connected back to back >> at 1000Base-TX full duplex.) >> >> Sponsored by: TCP/IP Optimization Fundraise 2005 >> MFC after: 3 month > > This breaks writes of 0 bytes (e.g. write(s, NULL, 0)) to sockets because > m_getm2(NULL, 0, ...) returns NULL and thus m_uiotombuf() returns NULL and > sosend_*() now return EFAULT. sosend_copyin() correctly handles this case > since it always allocates at least one mbuf. I'm not sure if m_uiotombuf() > is at fault or if something else is, so I'll let you fix it. This explains > the recent breakage of kcheckpass (KDE screen saver password checker) on > current, and possibly other things as well. Fix is committed. Thank you for tracking it down. > Also, you've introduced another regression in that if the m_get2m() fails it > should be returning ENOBUFS and not EFAULT to userland. The comments in > sosend_*() about 'EFAULT being the only possible error' are obviously > wrong. :) We're always calling with M_WAITOK because we're coming from userland and may sleep forever. -- Andre
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