Date: Sun, 21 Jan 2007 23:35:06 +0300 From: Andrey Chernov <ache@FreeBSD.org> To: John Baldwin <jhb@FreeBSD.org> Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, Andre Oppermann <andre@FreeBSD.org>, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/kern uipc_socket.c Message-ID: <20070121203506.GA32483@nagual.pp.ru> In-Reply-To: <200701121206.47308.jhb@freebsd.org> References: <200611021745.kA2HjSZC018731@repoman.freebsd.org> <200701121206.47308.jhb@freebsd.org>
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On Fri, Jan 12, 2007 at 12:06:46PM -0500, 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. > > 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. :) Is there any progress in fixing this bug?
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