Date: Thu, 10 Apr 2003 17:25:48 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: RDB <rdb@blarg.net> Cc: freebsd-performance@freebsd.org Subject: Re: Semi-polling mode and net.inet.tcp.inflight_enable Message-ID: <3E960B8C.B33C8F57@mindspring.com> References: <Pine.LNX.4.44.0304101628510.14724-100000@win149.staff.flyingcroc.net>
next in thread | previous in thread | raw e-mail | index | archive | help
RDB wrote: > I'm curious whether anyone on this list has found real-world circumstances > in which either semi-polling mode or the net.inet.tcp.inflight_enable > setting improved performance, and if so what the circumstances were. Receiver livelock. However, it's not as good as full LRP. To see this, put a Gigabit card into a 32bit PCI @ 33MHz, and drive it full tilt from client machines. Watch as your data peaks, and then stops coming in at all, because all your mbufs are used up, and all your PCI bandwidth is being consumed by DMA's of incoming packets, and you have no cycles left over to do any work. Then go read the Jeffrey Mogul DECWRL paper from 1991, and be enlightened. -- Terry
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?3E960B8C.B33C8F57>