Date: Mon, 25 Sep 2017 11:10:48 +0000 From: "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net> To: "Stephen Hurd" <shurd@sasktel.net> Cc: "Stephen Hurd" <shurd@FreeBSD.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r323942 - head/sys/net Message-ID: <4523452E-79B0-494A-B44F-44DE4B747D69@lists.zabbadoz.net> In-Reply-To: <89d68ff8-84ed-83a6-4e77-9a321babe2fe@sasktel.net> References: <201709230135.v8N1ZE6S063264@repo.freebsd.org> <B28D9879-4ECF-43E4-9A58-51F616CEC4BE@lists.zabbadoz.net> <283397c7-a01e-3776-7ed3-b64d68003d0b@sasktel.net> <6F5DC92C-2CF6-4A33-9663-BFECB7DB65F2@lists.zabbadoz.net> <89d68ff8-84ed-83a6-4e77-9a321babe2fe@sasktel.net>
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On 23 Sep 2017, at 23:46, Stephen Hurd wrote: > Bjoern A. Zeeb wrote: >> On 23 Sep 2017, at 6:32, Stephen Hurd wrote: >> >>> Bjoern A. Zeeb wrote: >>>> On 23 Sep 2017, at 1:35, Stephen Hurd wrote: >>>> >>>>> Author: shurd >>>>> Date: Sat Sep 23 01:35:14 2017 >>>>> New Revision: 323942 >>>>> URL: https://svnweb.freebsd.org/changeset/base/323942 >>>>> >>>>> Log: >>>>> Chain mbufs before passing to if_input() >>>>> >>>>> Build a list of mbufs to pass to if_input() after LRO. Results >>>>> in >>>>> 12% small packet forwarding rate improvement. >>>> forwarding seems a confusing word here.. >>> >>> The test was small (64 byte frames) received on one interface, then >>> sent out on a different one using the net.inet.ip.forwarding sysctl >>> (controlled via the gateway_enable setting in rc.conf). >> >> Then this makes no sense as we don’t do LRO if forwarding is >> enabled on the machine; >> https://svnweb.freebsd.org/base/head/sys/netinet/tcp_lro.c?annotate=317390#l645 > > Basically, it changed from this: .. > To this: … > So while before it called if_input() for each separate mbuf that was > not LROed, it now builds a chain of mbufs that were not LROed, and > makes a single call to if_input() with the whole chain. For cases > like packet forwarding where no packets are LROed, performance is > better. Got it, so the “after LRO” in the original commit message is as confusing as forwarding. I not saying anything against the change, I am just saying the commit message doesn’t describe what it does. Also I am pretty sure this works with ether_input but not so much with fddi_input, iso88025_input, and ifdead_input is probably going to leak as well. /bz
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