Date: Wed, 1 Jun 2011 20:00:25 +0000 (UTC) From: Robert Watson <rwatson@FreeBSD.org> To: cvs-src-old@freebsd.org Subject: cvs commit: src/sys/net if_ethersubr.c Message-ID: <201106012000.p51K0Y4X058331@repoman.freebsd.org>
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rwatson 2011-06-01 20:00:25 UTC FreeBSD src repository Modified files: sys/net if_ethersubr.c Log: SVN rev 222583 on 2011-06-01 20:00:25Z by rwatson Add an optional netisr dispatch point at ether_input(), but set the default dispatch method to NETISR_DISPATCH_DIRECT in order to force direct dispatch. This adds a fairly negligble overhead without changing default behavior, but in the future will allow deferred or hybrid dispatch to other worker threads before link layer processing has taken place. For example, this could allow redistribution using RSS hashes without ethernet header cache line hits, if the NIC was unable to adequately implement load balancing to too small a number of input queues -- perhaps due to hard queueset counts of 1, 3, or 8, but in a modern system with 16-128 threads. This can happen on highly threaded systems, where you want want an ithread per core, redistributing work to other queues, but also on virtualised systems where hardware hashing is (or is not) available, but only a single queue has been directed to one VCPU on a VM. Note: this adds a previously non-present assertion about the equivalence of the ifnet from which the packet is received, and the ifnet stamped in the mbuf header. I believe this assertion to generally be true, but we'll find out soon -- if it's not, we might have to add additional overhead in some cases to add an m_tag with the originating ifnet pointer stored in it. Reviewed by: bz MFC after: 3 weeks Sponsored by: Juniper Networks, Inc. Revision Changes Path 1.283 +41 -1 src/sys/net/if_ethersubr.c
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