From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [IPoIB] Identify multicast packets and fix IGMP breakage V3 Date: Thu, 26 Aug 2010 17:07:16 -0700 (PDT) Message-ID: <20100826.170716.68143372.davem@davemloft.net> References: <20100826234342.GA24333@obsidianresearch.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org, rdreier-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, ogerlitz-smomgflXvOZWk0Htik3J/w@public.gmane.org, yosefe-smomgflXvOZWk0Htik3J/w@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: cl-vYTEC60ixJUAvxtiuMwx3w@public.gmane.org Return-path: In-Reply-To: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org From: Christoph Lameter Date: Thu, 26 Aug 2010 18:57:09 -0500 (CDT) > On Thu, 26 Aug 2010, Jason Gunthorpe wrote: > >> I think doing the memcmp only in the multicast path should be >> reasonable overhead wise. > > Thats is not always possible. Here the multicast path is the > default path that is taken 99% of the time. The highest cost is bringing in that packet header's cache line, which you've already done by reading the byte and checking for 0xff. I doubt the memcmp() can possibly matter. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html