From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Re: netif_rx packet dumping Date: Tue, 08 Mar 2005 10:27:17 -0800 Message-ID: <422DEE85.5010302@candelatech.com> References: <20050303123811.4d934249@dxpl.pdx.osdl.net> <42278122.6000000@ev-en.org> <20050303133659.0d224e61.davem@davemloft.net> <42278554.2090902@ev-en.org> <20050303135718.2e1a0170.davem@davemloft.net> <422DC7CE.2040800@ev-en.org> <20050308100902.24b67b2f.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: Andi Kleen , baruch@ev-en.org, shemminger@osdl.org, netdev@oss.sgi.com To: "David S. Miller" In-Reply-To: <20050308100902.24b67b2f.davem@davemloft.net> Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org David S. Miller wrote: > On Tue, 08 Mar 2005 18:00:49 +0100 > Andi Kleen wrote: > > >>Baruch Even writes: >> >>>I can squeeze the tcp_skb_cb to one pointer at the expense of extra >>>work to remove a packet from the list (the other pointer is the prev >>>pointer). >> >>You could also use a xor list in theory. But I'm not sure it's worth it. >>Increasing cb by 4 bytes shouldn't be a very big issue. > > > Going from "40" to "44" takes 64-bit platforms onto another cache line > for struct sk_buff, as I stated in another email. Seems like we might could squish the sk_buff a bit: Do we really need 32-bits for the mac-len: unsigned int len, data_len, mac_len, csum; Some of these flags could be collapsed into a single field and we could do bit-shift operations for the single flags we care about. This would also make it easier to add new flags as desired w/out growing the structure. unsigned char local_df, cloned, pkt_type, ip_summed; The priority could probably be 16 bits as well, do we really need more than 65k different priorities: __u32 priority; Of course...this might be things for 2.7 since lots of modules will probably be accessing these fields. Maybe to get started we could add macros to grab the flags and such so that when we finally do collapse things into a single flags field the external code doesn't have to know or care? Thanks, Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com