From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3CD8BCF7.1090102@embeddededge.com> Date: Wed, 08 May 2002 01:51:51 -0400 From: Dan Malek MIME-Version: 1.0 To: acurtis@onz.com Cc: linuxppc-dev@lists.linuxppc.org Subject: Re: 8260 and skb implementation References: Content-Type: text/plain; charset=us-ascii; format=flowed Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: Allen Curtis wrote: > If you have another 60X bus master, ..... Ah, right, now I remember. > I do not know how to help you with hardware. I thought that the EST or > Tundra eval cards had local RAM. I had one of the original EST boards long ago. When trying to use the local RAM it would hang the CPM. There are remnants of code in the FCC driver that if enabled would keep the CPM buffer descriptors and things in the local RAM. > ... Do you believe moving SKB to local RAM has merit? I wouldn't make any decisions without some benchmarks, but I suspect CPM intensive access is more likely to benefit from using the local RAM. Things like buffer descriptors and ATM control information will likely win, I don't think SK bufs will because of the high processor core access. > ... Any oppinion > about the impact on the zero-copy implementation? We should make the change to the receive side so this happens. The transmit doesn't copy. I just copied the code from the 8xx long ago and never made the change. We can't properly do zero copy receive on processors that don't have coherent caches due to alignment and other information potentially shared in a cache line. Thanks. -- Dan ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/