From mboxrd@z Thu Jan 1 00:00:00 1970 Message-Id: <4.3.2.20001213174222.00bfdef0@falcon.si.com> Date: Wed, 13 Dec 2000 17:45:26 -0500 To: Brian Ford , Dan Malek From: Jerry Van Baren Subject: Re: 2.5 or 2.4 kernel profiling Cc: Graham Stoney , linuxppc-embedded@lists.linuxppc.org In-Reply-To: References: <3A37A048.46E692A0@mvista.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: At 04:08 PM 12/13/00 -0600, Brian Ford wrote: >On Wed, 13 Dec 2000, Dan Malek wrote: > > > Graham Stoney wrote: > > [snip] >I speak only for the 8260, but... > >With it, you can DMA directly into IP aligned skbuffs, eliminating the >copy. I've done it and it seems to work. I'll have to benchmark it, but >the copy overhead should be significant. This just makes IP do the >checksum later. > >Also, to avoid bus contention, shouldn't the Rx buffers be on the local >bus? Probably the BD's too. Unless we can figure out how to >put these in DPRAM, but it doesn't look possible for the FCC's. I don't >know if it is possible to allocate skbuffs in other than 60x bus SDRAM, >though. I asked the Mot help line about this. There response follows. The bottom line, according to them, is that you can put the BDs in DPRAM, but it will still cause 60x bus cycles, defeating the purpose of putting them in DPRAM. I have not personally verified this. ---------------------------------------------------------------------- Date: Wed, 3 May 2000 07:36:33 +0200 Subject: Motorola DigitalDNA Help, Service Request # 1-PUU6 Reply To: vanbaren_gerald@si.com From: DigitalDNA Help MIME-Version: 1.0 Reply-To: DigitalDNA Help Message-Id: <390FCC60.2280E779@tcfc.tornado.nsk.ru> Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii Content-Length: 2170 X-UID: 1 Dear K Van Baren, in reply to your Service Request SR 1-PUU6 [ref. TORLP] (see details below): CPM busy-polling adds about 1% overhead to bus activity. Can you ignore it? You may put FCC BDs in Dual-Port RAM but CPM will continues to access them through 60x bus. The only way to disable this polling is to emit STOP TX command when you have not data to send. ------- Details of your request: ------- Date Opened : 04 Apr 2000 06:46:09 Product : MPC8260 Category: Technical Request ---------- Subject ---------- 8260 FCC buffer description ---------- Description ---------- I want to minimize bus activity due to the CPM busy-polling buffer descriptors for the transmit "ready" flag. I realize I can turn off the polling and do the transmit on demand trick, but polling is convenient. To minimize bus activity, I wish to put the FCC buffer descriptors in Dual-Port RAM. The discussion of Dual-Port RAM in section 13.5 talks about the buffer descriptors residing in Dual-Port RAM or in main memory. The SCC discussion on buffer descriptors in section 19.2 says the buffer descriptors for the SCCs, SMCs, SPI, and I2C _must_ reside in Dual-Port RAM, and the RBASE and TBASE definitions enforce that since they are 16 bits only. The FCCs are not mentioned in the above list. The FCC parameter RAM has a full 32 bit address for RBASE and TBASE and there is a flag that selects whether the buffer descriptors are in local bus memory or 60x bus memory. Can they be put in Dual-Port RAM? ------- End of request details ------- To review or update this Service Request, or to enter a new Service Request, please access Motorola's Customer Support web site at http://www.motorola.com/semiconductors/support If there is ever an occasion when you cannot access Motorola's Customer Support web site, you can also contact us by sending an email to DigitalDNA.Help@motorola.com or by calling us at one of the following numbers: Americas 1-800-521-6274 7AM-6PM Phoenix Asia +852-2666-8307 8AM-6PM Hong Kong Japan 0120-191-014 8AM-5PM Tokyo Europe +49-89-92103-559 9AM-5PM Munich Regards, Motorola Semiconductors Customer Support ---------------------------------------------------------------------- [snip] >Opinions welcome. I have plenty of them :-) >-- >Brian Ford >Software Engineer >Vital Visual Simulation Systems >FlightSafety International >Phone: 314-551-8460 >Fax: 314-551-8444 gvb ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/