From mboxrd@z Thu Jan 1 00:00:00 1970 From: "David S. Miller" Date: Fri, 26 Sep 2003 01:12:58 +0000 Subject: Re: NS83820 2.6.0-test5 driver seems unstable on IA64 Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org On Thu, 25 Sep 2003 20:11:27 +0400 Ivan Kokshaysky wrote: > On Alpha it is - I did some experimentation yesterday with > the tulip driver and "rx_copybreak=0" vs default "rx_copybreak18". > That's true, copying the large packet is very expensive due to constant > cache misses. On UP1500 it costs more than 2500 cycles per 1.5Kb > copy on large ftp transfers. > OTOH, minimal time to handle unaligned load is ~200 cycles (ev6 cpu), > but only when the trap handler itself and its data are in L1 cache > (like doing unaligned load in a tight loop). In the real life average > time is ~400 cycles due to cache misses. > Further, with "rx_copybreak=0" I've got 20 (!) unaligned traps per TCP > packet, i.e. penalty was 8000 vs 2500 cycles... Fine, then we should have something like an rx_copybreak scheme in the ns83820 driver too. Thanks for your data.