Messages in this thread | | | Date | Thu, 25 Sep 2003 18:12:58 -0700 | From | "David S. Miller" <> | Subject | Re: NS83820 2.6.0-test5 driver seems unstable on IA64 |
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On Thu, 25 Sep 2003 20:11:27 +0400 Ivan Kokshaysky <ink@jurassic.park.msu.ru> wrote:
> On Alpha it is - I did some experimentation yesterday with > the tulip driver and "rx_copybreak=0" vs default "rx_copybreak=1518". > 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.
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