On 02/22/2013 02:16 AM, Timothy Coalson wrote: > The first parity uses straight XOR on uint64_t, while the second parity > performs the LFSR on all bytes in a uint64_t with some bitwise math (search > for VDEV_RAIDZ_64MUL_2) that adds up to 8 operators by my count, followed > by xor - using the LFSR lookup table on each byte might have a chance at > being faster, but its hard to know without testing. I am not at all > surprised it takes significantly more cpu time, and I see no way to make it > significantly closer in speed to a simple XOR.
I just tested by replacing some copy-loops with memcpy and restructuring some conditionals and got some appreciable speed gains. I wouldn't want to jump the gun yet, though. > However, the test indicated more than 1GB/s, is the N40L's processor really > 10x slower per core than the machine you ran the test on? I mean, sure, > its from 2010 and running at 1.5GHz, but still... I probably forgot to mention that these tests were conducted on an Athlon II Neo N36L @ 1.3GHz - pretty close to the N40L. Cheers, -- Saso _______________________________________________ OpenIndiana-discuss mailing list [email protected] http://openindiana.org/mailman/listinfo/openindiana-discuss
