Wolfgang Denk <w...@denx.de> wrote on 03/11/2009 17:02:27: > > Dear Joakim Tjernlund, > > In message <1257263550-21504-1-git-send-email-joakim.tjernl...@transmode.se> > you wrote: > > Ported over the more efficient linux crc32() function. > > A quick comparsion on ppc: > > After changing the old crc32 to do 4 bytes in the > > inner loop to be able to compare with new version one can note: > > - old inner loop has 61 insn, new has 19 insn. > > - new crc32 does one 32 bit load of data to crc while > > the old does four 8 bits loads. > > - size is bit bigger for the new crc32: > > 1392(old) 1428(new) of text. Can probably be shrunk > > somewhat by inlining crc32(). > > The Purpose of Computing is Insight, Not Numbers. > > So how much faster does the new code run, on a real machine? How much > time can be saved to mount a real JFFS2 file system, or to checksum a > reall image file?
Picky I see. Like I said, numbers was done long time ago and isn't available now, the effects on mount time in linux was real. The best I am prepared to do is this(on mpc832x): New => date;crc 0 0xfffffff;date Date: 2009-11-03 (Tuesday) Time: 17:00:55 CRC32 for 00000000 ... 0ffffffe ==> b2474c51 Date: 2009-11-03 (Tuesday) Time: 17:01:34 -> 39 secs Old => date;crc 0 0xfffffff;date Date: 2009-11-03 (Tuesday) Time: 17:03:24 CRC32 for 00000000 ... 0ffffffe ==> 218bdca9 Date: 2009-11-03 (Tuesday) Time: 17:04:24 -> 60 secs If this isn't enough, you can always hope someone else wants to do further testing. Jocke _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
