27 Aug, 2013

1 commit

• ae77cbc1e   RAID: add tilegx SIMD implementation of raid6 ... Browse Code »

  This change adds TILE-Gx SIMD instructions to the software raid
  (md), modeling the Altivec implementation. This is only for Syndrome
  generation; there is more that could be done to improve recovery,
  as in the recent Intel SSE3 recovery implementation.

  The code unrolls 8 times; this turns out to be the best on tilegx
  hardware among the set 1, 2, 4, 8 or 16. The code reads one
  cache-line of data from each disk, stores P and Q then goes to the
  next cache-line.

  The test code in sys/linux/lib/raid6/test reports 2008 MB/s data
  read rate for syndrome generation using 18 disks (16 data and 2
  parity). It was 1512 MB/s before this SIMD optimizations. This is
  running on 1 core with all the data in cache.

  This is based on the paper The Mathematics of RAID-6.
  (http://kernel.org/pub/linux/kernel/people/hpa/raid6.pdf).

  Signed-off-by: Ken Steele
  Signed-off-by: Chris Metcalf
  Signed-off-by: NeilBrown

  Ken Steele

  2013-08-27 14:05:50 +0800