Justin Piszcz wrote: > For these benchmarks I timed how long it takes to extract a standard 4.4 > GiB DVD: > > Settings: Software RAID 5 with the following settings (until I change > those too): > > Base setup: > blockdev --setra 65536 /dev/md3 > echo 16384 > /sys/block/md3/md/stripe_cache_size > echo "Disabling NCQ on all disks..." > for i in $DISKS > do > echo "Disabling NCQ on $i" > echo 1 > /sys/block/"$i"/device/queue_depth > done > > p34:~# grep : *chunk* |sort -n > 4-chunk.txt:0:45.31 > 8-chunk.txt:0:44.32 > 16-chunk.txt:0:41.02 > 32-chunk.txt:0:40.50 > 64-chunk.txt:0:40.88 > 128-chunk.txt:0:40.21 > 256-chunk.txt:0:40.14*** > 512-chunk.txt:0:40.35 > 1024-chunk.txt:0:41.11 > 2048-chunk.txt:0:43.89 > 4096-chunk.txt:0:47.34 > 8192-chunk.txt:0:57.86 > 16384-chunk.txt:1:09.39 > 32768-chunk.txt:1:26.61 > > It would appear a 256 KiB chunk-size is optimal. Can you retest with different max_sectors_kb on both md and sd? Also, can you retest using dd with different block-sizes? Thanks! -- Al - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
