I have been testing iops performance using different compression settings and found that setting either zero_buffers or buffer_compress_percentage was not enough, I had to also set scramble_buffers=0 in order to get the desired compression. But this was not the case when setting refill_buffers. I tested with fio 2.1.5 and fio from git (fio-2.1.6.1-10-g4e59d). My job file: [global] bs=4k ioengine=libaio iodepth=32 direct=1 size=8g time_based filename=/dev/sdf #scramble_buffers=0 #refill_buffers zero_buffers #buffer_compress_percentage=100 [rand-write-iops] rw=randwrite runtime=10 stonewall My results: scramble_buffers=0 buffer_compress_percentage=100 iops=83254 scramble_buffers=0 buffer_compress_percentage=0 iops=51137 scramble_buffers=1 buffer_compress_percentage=100 iops=69639 scramble_buffers=1 buffer_compress_percentage=0 iops=69429 ----- scramble_buffers=0 zero_buffers iops=83339 scramble_buffers=1 zero_buffers iops=69510 ----- scramble_buffers=0 refill_buffers iops=50774 scramble_buffers=1 refill_buffers iops=50813 -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
