Hi all, I have chosen to install bcache using the bcache-for-upstream branch (recompiled this morning for the latest patches). Even though everything is running smoothly, I am surprised by the very poor performance I'm obtaining from my setup. 1. Everything is setup on my laptop which has a 500GB HD (sda) and a 16 GB SSD (sdb). 2. I have setup an LVM above bcache, and /dev/sda4 is the only cache partition. The whole thing was setup with: make-bcache -B /dev/sda4 -C /dev/sdb the LVM is "inside" /dev/sda4 3. I am using fio as a benchmark, have setup writeback # cat /sys/block/bcache0/bcache/writeback_running 1 and I think I have followed every hints I could found about performance tuning. Yet, when running the ssd fio test suite on a file on partition that is not "cached", I am obtaining the following figures: seq-read: iops=29156 rand-read: iops=291 seq-write: iops=22355 rand-write: iops=260 Running it on a cached file system I'm obtaining: seq-read: iops=22196 rand-read: iops=330 seq-write: iops=15864 rand-write: iops=387 What am I missing ? The benchmark parameters are: bs=4k ioengine=libaio iodepth=64 size=1g direct=1 Thanks in advance for your answers, Leslie. -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
