I played around with the btrfs discard support now that I''ve finished trying up the ATA TRIM support to the block layer. These numbers are with an OCZ-Vertex SSD with the 1.4 firmware, on a 2.6.32-rc7 kernel and current git btrfs-progs with my patch do discard the whole device at mkfs time. I used this little script (with the discard option comment out for the non-discard run): ---- snip ---- #!/bin/sh OPTSOPTS="-o discard" ./mkfs.btrfs /dev/sdb mount -t btrfs $OPTS /dev/sdb /mnt/ cp -a ../linux-2.6 /mnt/ echo 1 > /proc/sys/vm/drop_caches time rm -rf /mnt/linux-2.6 time sync umount /mnt/ ---- snip ---- And here are the numbers: ---- snip ---- rm -rf sync With TRIM: real 0m19.375s real 0m8.603s user 0m0.065s user 0m0.000s sys 0m11.122s sys 0m0.070s real 0m16.267s real 0m8.277s user 0m0.049s user 0m0.001s sys 0m11.175s sys 0m0.117s real 0m16.039s real 0m9.883s user 0m0.058s user 0m0.000s sys 0m10.993s sys 0m0.157s real 0m16.277s real 0m8.419s user 0m0.057s user 0m0.000s sys 0m11.196s sys 0m0.161s real 0m16.264s real 0m9.017s user 0m0.063s user 0m0.000s sys 0m11.066s sys 0m0.152s Without: real 0m15.796s real 0m0.181s user 0m0.043s user 0m0.000s sys 0m10.950s sys 0m0.133s real 0m15.591s real 0m0.190s user 0m0.067s user 0m0.000s sys 0m11.157s sys 0m0.114s real 0m15.877s real 0m0.230s user 0m0.064s user 0m0.000s sys 0m11.162s sys 0m0.115s real 0m15.171s real 0m0.187s user 0m0.051s user 0m0.000s sys 0m11.156s sys 0m0.120s real 0m15.965s real 0m0.194s user 0m0.049s user 0m0.000s sys 0m11.327s sys 0m0.134s -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html