Deal all, Now I got test the btrfs with discard option on MMC (implemented discard request). but I can''t test the iozone benchmark test program with I/O error. Of course I disabled the discard option. it works well. and discard handling is tested with VFAT well. So I think BTRFS discard request seems to broken. Test kernel is commit 7e27d6e778cd87b6f2415515d7127eba53fe5d02 Author: Linus Torvalds <torvalds@linux-foundation.org> Date: Fri Jun 11 19:14:04 2010 -0700 Linux 2.6.35-rc3 scenarios are below. Any clues? Thank you, Kyungmin Park # mkfs.btrfs /dev/mmcblk0p1 -L mmc WARNING! - Btrfs Btrfs v0.19 IS EXPERIMENTAL WARNING! - see btrfs.wiki.kernel.org before using fs created label mmc on /dev/mmcblk0p1 nodesize 4096 leafsize 4096 sectorsize 4096 size 7.40GB Btrfs Btrfs v0.19 # mount -t btrfs -o ssd,discard /dev/mmcblk0p1 /mnt/mmc [39310.465000] device label mmc devid 1 transid 7 /dev/mmcblk0p1 [39310.470000] btrfs: use ssd allocation scheme # iozone -A -s 10m -U /mnt/mmc -f /mnt/mmc/test -e Iozone: Performance Test of File I/O Version $Revision: 3.326 $ Compiled for 32 bit mode. Build: linux-arm Contributors:William Norcott, Don Capps, Isom Crawford, Kirby Collins Al Slater, Scott Rhine, Mike Wisner, Ken Goss Steve Landherr, Brad Smith, Mark Kelly, Dr. Alain CYR, Randy Dunlap, Mark Montague, Dan Million, Gavin Brebner, Jean-Marc Zucconi, Jeff Blomberg, Benny Halevy, Erik Habbinga, Kris Strecker, Walter Wong, Joshua Root. Run began: Thu Jan 1 10:55:35 1970 Auto Mode 2. This option is obsolete. Use -az -i0 -i1 File size set to 10240 KB Include fsync in write timing Command line used: iozone -A -s 10m -U /mnt/mmc -f /mnt/mmc/test -e Output is in Kbytes/sec Time Resolution = 0.000001 seconds. Processor cache size set to 1024 Kbytes. Processor cache line size set to 32 bytes. File stride size set to 17 * record size. KB reclen write rewrite read reread 10240 4 [39337.095000] device label mmc devid 1 transid 12 /dev/mmcblk0p1 [39337.100000] btree_readpage_end_io_hook: 4 callbacks suppressed [39337.105000] btrfs bad tree block start 0 29421568 [39337.110000] btrfs bad tree block start 0 29421568 [39337.115000] btrfs bad tree block start 0 29425664 [39337.120000] btrfs bad tree block start 0 29425664 [39337.125000] btrfs bad tree block start 0 29372416 [39337.130000] btrfs bad tree block start 0 29372416 [39337.135000] btrfs bad tree block start 0 29376512 [39337.140000] btrfs bad tree block start 0 29376512 [39337.145000] Btrfs detected SSD devices, enabling SSD mode [39337.150000] btrfs bad tree block start 0 29380608 [39337.155000] btrfs bad tree block start 0 29380608 [39338.880000] device label mmc devid 1 transid 17 /dev/mmcblk0p1 [39338.895000] Btrfs detected SSD devices, enabling SSD mode 7494 8721 [39340.830000] device label mmc devid 1 transid 21 /dev/mmcblk0p1 [39340.845000] Btrfs detected SSD devices, enabling SSD mode Error reading block 0 40200000 read: Input/output error # -- 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 vger.kernel.org/majordomo-info.html