On Fri, Apr 29, 2011 at 10:01 AM, Chris Mason <chris.ma...@oracle.com> wrote: > Excerpts from John Wyzer's message of 2011-04-29 10:46:08 -0400: >> Currently on >> commit 7cf96da3ec7ca225acf4f284b0e904a1f5f98821 >> Author: Tsutomu Itoh <t-i...@jp.fujitsu.com> >> Date: Mon Apr 25 19:43:53 2011 -0400 >> Btrfs: cleanup error handling in inode.c >> >> merged into 2.6.38.4 >> >> I'm on a btrfs filesystem that has been used for some time. Let's say nine >> months. Very recently I noticed performance getting worse and worse. >> Most of the time it feels as if the system is just busy with iowait. >> Write and read performance during random access is mostly around 2MB/s, >> sometimes 1MB/s or slower. It's better for big files which can be read with >> about >> 6-9MB/s. The disk is a reasonably recent SATA disk (WDC_WD3200BEVT) so 30MB/s >> or 40MB/s linear reading should not be a problem. >> >> rootfs 291G 242G 35G 88% / >> >> I tried btrfs filesystem defragment -v / but did not notice any improvement >> after that. >> >> Is this a known phenomenon? :-) >> > > Sounds like you're hitting fragmentation, which we can confirm with > latencytop. Please run latencytop while you're seeing poor performance > and take a look at where you're spending most of your time. > > -chris > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
Also, please note that 'btrfs filesystem defragment -v /' will defragment the directory structure, but not the files. See: https://btrfs.wiki.kernel.org/index.php/Problem_FAQ#Defragmenting_a_directory_doesn.27t_work To defragment your entire volume, you'll need a command like: # for file in $(find <PATH/TO/BTRFS/VOL/> -type f); do btrfs filesystem defragment ${file}; done There's also a similar command in the FAQ referenced above. If you just want to see your fragmentation you can use the 'filefrag' program from e2fsprogs: # for file in $(find <PATH/TO/BTRFS/VOL/> -type f); do filefrag ${file}; done | sort -n -k 2 | less -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
