Readdir performance results

From Linux NFS

Contents 1 Graphical comparison of commands 2 Data 3 About the server 4 About the kernels / shortcodes

Graphical comparison of commands

• ls -f
• ls -lU
• ls -U
• rm -rf

Data

• Readdir NFSv3 No Readdir Plus
• Readdir NFSv3 With Readdir Plus
• Readdir NFSv4 No Readdir Plus
• Readdir NFSv4 With Readdir Plus

About the server

• Lenovo thinkpad T400
• 3GB Ram
• Intel(R) Core(TM)2 Duo CPU P8600 @ 2.40GHz
• Linux 2.6.37-ARCH
• x86_64
• Export: /nfs 192.168.122.0/255.255.255.0(rw,fsid=0,no_subtree_check,async,no_root_squash,crossmnt,nohide)

About the kernels / shortcodes

• Kernels were compiled off of the master branch of Linus' git tree (git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git)
• 2.6.36 Kernels (Checked out from the tag "v2.6.36")
  • 36: This kernel has not been modified at all. It was compiled right after checking out "v2.6.36"
  • 36NORC: This kernel has the readdir plus cap for large directories removed
• 2.6.38 Kernels (Checked out from the tag "v2.6.38")
  • 38: This kernel has not been modified at all. It was compiled right after checking out "v2.6.38"
  • 38RC: This kernel has re-added the readdir plus cap for large directories
  • 38NB: This kernel features a more selective readdir operation. It issues a readdir plus call, and if the extra attributes are used then it will keep issuing readdir plus calls. If the attributes go unused, it will switch over to using a readdir call. This kernel also features loop detection for readdir cookies, a problem that only hit very large directories.