====== TMPFS (Temporary Filesystem) ======

====== Introduction ======

%%TmpFS%% was first developed by Julio M. Merino Vidal for %%NetBSD%% as a %%SoC%% project: [[http://netbsd-soc.sourceforge.net/projects/tmpfs/|Efficient memory file-system]]. Rohit Jalan ported it from %%NetBSD%% to %%FreeBSD%%. Now HowardSu and Glen Leeder (<glen.leeder@nokia.com> ) and XinLi are working on it to continue this effort.

====== Using TMPFS ======

tmpfs is included in Release since 7-Release. A typical usage is use tmpfs as /tmp mount point.
  - Change the /tmp mount point in /etc/fstab to: **tmpfs  /tmp  tmpfs  rw,mode=777  0  0**
  - **umount /tmp**
  - **mount /tmp**

====== TODO ======

  * Refine and improve locking.
  * Support unionfs, tmpfs can be used as an upper filesystem.
  * Extra attribute support

====== Testing Status ======

===== Regression Testing =====

We port %%NetBSD%% regression test cases.

All tests successful.

===== POSIX Correctness Testing =====

All tests successful.
Files=184, Tests=3353, 823 wallclock secs (29.94 cusr + 368.38 csys = 398.31 CPU)

===== Stress Testing =====

Survive after fsstress -n 10000 -p 50. Tested under AMD64/i386.

Any pressure testing in SMP box are highly welcomed.

===== Buildworld testing =====

We successfully build world to a tmpfs in 4-CPU box with -j32.

===== fsx Testing =====

fsx(tools/regression/fsx) is a tool to test the correctness of a filesystem read/write. It tests read, write, truncate, mmapread, mmapwrite, hole/extend write.

We passed fsx testing now.

===== Performance Testing =====

The vacache code is removed. sf_buf is used for data I/O. The performance will depends on sf_buf implementation in different platform. In Amd64, sf_buf is zero copy however i386 is not. So you will notice a performance difference.

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{{tag>Stale}}