TMPFS (Temporary Filesystem)

Introduction

TmpFS was first developed by Julio M. Merino Vidal for NetBSD as a SoC project: Efficient memory file-system. Rohit Jalan ported it from NetBSD to FreeBSD. Now HowardSu and Glen Leeder (<glen.leeder AT nokia DOT com> ) and XinLi are working on it to continue this effort.

Contents

  1. TMPFS (Temporary Filesystem)
  2. Introduction
  3. Using TMPFS
  4. TODO
  5. Testing Status
    1. Regression Testing
    2. POSIX Correctness Testing
    3. Stress Testing
    4. Buildworld testing
    5. fsx Testing
    6. Performance Testing

Using TMPFS

tmpfs is included in Release since 7-Release. A typical usage is use tmpfs as /tmp mount point.

  1. Change the /tmp mount point in /etc/fstab to:

    • tmpfs /tmp tmpfs rw,mode=777 0 0

  2. umount /tmp

  3. mount /tmp

TODO

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.

CategoryStale

TMPFS (last edited 2022-09-19T01:33:53+0000 by KubilayKocak)