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TMPFS is now in -Current tree under /src/sys/fs/tmpfs.
Porting TMPFS
TmpFS is 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@nokia.com ) and XinLi are working on it to continue this effort.
Todo List
- 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 sucessful.
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.