|| ||Jens Axboe <axboe-AT-suse.de>|
|| ||splice status|
|| ||Thu, 20 Apr 2006 16:29:03 +0200|
Since a lot of splice/tee stuff has been merged, I thought I'd post a
little status report and other potentially useful info.
- splice interfaces should be stable now, I don't envision any further
changes to the ->splice_read or ->splice_write file_operations hooks
or the splice syscall. splice now accepts an input or output offset
like sendfile(), so it doesn't have to rely on ->f_pos in the file
- Ditto for the sys_tee syscall.
- sendfile() will be replaced with splice(). sys_sendfile will remain of
course, this is only an internal thing. The current do_splice_direct()
is a sendfile() helper. The splice branch in the block git repo has
a patch to remove generic_file_sendfile() and all it's users by
converting them to ->splice_read(). There's also a patch there that
fixes up loop. The only remaining users of the file_operations
.sendfile hook are nfds/shmem/ext2-xip/relay. That still needs doing.
The current plan is to merge this stuff post 2.6.17.
I have a little collection of splice test tools that people may find
useful to play with this stuff. It's in a git repo here:
and snapshots are generated every hour on changes and can be fetched
There are tools there to test both splice and tee, a little README
explains the basic principle of them. I'd appreciate people testing and
playing with these tools, just in case we still have some bugs lurking.
Finally, known bugs:
- Some smallish splice reads are buggy. Patch is in splice branch and
will hopefully be merged whenever Linus gets in front of his computer.
- The ->splice_pipe cache needs to be initialized to NULL on forks. Only
affects do_splice_direct() usage, so not a problem in current kernels.
Patch also Linus bound today.
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