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| author | Dipankar Sarma <dipankar@in.ibm.com> | 2005-09-09 13:04:13 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-09-09 13:57:55 -0700 |
| commit | ab2af1f5005069321c5d130f09cce577b03f43ef (patch) | |
| tree | 73a70ba486f522cd9eeeef376ede2b5a1c1b473b /include/linux/init_task.h | |
| parent | 6e72ad2c581de121cc7e772469e2a8f6b1fd4379 (diff) | |
| download | lwn-ab2af1f5005069321c5d130f09cce577b03f43ef.tar.gz lwn-ab2af1f5005069321c5d130f09cce577b03f43ef.zip | |
[PATCH] files: files struct with RCU
Patch to eliminate struct files_struct.file_lock spinlock on the reader side
and use rcu refcounting rcuref_xxx api for the f_count refcounter. The
updates to the fdtable are done by allocating a new fdtable structure and
setting files->fdt to point to the new structure. The fdtable structure is
protected by RCU thereby allowing lock-free lookup. For fd arrays/sets that
are vmalloced, we use keventd to free them since RCU callbacks can't sleep. A
global list of fdtable to be freed is not scalable, so we use a per-cpu list.
If keventd is already handling the current cpu's work, we use a timer to defer
queueing of that work.
Since the last publication, this patch has been re-written to avoid using
explicit memory barriers and use rcu_assign_pointer(), rcu_dereference()
premitives instead. This required that the fd information is kept in a
separate structure (fdtable) and updated atomically.
Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/linux/init_task.h')
| -rw-r--r-- | include/linux/init_task.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/init_task.h b/include/linux/init_task.h index 94aefa54a1b5..68ab5f2ab9cd 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -2,6 +2,7 @@ #define _LINUX__INIT_TASK_H #include <linux/file.h> +#include <linux/rcupdate.h> #define INIT_FDTABLE \ { \ @@ -11,12 +12,16 @@ .fd = &init_files.fd_array[0], \ .close_on_exec = &init_files.close_on_exec_init, \ .open_fds = &init_files.open_fds_init, \ + .rcu = RCU_HEAD_INIT, \ + .free_files = NULL, \ + .next = NULL, \ } #define INIT_FILES \ { \ .count = ATOMIC_INIT(1), \ .file_lock = SPIN_LOCK_UNLOCKED, \ + .fdt = &init_files.fdtab, \ .fdtab = INIT_FDTABLE, \ .close_on_exec_init = { { 0, } }, \ .open_fds_init = { { 0, } }, \ |