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For the sysvsem undo, each task struct contains a sysv_sem structure with
a pointer to the undo information.
This pointer is only necessary if sysvipc is enabled - thus the pointer
can be made conditional on CONFIG_SYSVIPC.
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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include/linux/sem.h contains several structures that are only used within
ipc/sem.c.
The patch moves them into ipc/sem.c - there is no need to expose the
structures to the whole kernel.
No functional changes, only whitespace cleanups and 80-char per line
fixes.
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This allows us to move duplicated code in <asm/atomic.h>
(atomic_inc_not_zero() for now) to <linux/atomic.h>
Signed-off-by: Arun Sharma <asharma@fb.com>
Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Cacheline align the spinlock for sysv semaphores. Without the patch, the
spinlock and sem_otime [written by every semop that modified the array]
and sem_base [read in the hot path of try_atomic_semop()] can be in the
same cacheline.
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Zach Brown <zach.brown@oracle.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Based on Nick's findings:
sysv sem has the concept of semaphore arrays that consist out of multiple
semaphores. Atomic operations that affect multiple semaphores are
supported.
The patch is the first step for optimizing simple, single semaphore
operations: In addition to the global list of all pending operations, a
2nd, per-semaphore list with the simple operations is added.
Note: this patch does not make sense by itself, the new list is used
nowhere.
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The attached patch:
- reverses the locking order of ulp->lock and sem_lock:
Previously, it was first ulp->lock, then inside sem_lock.
Now it's the other way around.
- converts the undo structure to rcu.
Benefits:
- With the old locking order, IPC_RMID could not kfree the undo structures.
The stale entries remained in the linked lists and were released later.
- The patch fixes a a race in semtimedop(): if both IPC_RMID and a semget() that
recreates exactly the same id happen between find_alloc_undo() and sem_lock,
then semtimedop() would access already kfree'd memory.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Reviewed-by: Nadia Derbey <Nadia.Derbey@bull.net>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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sem_array.sem_pending is a double linked list, the attached patch converts
it to struct list_head.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Reviewed-by: Nadia Derbey <Nadia.Derbey@bull.net>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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sem_queue.sma and sem_queue.id were never used, the attached patch removes
them.
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Reviewed-by: Nadia Derbey <Nadia.Derbey@bull.net>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The undo structures contain two linked lists, the attached patch replaces
them with generic struct list_head lists.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This patch introduces ipcs storage into IDRs. The main changes are:
. This ipc_ids structure is changed: the entries array is changed into a
root idr structure.
. The grow_ary() routine is removed: it is not needed anymore when adding
an ipc structure, since we are now using the IDR facility.
. The ipc_rmid() routine interface is changed:
. there is no need for this routine to return the pointer passed in as
argument: it is now declared as a void
. since the id is now part of the kern_ipc_perm structure, no need to
have it as an argument to the routine
Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: David Woodhouse <dwmw2@infradead.org>
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Fix more include file problems that surfaced since I submitted the previous
fix-missing-includes.patch. This should now allow not to include sched.h
from module.h, which is done by a followup patch.
Signed-off-by: Tim Schmielau <tim@physik3.uni-rostock.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Change the /proc/sysvipc/shm|sem|msg files to use the generic seq_file
implementation for struct ipc_ids.
Signed-off-by: Mike Waychison <mikew@google.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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My patch that removed the spin_lock calls from the tail of sys_semtimedop
introduced a bug:
Before my patch was merged, every operation that altered an array called
update_queue. That call woke up threads that were waiting until a
semaphore value becomes 0. I've accidentially removed that call.
The attached patch fixes that by modifying update_queue: the function now
loops internally and wakes up all threads. The patch also removes
update_queue calls from the error path of sys_semtimedop: failed operations
do not modify the array, no need to rescan the list of waiting threads.
Signed-Off-By: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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From: Manfred Spraul <manfred@colorfullife.com>
cleanup of sysv ipc as a preparation for posix message queues:
- replace !CONFIG_SYSVIPC wrappers for copy_semundo and exit_sem with
static inline wrappers. Now the whole ipc/util.c file is only used if
CONFIG_SYSVIPC is set, use makefile magic instead of #ifdef.
- remove the prototypes for copy_semundo and exit_sem from kernel/fork.c
- they belong into a header file.
- create a new msgutil.c with the helper functions for message queues.
- cleanup the helper functions: run Lindent, add __user tags.
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From: "Randy.Dunlap" <rddunlap@osdl.org>
Add syscalls.h, which contains prototypes for the kernel's system calls.
Replace open-coded declarations all over the place. This patch found a
couple of prior bugs. It appears to be more important with -mregparm=3 as we
discover more asmlinkage mismatches.
Some syscalls have arch-dependent arguments, so their prototypes are in the
arch-specific unistd.h. Maybe it should have been asm/syscalls.h, but there
were already arch-specific syscall prototypes in asm/unistd.h...
Tested on x86, ia64, x86_64, ppc64, s390 and sparc64. May cause
trivial-to-fix build breakage on other architectures.
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From: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
This patch proposes a performance fix for the current IPC semaphore
implementation.
There are two shortcoming in the current implementation:
try_atomic_semop() was called two times to wake up a blocked process,
once from the update_queue() (executed from the process that wakes up
the sleeping process) and once in the retry part of the blocked process
(executed from the block process that gets woken up).
A second issue is that when several sleeping processes that are eligible
for wake up, they woke up in daisy chain formation and each one in turn
to wake up next process in line. However, every time when a process
wakes up, it start scans the wait queue from the beginning, not from
where it was last scanned. This causes large number of unnecessary
scanning of the wait queue under a situation of deep wait queue.
Blocked processes come and go, but chances are there are still quite a
few blocked processes sit at the beginning of that queue.
What we are proposing here is to merge the portion of the code in the
bottom part of sys_semtimedop() (code that gets executed when a sleeping
process gets woken up) into update_queue() function. The benefit is two
folds: (1) is to reduce redundant calls to try_atomic_semop() and (2) to
increase efficiency of finding eligible processes to wake up and higher
concurrency for multiple wake-ups.
We have measured that this patch improves throughput for a large
application significantly on a industry standard benchmark.
This patch is relative to 2.5.72. Any feedback is very much
appreciated.
Some kernel profile data attached:
Kernel profile before optimization:
-----------------------------------------------
0.05 0.14 40805/529060 sys_semop [133]
0.55 1.73 488255/529060 ia64_ret_from_syscall
[2]
[52] 2.5 0.59 1.88 529060 sys_semtimedop [52]
0.05 0.83 477766/817966 schedule_timeout [62]
0.34 0.46 529064/989340 update_queue [61]
0.14 0.00 1006740/6473086 try_atomic_semop [75]
0.06 0.00 529060/989336 ipcperms [149]
-----------------------------------------------
0.30 0.40 460276/989340 semctl_main [68]
0.34 0.46 529064/989340 sys_semtimedop [52]
[61] 1.5 0.64 0.87 989340 update_queue [61]
0.75 0.00 5466346/6473086 try_atomic_semop [75]
0.01 0.11 477676/576698 wake_up_process [146]
-----------------------------------------------
0.14 0.00 1006740/6473086 sys_semtimedop [52]
0.75 0.00 5466346/6473086 update_queue [61]
[75] 0.9 0.89 0.00 6473086 try_atomic_semop [75]
-----------------------------------------------
Kernel profile with optimization:
-----------------------------------------------
0.03 0.05 26139/503178 sys_semop [155]
0.46 0.92 477039/503178 ia64_ret_from_syscall
[2]
[61] 1.2 0.48 0.97 503178 sys_semtimedop [61]
0.04 0.79 470724/784394 schedule_timeout [62]
0.05 0.00 503178/3301773 try_atomic_semop [109]
0.05 0.00 503178/930934 ipcperms [149]
0.00 0.03 32454/460210 update_queue [99]
-----------------------------------------------
0.00 0.03 32454/460210 sys_semtimedop [61]
0.06 0.36 427756/460210 semctl_main [75]
[99] 0.4 0.06 0.39 460210 update_queue [99]
0.30 0.00 2798595/3301773 try_atomic_semop [109]
0.00 0.09 470630/614097 wake_up_process [146]
-----------------------------------------------
0.05 0.00 503178/3301773 sys_semtimedop [61]
0.30 0.00 2798595/3301773 update_queue [99]
[109] 0.3 0.35 0.00 3301773 try_atomic_semop [109]
-----------------------------------------------=20
Both number of function calls to try_atomic_semop() and update_queue()
are reduced by 50% as a result of the merge. Execution time of
sys_semtimedop is reduced because of the reduction in the low level
functions.
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From: Manfred Spraul <manfred@colorfullife.com>
The CLONE_SYSVSEM implementation is racy: it does an (atomic_read(->refcnt)
==1) instead of atomic_dec_and_test calls in the exit handling. The patch
fixes that.
Additionally, the patch contains the following changes:
- lock_undo() locks the list of undo structures. The lock is held
throughout the semop() syscall, but that's unnecessary - we can drop it
immediately after the lookup.
- undo structures are only allocated when necessary. The need for undo
structures is only noticed in the middle of the semop operation, while
holding the semaphore array spinlock. The result is a convoluted
unlock&revalidate implementation. I've reordered the code, and now the
undo allocation can happen before acquiring the semaphore array spinlock.
As a bonus, less code runs under the semaphore array spinlock.
- sysvsem.sleep_list looks like code to handle oopses: if an oops kills a
thread that sleeps in sys_timedsemop(), then sem_exit tries to recover.
I've removed that - too fragile.
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Patch from Mark Fasheh <mark.fasheh@oracle.com> (plus a few cleanups
and a speedup from yours truly)
Adds the semtimedop() function - semop with a timeout. Solaris has
this. It's apparently worth a couple of percent to Oracle throughput
and given the simplicity, that is sufficient benefit for inclusion IMO.
This patch hooks up semtimedop() only for ia64 and ia32.
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M68k: Fix missing/superfluous includes
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As we discussed some time ago, here is a patch for the SEM_UNDO change
that can be applied to linux-2.5.9.
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- me/Al Viro: fix bdget() oops with block device modules that don't
clean up after they exit
- Alan Cox: continued merging (drivers, license tags)
- David Miller: sparc update, network fixes
- Christoph Hellwig: work around broken drivers that add a gendisk more
than once
- Jakub Jelinek: handle more ELF loading special cases
- Trond Myklebust: NFS client and lockd reclaimer cleanups/fixes
- Greg KH: USB updates
- Mikael Pettersson: sparate out local APIC / IO-APIC config options
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