diff options
author | Davidlohr Bueso <davidlohr.bueso@hp.com> | 2013-04-30 22:15:29 -0400 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-05-01 11:12:58 -0400 |
commit | 16df3674efe39f3ab63e7052f1244dd3d50e7f84 (patch) | |
tree | 45ecd49ba72e0b84dbaac338d79173ba1ea4c972 /ipc/util.h | |
parent | 444d0f621b64716f7868dcbde448e0c66ece4e61 (diff) |
ipc,sem: do not hold ipc lock more than necessary
Instead of holding the ipc lock for permissions and security checks, among
others, only acquire it when necessary.
Some numbers....
1) With Rik's semop-multi.c microbenchmark we can see the following
results:
Baseline (3.9-rc1):
cpus 4, threads: 256, semaphores: 128, test duration: 30 secs
total operations: 151452270, ops/sec 5048409
+ 59.40% a.out [kernel.kallsyms] [k] _raw_spin_lock
+ 6.14% a.out [kernel.kallsyms] [k] sys_semtimedop
+ 3.84% a.out [kernel.kallsyms] [k] avc_has_perm_flags
+ 3.64% a.out [kernel.kallsyms] [k] __audit_syscall_exit
+ 2.06% a.out [kernel.kallsyms] [k] copy_user_enhanced_fast_string
+ 1.86% a.out [kernel.kallsyms] [k] ipc_lock
With this patchset:
cpus 4, threads: 256, semaphores: 128, test duration: 30 secs
total operations: 273156400, ops/sec 9105213
+ 18.54% a.out [kernel.kallsyms] [k] _raw_spin_lock
+ 11.72% a.out [kernel.kallsyms] [k] sys_semtimedop
+ 7.70% a.out [kernel.kallsyms] [k] ipc_has_perm.isra.21
+ 6.58% a.out [kernel.kallsyms] [k] avc_has_perm_flags
+ 6.54% a.out [kernel.kallsyms] [k] __audit_syscall_exit
+ 4.71% a.out [kernel.kallsyms] [k] ipc_obtain_object_check
2) While on an Oracle swingbench DSS (data mining) workload the
improvements are not as exciting as with Rik's benchmark, we can see
some positive numbers. For an 8 socket machine the following are the
percentages of %sys time incurred in the ipc lock:
Baseline (3.9-rc1):
100 swingbench users: 8,74%
400 swingbench users: 21,86%
800 swingbench users: 84,35%
With this patchset:
100 swingbench users: 8,11%
400 swingbench users: 19,93%
800 swingbench users: 77,69%
[riel@redhat.com: fix two locking bugs]
[sasha.levin@oracle.com: prevent releasing RCU read lock twice in semctl_main]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Chegu Vinod <chegu_vinod@hp.com>
Acked-by: Michel Lespinasse <walken@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Jason Low <jason.low2@hp.com>
Cc: Emmanuel Benisty <benisty.e@gmail.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc/util.h')
-rw-r--r-- | ipc/util.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/ipc/util.h b/ipc/util.h index 13d92fea15a3..c36b9977c957 100644 --- a/ipc/util.h +++ b/ipc/util.h | |||
@@ -171,6 +171,11 @@ static inline void ipc_unlock(struct kern_ipc_perm *perm) | |||
171 | rcu_read_unlock(); | 171 | rcu_read_unlock(); |
172 | } | 172 | } |
173 | 173 | ||
174 | static inline void ipc_lock_object(struct kern_ipc_perm *perm) | ||
175 | { | ||
176 | spin_lock(&perm->lock); | ||
177 | } | ||
178 | |||
174 | struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id); | 179 | struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id); |
175 | struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id); | 180 | struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id); |
176 | int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, | 181 | int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, |