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authorDavidlohr Bueso <davidlohr.bueso@hp.com>2013-04-30 22:15:29 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2013-05-01 11:12:58 -0400
commit16df3674efe39f3ab63e7052f1244dd3d50e7f84 (patch)
tree45ecd49ba72e0b84dbaac338d79173ba1ea4c972 /ipc/util.h
parent444d0f621b64716f7868dcbde448e0c66ece4e61 (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.h5
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
174static inline void ipc_lock_object(struct kern_ipc_perm *perm)
175{
176 spin_lock(&perm->lock);
177}
178
174struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id); 179struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id);
175struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id); 180struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
176int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, 181int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,