Messages in this thread Patch in this message | | | Date | Tue, 26 Jun 2012 15:04:26 +0300 | From | "Kirill A. Shutemov" <> | Subject | [RFC, PATCH] CLONE_NEWIPC and exit_group() |
| |
Hi,
Patch to move kern_unmount() out of exit_group() code path is below. Dmitry, could you check if it's beneficial for your use-case?
Results are not that impressive. Microbenchmark:
#define _GNU_SOURCE #include <unistd.h> #include <sched.h> #include <stdlib.h> #include <sys/types.h> #include <sys/wait.h>
int main(int argc, char *argv[]) { int i;
for (i = 0; i < 1000; i++) { if (fork()) continue;
unshare(CLONE_NEWIPC); exit(0); }
while (wait(NULL) > 0) ;
return 0; }
Before:
Performance counter stats for './test' (10 runs):
2645.849247 task-clock # 3.203 CPUs utilized ( +- 3.43% ) 2,375 context-switches # 0.001 M/sec ( +- 0.35% ) 1,579 CPU-migrations # 0.001 M/sec ( +- 0.90% ) 37,516 page-faults # 0.014 M/sec ( +- 0.44% ) 5,739,887,800 cycles # 2.169 GHz ( +- 3.50% ) [84.21%] 5,126,092,712 stalled-cycles-frontend # 89.31% frontend cycles idle ( +- 3.78% ) [84.47%] 3,779,607,146 stalled-cycles-backend # 65.85% backend cycles idle ( +- 4.06% ) [68.26%] 1,210,768,660 instructions # 0.21 insns per cycle # 4.23 stalled cycles per insn ( +- 1.01% ) [86.28%] 213,318,802 branches # 80.624 M/sec ( +- 1.16% ) [84.49%] 2,417,038 branch-misses # 1.13% of all branches ( +- 0.70% ) [84.55%]
0.826165497 seconds time elapsed ( +- 1.26% )
After:
Performance counter stats for './test' (10 runs):
4248.846649 task-clock # 6.370 CPUs utilized ( +- 13.50% ) 2,343 context-switches # 0.001 M/sec ( +- 1.51% ) 1,624 CPU-migrations # 0.000 M/sec ( +- 2.53% ) 37,416 page-faults # 0.009 M/sec ( +- 0.41% ) 9,314,096,247 cycles # 2.192 GHz ( +- 13.64% ) [83.75%] 8,482,679,429 stalled-cycles-frontend # 91.07% frontend cycles idle ( +- 14.46% ) [83.79%] 5,807,497,239 stalled-cycles-backend # 62.35% backend cycles idle ( +- 14.79% ) [67.65%] 1,556,594,531 instructions # 0.17 insns per cycle # 5.45 stalled cycles per insn ( +- 5.41% ) [85.00%] 282,682,358 branches # 66.532 M/sec ( +- 5.56% ) [84.32%] 2,610,583 branch-misses # 0.92% of all branches ( +- 4.42% ) [83.90%]
0.667023551 seconds time elapsed ( +- 12.10% )
Any thoughts if it makes sense?
diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h index 5499c92..1a4cfd8 100644 --- a/include/linux/ipc_namespace.h +++ b/include/linux/ipc_namespace.h @@ -67,6 +67,8 @@ struct ipc_namespace { /* user_ns which owns the ipc ns */ struct user_namespace *user_ns; + + struct work_struct free_ns_work; }; extern struct ipc_namespace init_ipc_ns; diff --git a/ipc/namespace.c b/ipc/namespace.c index f362298c..edbf885 100644 --- a/ipc/namespace.c +++ b/ipc/namespace.c @@ -16,6 +16,8 @@ #include "util.h" +static void free_ns(struct work_struct *work); + static struct ipc_namespace *create_ipc_ns(struct task_struct *tsk, struct ipc_namespace *old_ns) { @@ -27,6 +29,7 @@ static struct ipc_namespace *create_ipc_ns(struct task_struct *tsk, return ERR_PTR(-ENOMEM); atomic_set(&ns->count, 1); + INIT_WORK(&ns->free_ns_work, free_ns); err = mq_init_ns(ns); if (err) { kfree(ns); @@ -116,6 +119,15 @@ static void free_ipc_ns(struct ipc_namespace *ns) kfree(ns); } +static void free_ns(struct work_struct *work) +{ + struct ipc_namespace *ns = container_of(work, struct ipc_namespace, + free_ns_work); + + mq_put_mnt(ns); + free_ipc_ns(ns); +} + /* * put_ipc_ns - drop a reference to an ipc namespace. * @ns: the namespace to put @@ -137,8 +149,7 @@ void put_ipc_ns(struct ipc_namespace *ns) if (atomic_dec_and_lock(&ns->count, &mq_lock)) { mq_clear_sbinfo(ns); spin_unlock(&mq_lock); - mq_put_mnt(ns); - free_ipc_ns(ns); + schedule_work(&ns->free_ns_work); } } -- Kirill A. Shutemov[unhandled content-type:application/pgp-signature] | |