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author | Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> | 2009-12-09 11:29:44 +0800 |
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committer | Ingo Molnar <mingo@elte.hu> | 2009-12-09 09:56:27 +0100 |
commit | b93f7978ad6b46133e9453b90ccc057dc2429e75 (patch) | |
tree | f3420ebd5fa80ddb1a4c3e302a64861146104385 /kernel/perf_event.c | |
parent | aa5452d70c0d559310598b243b8b1033c10056e7 (diff) | |
download | linux-stable-b93f7978ad6b46133e9453b90ccc057dc2429e75.tar.gz linux-stable-b93f7978ad6b46133e9453b90ccc057dc2429e75.tar.bz2 linux-stable-b93f7978ad6b46133e9453b90ccc057dc2429e75.zip |
perf_event: Allocate children's perf_event_ctxp at the right time
In current code, children task will allocate memory for
'child->perf_event_ctxp' if the parent is counted, we can
do it only if the parent allowed children inherit it.
It can save memory and reduce overhead.
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <4B1F19A8.5040805@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_event.c')
-rw-r--r-- | kernel/perf_event.c | 37 |
1 files changed, 22 insertions, 15 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 2b06c45bfba9..77641ae6b23f 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -5083,7 +5083,7 @@ again: */ int perf_event_init_task(struct task_struct *child) { - struct perf_event_context *child_ctx, *parent_ctx; + struct perf_event_context *child_ctx = NULL, *parent_ctx; struct perf_event_context *cloned_ctx; struct perf_event *event; struct task_struct *parent = current; @@ -5099,20 +5099,6 @@ int perf_event_init_task(struct task_struct *child) return 0; /* - * This is executed from the parent task context, so inherit - * events that have been marked for cloning. - * First allocate and initialize a context for the child. - */ - - child_ctx = kzalloc(sizeof(struct perf_event_context), GFP_KERNEL); - if (!child_ctx) - return -ENOMEM; - - __perf_event_init_context(child_ctx, child); - child->perf_event_ctxp = child_ctx; - get_task_struct(child); - - /* * If the parent's context is a clone, pin it so it won't get * swapped under us. */ @@ -5142,6 +5128,26 @@ int perf_event_init_task(struct task_struct *child) continue; } + if (!child->perf_event_ctxp) { + /* + * This is executed from the parent task context, so + * inherit events that have been marked for cloning. + * First allocate and initialize a context for the + * child. + */ + + child_ctx = kzalloc(sizeof(struct perf_event_context), + GFP_KERNEL); + if (!child_ctx) { + ret = -ENOMEM; + goto exit; + } + + __perf_event_init_context(child_ctx, child); + child->perf_event_ctxp = child_ctx; + get_task_struct(child); + } + ret = inherit_group(event, parent, parent_ctx, child, child_ctx); if (ret) { @@ -5170,6 +5176,7 @@ int perf_event_init_task(struct task_struct *child) get_ctx(child_ctx->parent_ctx); } +exit: mutex_unlock(&parent_ctx->mutex); perf_unpin_context(parent_ctx); |