From bc289ae98b75d93228d24f521ef02a076e506e94 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Thu, 3 Jun 2010 18:26:24 +0800 Subject: [PATCH] tracing: Reduce latency and remove percpu trace_seq __print_flags() and __print_symbolic() use percpu trace_seq: 1) Its memory is allocated at compile time, it wastes memory if we don't use tracing. 2) It is percpu data and it wastes more memory for multi-cpus system. 3) It disables preemption when it executes its core routine "trace_seq_printf(s, "%s: ", #call);" and introduces latency. So we move this trace_seq to struct trace_iterator. Signed-off-by: Lai Jiangshan LKML-Reference: <4C078350.7090106@cn.fujitsu.com> Signed-off-by: Steven Rostedt --- include/linux/ftrace_event.h | 5 +++-- include/trace/ftrace.h | 12 +++--------- kernel/trace/trace_output.c | 3 --- 3 files changed, 6 insertions(+), 14 deletions(-) diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h index 2b7b139..02b8b24 100644 --- a/include/linux/ftrace_event.h +++ b/include/linux/ftrace_event.h @@ -11,8 +11,6 @@ struct trace_array; struct tracer; struct dentry; -DECLARE_PER_CPU(struct trace_seq, ftrace_event_seq); - struct trace_print_flags { unsigned long mask; const char *name; @@ -58,6 +56,9 @@ struct trace_iterator { struct ring_buffer_iter *buffer_iter[NR_CPUS]; unsigned long iter_flags; + /* trace_seq for __print_flags() and __print_symbolic() etc. */ + struct trace_seq tmp_seq; + /* The below is zeroed out in pipe_read */ struct trace_seq seq; struct trace_entry *ent; diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h index 55c1fd1..fb783d9 100644 --- a/include/trace/ftrace.h +++ b/include/trace/ftrace.h @@ -145,7 +145,7 @@ * struct trace_seq *s = &iter->seq; * struct ftrace_raw_ *field; <-- defined in stage 1 * struct trace_entry *entry; - * struct trace_seq *p; + * struct trace_seq *p = &iter->tmp_seq; * int ret; * * entry = iter->ent; @@ -157,12 +157,10 @@ * * field = (typeof(field))entry; * - * p = &get_cpu_var(ftrace_event_seq); * trace_seq_init(p); * ret = trace_seq_printf(s, "%s: ", ); * if (ret) * ret = trace_seq_printf(s, "\n"); - * put_cpu(); * if (!ret) * return TRACE_TYPE_PARTIAL_LINE; * @@ -216,7 +214,7 @@ ftrace_raw_output_##call(struct trace_iterator *iter, int flags, \ struct trace_seq *s = &iter->seq; \ struct ftrace_raw_##call *field; \ struct trace_entry *entry; \ - struct trace_seq *p; \ + struct trace_seq *p = &iter->tmp_seq; \ int ret; \ \ event = container_of(trace_event, struct ftrace_event_call, \ @@ -231,12 +229,10 @@ ftrace_raw_output_##call(struct trace_iterator *iter, int flags, \ \ field = (typeof(field))entry; \ \ - p = &get_cpu_var(ftrace_event_seq); \ trace_seq_init(p); \ ret = trace_seq_printf(s, "%s: ", event->name); \ if (ret) \ ret = trace_seq_printf(s, print); \ - put_cpu(); \ if (!ret) \ return TRACE_TYPE_PARTIAL_LINE; \ \ @@ -255,7 +251,7 @@ ftrace_raw_output_##call(struct trace_iterator *iter, int flags, \ struct trace_seq *s = &iter->seq; \ struct ftrace_raw_##template *field; \ struct trace_entry *entry; \ - struct trace_seq *p; \ + struct trace_seq *p = &iter->tmp_seq; \ int ret; \ \ entry = iter->ent; \ @@ -267,12 +263,10 @@ ftrace_raw_output_##call(struct trace_iterator *iter, int flags, \ \ field = (typeof(field))entry; \ \ - p = &get_cpu_var(ftrace_event_seq); \ trace_seq_init(p); \ ret = trace_seq_printf(s, "%s: ", #call); \ if (ret) \ ret = trace_seq_printf(s, print); \ - put_cpu(); \ if (!ret) \ return TRACE_TYPE_PARTIAL_LINE; \ \ diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c index 57c1b45..1ba64d3 100644 --- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -16,9 +16,6 @@ DECLARE_RWSEM(trace_event_mutex); -DEFINE_PER_CPU(struct trace_seq, ftrace_event_seq); -EXPORT_PER_CPU_SYMBOL(ftrace_event_seq); - static struct hlist_head event_hash[EVENT_HASHSIZE] __read_mostly; static int next_event_type = __TRACE_LAST_TYPE + 1; -- 2.7.4