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Subject[PATCH 09/13] tracing: use trace_seq_init to initize seq field in trace_iterator
the size of seq field in trace_iterator is more than PAGE_SIZE, so
seq memset is expensive, try to use cheap seq init method: trace_seq_init

Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
---
kernel/trace/trace.c | 10 ++++++----
kernel/trace/trace_kdb.c | 5 +++--
2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 4cec7b8..c7cc915 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3551,9 +3551,10 @@ waitagain:
cnt = PAGE_SIZE - 1;

/* reset all but tr, trace, and overruns */
- memset(&iter->seq, 0,
+ trace_seq_init(&iter->seq);
+ memset(&iter->ent, 0,
sizeof(struct trace_iterator) -
- offsetof(struct trace_iterator, seq));
+ offsetof(struct trace_iterator, ent));
iter->pos = -1;

trace_event_read_lock();
@@ -5167,9 +5168,10 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
cnt++;

/* reset all but tr, trace, and overruns */
- memset(&iter.seq, 0,
+ trace_seq_init(&iter.seq);
+ memset(&iter.ent, 0,
sizeof(struct trace_iterator) -
- offsetof(struct trace_iterator, seq));
+ offsetof(struct trace_iterator, ent));
iter.iter_flags |= TRACE_FILE_LAT_FMT;
iter.pos = -1;

diff --git a/kernel/trace/trace_kdb.c b/kernel/trace/trace_kdb.c
index 6489b2e..84f1584 100644
--- a/kernel/trace/trace_kdb.c
+++ b/kernel/trace/trace_kdb.c
@@ -37,9 +37,10 @@ static void ftrace_dump_buf(int skip_lines, long cpu_file)
kdb_printf("Dumping ftrace buffer:\n");

/* reset all but tr, trace, and overruns */
- memset(&iter.seq, 0,
+ trace_seq_init(&iter.seq);
+ memset(&iter.ent, 0,
sizeof(struct trace_iterator) -
- offsetof(struct trace_iterator, seq));
+ offsetof(struct trace_iterator, ent));
iter.iter_flags |= TRACE_FILE_LAT_FMT;
iter.pos = -1;

--
1.7.9.7



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