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Message-ID: <1461723563-67451-2-git-send-email-wangnan0@huawei.com>
Date: Wed, 27 Apr 2016 02:19:20 +0000
From: Wang Nan <wangnan0@...wei.com>
To: <acme@...nel.org>
CC: <linux-kernel@...r.kernel.org>, Wang Nan <wangnan0@...wei.com>,
"Arnaldo Carvalho de Melo" <acme@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Zefan Li <lizefan@...wei.com>, <pi3orama@....com>
Subject: [PATCH v2 1/4] perf tools: Extract perf_mmap__read()
Extract event reader from perf_evlist__mmap_read() to perf__mmap_read().
Future commit will feed it with manually computed 'head' and 'old'
pointers.
Signed-off-by: Wang Nan <wangnan0@...wei.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Zefan Li <lizefan@...wei.com>
Cc: pi3orama@....com
---
tools/perf/util/evlist.c | 39 ++++++++++++++++++++++++---------------
1 file changed, 24 insertions(+), 15 deletions(-)
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 85271e5..96c7191 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -679,24 +679,15 @@ static struct perf_evsel *perf_evlist__event2evsel(struct perf_evlist *evlist,
return NULL;
}
-union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)
+static union perf_event *
+perf_mmap__read(struct perf_mmap *md, bool overwrite, u64 head,
+ u64 old, u64 *prev)
{
- struct perf_mmap *md = &evlist->mmap[idx];
- u64 head;
- u64 old = md->prev;
- int diff;
unsigned char *data = md->base + page_size;
union perf_event *event = NULL;
+ int diff = head - old;
- /*
- * Check if event was unmapped due to a POLLHUP/POLLERR.
- */
- if (!atomic_read(&md->refcnt))
- return NULL;
-
- head = perf_mmap__read_head(md);
- diff = head - old;
- if (evlist->overwrite) {
+ if (overwrite) {
/*
* If we're further behind than half the buffer, there's a chance
* the writer will bite our tail and mess up the samples under us.
@@ -751,11 +742,29 @@ union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)
}
broken_event:
- md->prev = old;
+ if (prev)
+ *prev = old;
return event;
}
+union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)
+{
+ struct perf_mmap *md = &evlist->mmap[idx];
+ u64 head;
+ u64 old = md->prev;
+
+ /*
+ * Check if event was unmapped due to a POLLHUP/POLLERR.
+ */
+ if (!atomic_read(&md->refcnt))
+ return NULL;
+
+ head = perf_mmap__read_head(md);
+
+ return perf_mmap__read(md, evlist->overwrite, head, old, &md->prev);
+}
+
static bool perf_mmap__empty(struct perf_mmap *md)
{
return perf_mmap__read_head(md) == md->prev && !md->auxtrace_mmap.base;
--
1.8.3.4
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