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-rw-r--r--tools/perf/builtin-top.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 2b4914f34ed6..b7c823ba8374 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -889,8 +889,10 @@ static void perf_top__mmap_read(struct perf_top *top)
{
bool overwrite = top->record_opts.overwrite;
struct perf_evlist *evlist = top->evlist;
+ unsigned long long start, end;
int i;
+ start = rdclock();
if (overwrite)
perf_evlist__toggle_bkw_mmap(evlist, BKW_MMAP_DATA_PENDING);
@@ -901,6 +903,13 @@ static void perf_top__mmap_read(struct perf_top *top)
perf_evlist__toggle_bkw_mmap(evlist, BKW_MMAP_EMPTY);
perf_evlist__toggle_bkw_mmap(evlist, BKW_MMAP_RUNNING);
}
+ end = rdclock();
+
+ if ((end - start) > (unsigned long long)top->delay_secs * NSEC_PER_SEC)
+ ui__warning("Too slow to read ring buffer.\n"
+ "Please try increasing the period (-c) or\n"
+ "decreasing the freq (-F) or\n"
+ "limiting the number of CPUs (-C)\n");
}
/*