perf tools: Add possibility to specify mmap size

Adding possibility to specify mmap size via -m/--mmap-pages
by appending unit size character (B/K/M/G) to the
number, like:
  $ perf record -m 8K ls
  $ perf record -m 2M ls

The size is rounded up appropriately to follow perf
mmap restrictions.

If no unit is specified the number provides pages as
of now, like:
  $ perf record -m 8 ls

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1378031796-17892-3-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 26 insertions, 6 deletions

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 4283f49..d21ab08 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -687,14 +687,33 @@ static size_t perf_evlist__mmap_size(unsigned long pages)
 int perf_evlist__parse_mmap_pages(const struct option *opt, const char *str,
 				  int unset __maybe_unused)
 {
-	unsigned int pages, *mmap_pages = opt->value;
+	unsigned int pages, val, *mmap_pages = opt->value;
 	size_t size;
-	char *eptr;
+	static struct parse_tag tags[] = {
+		{ .tag  = 'B', .mult = 1       },
+		{ .tag  = 'K', .mult = 1 << 10 },
+		{ .tag  = 'M', .mult = 1 << 20 },
+		{ .tag  = 'G', .mult = 1 << 30 },
+		{ .tag  = 0 },
+	};
 
-	pages = strtoul(str, &eptr, 10);
-	if (*eptr != '\0') {
-		pr_err("failed to parse --mmap_pages/-m value\n");
-		return -1;
+	val = parse_tag_value(str, tags);
+	if (val != (unsigned int) -1) {
+		/* we got file size value */
+		pages = PERF_ALIGN(val, page_size) / page_size;
+		if (!is_power_of_2(pages)) {
+			pages = next_pow2(pages);
+			pr_info("rounding mmap pages size to %u (%u pages)\n",
+				pages * page_size, pages);
+		}
+	} else {
+		/* we got pages count value */
+		char *eptr;
+		pages = strtoul(str, &eptr, 10);
+		if (*eptr != '\0') {
+			pr_err("failed to parse --mmap_pages/-m value\n");
+			return -1;
+		}
 	}
 
 	size = perf_evlist__mmap_size(pages);
@@ -738,6 +757,7 @@ int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
 
 	evlist->overwrite = overwrite;
 	evlist->mmap_len = perf_evlist__mmap_size(pages);
+	pr_debug("mmap size %luB\n", evlist->mmap_len);
 	mask = evlist->mmap_len - page_size - 1;
 
 	list_for_each_entry(evsel, &evlist->entries, node) {