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Subject[PATCH 09/13] perf evlist: Round mmap pages to power 2 - v2
Date
From: David Ahern <dsahern@gmail.com>

Currently perf requires the -m / --mmap_pages option to be a power of 2.

To be more user friendly perf should automatically round this up to the
next power of 2.

Currently:
$ perf record -m 3 -a -- sleep 1
--mmap_pages/-m value must be a power of two.sleep: Terminated

With patch:
$ perf record -m 3 -a -- sleep 1
rounding mmap pages size to 16384 (4 pages)
...

v2: Add bytes units to rounding message per Ingo's request. Other
suggestions (e.g., prefixing INFO) should be addressed by wrapping
pr_info to catch all instances.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1384267617-3446-3-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/evlist.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 3960560f873a..fb4727d3df85 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -710,7 +710,6 @@ int perf_evlist__parse_mmap_pages(const struct option *opt, const char *str,
{
unsigned int *mmap_pages = opt->value;
unsigned long pages, val;
- size_t size;
static struct parse_tag tags[] = {
{ .tag = 'B', .mult = 1 },
{ .tag = 'K', .mult = 1 << 10 },
@@ -726,11 +725,6 @@ int perf_evlist__parse_mmap_pages(const struct option *opt, const char *str,
if (val != (unsigned long) -1) {
/* we got file size value */
pages = PERF_ALIGN(val, page_size) / page_size;
- if (pages < (1UL << 31) && !is_power_of_2(pages)) {
- pages = next_pow2(pages);
- pr_info("rounding mmap pages size to %lu (%lu pages)\n",
- pages * page_size, pages);
- }
} else {
/* we got pages count value */
char *eptr;
@@ -741,14 +735,14 @@ int perf_evlist__parse_mmap_pages(const struct option *opt, const char *str,
}
}

- if (pages > UINT_MAX || pages > SIZE_MAX / page_size) {
- pr_err("--mmap_pages/-m value too big\n");
- return -1;
+ if (pages < (1UL << 31) && !is_power_of_2(pages)) {
+ pages = next_pow2(pages);
+ pr_info("rounding mmap pages size to %lu bytes (%lu pages)\n",
+ pages * page_size, pages);
}

- size = perf_evlist__mmap_size(pages);
- if (!size) {
- pr_err("--mmap_pages/-m value must be a power of two.");
+ if (pages > UINT_MAX || pages > SIZE_MAX / page_size) {
+ pr_err("--mmap_pages/-m value too big\n");
return -1;
}

--
1.8.1.4


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