linux-kernel - [PATCH] Fixes hang in zstd compression test by changing the source of random data.

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Date:   Thu, 22 Aug 2019 13:55:15 +0000
From:   James Clark <James.Clark@....com>
To:     "peterz@...radead.org" <peterz@...radead.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "acme@...nel.org" <acme@...nel.org>,
        "alexander.shishkin@...ux.intel.com" 
        <alexander.shishkin@...ux.intel.com>,
        "jolsa@...hat.com" <jolsa@...hat.com>,
        "namhyung@...nel.org" <namhyung@...nel.org>,
        "alexey.budankov@...ux.intel.com" <alexey.budankov@...ux.intel.com>
CC:     "linux-perf-users@...r.kernel.org" <linux-perf-users@...r.kernel.org>,
        nd <nd@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jeremy Linton <Jeremy.Linton@....com>
Subject: [PATCH] Fixes hang in zstd compression test by changing the source of
 random data.

Running 'perf test' with zstd compression linked will hang at the test
'Zstd perf.data compression/decompression' because /dev/random blocks
reads until there is enough entropy. This means that the test will
appear to never complete unless the mouse is continually moved while
running it.

Signed-off-by: James Clark <james.clark@....com>
---
 tools/perf/tests/shell/record+zstd_comp_decomp.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/tests/shell/record+zstd_comp_decomp.sh b/tools/perf/tests/shell/record+zstd_comp_decomp.sh
index 899604d1..63a91ec 100755
--- a/tools/perf/tests/shell/record+zstd_comp_decomp.sh
+++ b/tools/perf/tests/shell/record+zstd_comp_decomp.sh
@@ -13,7 +13,7 @@ skip_if_no_z_record() {
 collect_z_record() {
 	echo "Collecting compressed record file:"
 	$perf_tool record -o $trace_file -g -z -F 5000 -- \
-		dd count=500 if=/dev/random of=/dev/null
+		dd count=500 if=/dev/urandom of=/dev/null
 }
 
 check_compressed_stats() {
-- 
2.7.4