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

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Date:   Fri, 23 Aug 2019 09:00:10 +0300
From:   Alexey Budankov <alexey.budankov@...ux.intel.com>
To:     James Clark <James.Clark@....com>,
        "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>
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: Re: [PATCH] Fixes hang in zstd compression test by changing the
 source of random data.


On 22.08.2019 16:55, James Clark wrote:
> 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

Acked-by: Alexey Budankov <alexey.budankov@...ux.intel.com>

~Alexey

>  }
>  
>  check_compressed_stats() {
>