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Subject: Re: [PATCH 05/11] selftests: net/fcnal: kill_procs via spin instead
 of sleep
To:     David Ahern <dsahern@gmail.com>, Jakub Kicinski <kuba@kernel.org>,
        Shuah Khan <shuah@kernel.org>, David Ahern <dsahern@kernel.org>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Ido Schimmel <idosch@nvidia.com>,
        Seth David Schoen <schoen@loyalty.org>,
        netdev@vger.kernel.org, linux-kselftest@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <cover.1633520807.git.cdleonard@gmail.com>
 <ff71285715d47b8c9b6bedb3b50700a26bc81f41.1633520807.git.cdleonard@gmail.com>
 <b1a213d5-470d-637d-4e78-1b7653d87041@gmail.com>
From:   Leonard Crestez <cdleonard@gmail.com>
Message-ID: <7ac2b77d-4633-bd3e-c24f-ec87d34b4516@gmail.com>
Date:   Thu, 7 Oct 2021 00:16:11 +0300
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On 06.10.2021 17:45, David Ahern wrote:
> On 10/6/21 5:47 AM, Leonard Crestez wrote:
>> Sleeping for one second after a kill is not necessary and adds up quite
>> quickly. Replace with a fast loop spinning until pidof returns nothing.
>>
>> Signed-off-by: Leonard Crestez <cdleonard@gmail.com>
>> ---
>>   tools/testing/selftests/net/fcnal-test.sh | 11 +++++++++--
>>   1 file changed, 9 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/testing/selftests/net/fcnal-test.sh b/tools/testing/selftests/net/fcnal-test.sh
>> index 0bd60cd3bc06..b7fda51deb3f 100755
>> --- a/tools/testing/selftests/net/fcnal-test.sh
>> +++ b/tools/testing/selftests/net/fcnal-test.sh
>> @@ -176,12 +176,19 @@ show_hint()
>>   	fi
>>   }
>>   
>>   kill_procs()
>>   {
>> -	killall nettest ping ping6 >/dev/null 2>&1
>> -	sleep 1
>> +	local pids
>> +	while true; do
>> +		pids=$(pidof nettest ping ping6)
>> +		if [[ -z $pids ]]; then
>> +			break
>> +		fi
>> +		kill $pids
>> +		sleep 0.01
>> +	done
>>   }
>>   
>>   do_run_cmd()
>>   {
>>   	local cmd="$*"
>>
> 
> ideally the script keeps track of processes it launches and only kills
> those. The original killall was just a stop gap until the process
> tracking was added.

That's harder to do. This is much faster and not in any way worse than 
killall + sleep.

Some sort of a wrapper would have to added for each process running the 
background, for each run_ping_bg.

If nettest forks by itself then $! won't work, maybe some sort of 
--pid-file switch would be required?

--
Regards,
Leonard