Re: [PATCH v2 8/8] simplebench/bench_block_job: drop caches before test run

[John Snow <jsnow@redhat.com>]

On 3/5/21 4:11 AM, Vladimir Sementsov-Ogievskiy wrote:
> 05.03.2021 04:30, John Snow wrote:
>> On 3/4/21 5:17 AM, Vladimir Sementsov-Ogievskiy wrote:
>>> It probably may improve reliability of results when testing in cached
>>> mode.
>>>
>>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>>> ---
>>>   scripts/simplebench/bench_block_job.py | 2 ++
>>>   1 file changed, 2 insertions(+)
>>>
>>> diff --git a/scripts/simplebench/bench_block_job.py 
>>> b/scripts/simplebench/bench_block_job.py
>>> index 4f03c12169..fa45ad2655 100755
>>> --- a/scripts/simplebench/bench_block_job.py
>>> +++ b/scripts/simplebench/bench_block_job.py
>>> @@ -53,6 +53,8 @@ def bench_block_job(cmd, cmd_args, qemu_args):
>>>           return {'error': 'qemu failed: ' + str(vm.get_log())}
>>>       try:
>>> +        subprocess.run('sync; echo 3 > /proc/sys/vm/drop_caches', 
>>> shell=True,
>>> +                       check=True)
>>>           res = vm.qmp(cmd, **cmd_args)
>>>           if res != {'return': {}}:
>>>               vm.shutdown()
>>>
>>
>> Worth adding a conditional to allow "hot" or "cold" runs? nah?
>>
> 
> You mean, make this addition optional? Make sense
> 
> 

I was thinking (along the lines of allowing both old and new behavior, 
in case anyone except you used these scripts) of this sort of thing:

def bench_block_job(cmd, cmd_args, qemu_args, drop_cache=True): ...

I don't insist on it; I was just earnestly wondering if it had any 
utility. If it doesn't, don't respin on my account.

--js