Re: sysbench throughput degradation in 4.13+

Eric Farman
2017-09-22T16:12:50Z

On 09/22/2017 11:53 AM, Peter Zijlstra wrote:
> On Fri, Sep 22, 2017 at 11:03:39AM -0400, Eric Farman wrote:
>> Hi Peter, Rik,
>>
>> With OSS last week, I'm sure this got lost in the deluge, so here's a
>> friendly ping.
>
> Very much so, inbox is a giant trainwreck ;-)

My apologies. :)

>
>> I picked up 4.14.0-rc1 earlier this week, and still see the
>> degradation described above. Not really a surprise, since I don't see any
>> other commits in this area beyond the ones I mentioned in my original note.
>>
>> Anyway, I'm unsure what else to try or what doc to pull to help debug this,
>> and would appreciate your expertise here. We can repro this pretty easily
>> as necessary to help get to the bottom of this.
>>
>> Many thanks in advance,
>
> Could you describe your sysbench setup? Are you running it on mysql or
> postgresql, what other options?
>

MySQL. We've tried a few different configs with both test=oltp and
test=threads, but both show the same behavior. What I have settled on
for my repro is the following:

sudo sysbench --db-driver=mysql --mysql-host=localhost --mysql-user=root
--mysql-db=test1 --max-time=180 --max-requests=100000000 --num-threads=8
--test=oltp prepare
sudo sysbench --db-driver=mysql --mysql-host=localhost --mysql-user=root
--mysql-db=test1 --max-time=180 --max-requests=100000000 --num-threads=8
--test=oltp run

Have also some environments where multiple sysbench instances are run
concurrently (I've tried up to 8, with db's test1-8 being specified),
but doesn't appear to much matter either.

- Eric