Re: Should we cacheline align PGXACT?

On Tue, Feb 21, 2017 at 4:21 PM, Alexander Korotkov
<a(dot)korotkov(at)postgrespro(dot)ru> wrote:
>
> Hi, Ashutosh!
> On Mon, Feb 20, 2017 at 1:20 PM, Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com> wrote:
>>
>> Following are the pgbench results for read-write workload, I got with pgxact-align-3 patch. The results are for 300 scale factor with 8GB of shared buffer i.e. when data fits into the shared buffer. For 1000 scale factor with 8GB shared buffer the test is still running, once it is completed I will share the results for that as well.
>>
>> pgbench settings:
>> pgbench -i -s 300 postgres
>> pgbench -M prepared -c $thread -j $thread -T $time_for_reading postgres
>>
>> where, time_for_reading = 30mins
>>
>> non default GUC param:
>> shared_buffers=8GB
>> max_connections=300
>>
>> pg_xlog is located in SSD.
>
>
> Thank you for testing.
> It seems that there is still regression. While padding was reduced from 116 bytes to 4 bytes, it makes me think that probably there is something wrong in testing methodology.
> Are you doing re-initdb and pgbench -i before each run? I would ask you to do the both.
> Also, if regression would still exist, let's change the order of versions. Thus, if you run master before patched version, I would ask you to run patched version before master.

Yes, there is still some regression however it has come down by a
small margin. I am not doing initdb for each run instead I am doing,
dropdb-->createdb-->pgbench -i. Is dropping old database and creating
a new one for every run not okay, Do I have to do initdb every time.
Okay, I can change the order of reading and let you know the results.