Re: Should we cacheline align PGXACT?

From: Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com>
To: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
Cc: Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, Robert Haas <robertmhaas(at)gmail(dot)com>, Bernd Helmle <mailings(at)oopsware(dot)de>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Should we cacheline align PGXACT?
Date: 2017-02-24 04:41:41
Message-ID: CAE9k0Pk+rCuNY+7O5XwVXHPuki9t8=M7jr4kevxw-hdkpFhS2A@mail.gmail.com
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Okay. As suggested by Alexander, I have changed the order of reading and
doing initdb for each pgbench run. With these changes, I got following
results at 300 scale factor with 8GB of shared buffer.

*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.

CLIENT COUNT TPS (HEAD) TPS (PATCH) % IMPROVEMENT
4 2803 2843 1.427042455
8 5315 5225 -1.69332079
32 19755 19669 -0.4353328271
64 28679 27980 -2.437323477
128 28887 28008 -3.042891266
156 27465 26728 -2.683415256
180 27425 26697 -2.654512306
196 28826 27396 -4.960799278
256 29787 28107 -5.640044315
The test machine details are as follows,

*Machine details:*
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 128
On-line CPU(s) list: 0-127
Thread(s) per core: 2
Core(s) per socket: 8
Socket(s): 8
NUMA node(s): 8
Vendor ID: GenuineIntel
CPU family: 6
Model: 47
Model name: Intel(R) Xeon(R) CPU E7- 8830 @ 2.13GHz

Also, Excel sheet (results-readwrite-300-SF) containing the results for all
the 3 runs is attached.

--
With Regards,
Ashutosh Sharma
EnterpriseDB:*http://www.enterprisedb.com <http://www.enterprisedb.com/>*

On Thu, Feb 23, 2017 at 2:44 AM, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
wrote:

> I wonder if this "perf c2c" tool with Linux 4.10 might be useful in
> studying this problem.
> https://joemario.github.io/blog/2016/09/01/c2c-blog/
>
> --
> Álvaro Herrera https://www.2ndQuadrant.com/
> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
>

Attachment Content-Type Size
results-readwrite-300-SF.xlsx application/vnd.openxmlformats-officedocument.spreadsheetml.sheet 7.2 KB

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