Re: Speed up Clog Access by increasing CLOG buffers - Mailing list pgsql-hackers

From Dilip Kumar
Subject Re: Speed up Clog Access by increasing CLOG buffers
Date
Msg-id CAFiTN-sAPN5yUeDfOAf0WZYKH-Mj+2Wa7mqx-ejM7CXVL4pNNw@mail.gmail.com
Whole thread Raw
In response to Re: Speed up Clog Access by increasing CLOG buffers  (Tomas Vondra <tomas.vondra@2ndquadrant.com>)
List pgsql-hackers
On Sat, Sep 17, 2016 at 6:54 AM, Tomas Vondra
<tomas.vondra@2ndquadrant.com> wrote:
> Although most of the changes probably does not matter much for unlogged
> tables (I planned to see how this affects regular tables, but as I see no
> difference for unlogged ones, I haven't done that yet).
>
> So the question is why Dilip sees +30% improvement, while my results are
> almost exactly the same. Looking at Dilip's benchmark, I see he only ran the
> test for 10 seconds, and I'm not sure how many runs he did, warmup etc.
> Dilip, can you provide additional info?

Actually I ran test for 10 minutes.

Sorry for the confusion (I copy paste my script and manually replaced
the variable and made mistake )

My script is like this

scale_factor=300
shared_bufs=8GB
time_for_reading=600

./postgres -c shared_buffers=8GB -c checkpoint_timeout=40min -c
max_wal_size=20GB -c max_connections=300 -c maintenance_work_mem=1GB&
./pgbench -i -s $scale_factor --unlogged-tables postgres
./pgbench -c $threads -j $threads -T $time_for_reading -M prepared
postgres -f ../../script.sql >> test_results.txt

I am taking median of three readings..

with below script, I can repeat my results every time (64 client 15%
gain on head and 128+ client 30% gain on head).

I will repeat my test with 8,16 and 32 client and post the results soon.

> \set aid random (1,30000000)
> \set tid random (1,3000)
>
> BEGIN;
> SELECT abalance FROM pgbench_accounts WHERE aid = :aid for UPDATE;
> SAVEPOINT s1;
> SELECT tbalance FROM pgbench_tellers WHERE tid = :tid for UPDATE;
> SAVEPOINT s2;
> SELECT abalance FROM pgbench_accounts WHERE aid = :aid for UPDATE;
> END;
> -----------


-- 
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com



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