On Wed, Jan 4, 2012 at 4:02 PM, Kevin Grittner <kevin.gritt...@wicourts.gov> wrote: > Robert Haas <robertmh...@gmail.com> wrote: > >> 2. The CLOG code isn't designed to manage a large number of >> buffers, so adding more might cause a performance regression on >> small systems. >> >> On Nate Boley's 32-core system, running pgbench at scale factor >> 100, the optimal number of buffers seems to be around 32. I'd >> like to get some test results from smaller systems - any chance >> you (or anyone) have, say, an 8-core box you could test on? > > Hmm. I can think of a lot of 4-core servers I could test on. (We > have a few poised to go into production where it would be relatively > easy to do benchmarking without distorting factors right now.) > After that we jump to 16 cores, unless I'm forgetting something. > These are currently all in production, but some of them are > redundant machines which could be pulled for a few hours here and > there for benchmarks. If either of those seem worthwhile, please > spec the useful tests so I can capture the right information.
Yes, both of those seem useful. To compile, I do this:
./configure --prefix=$HOME/install/$BRANCHNAME --enable-depend
--enable-debug ${EXTRA_OPTIONS}
make
make -C contrib/pgbench
make check
make install
make -C contrib/pgbench install
In this case, the relevant builds would probably be (1) master, (2)
master with NUM_CLOG_BUFFERS = 16, (3) master with NUM_CLOG_BUFFERS =
32, and (4) master with NUM_CLOG_BUFFERS = 48. (You could also try
intermediate numbers if it seems warranted.)
Basic test setup:
rm -rf $PGDATA
~/install/master/bin/initdb
cat >> $PGDATA/postgresql.conf <<EOM;
shared_buffers = 8GB
maintenance_work_mem = 1GB
synchronous_commit = off
checkpoint_segments = 300
checkpoint_timeout = 15min
checkpoint_completion_target = 0.9
wal_writer_delay = 20ms
EOM
I'm attaching a driver script you can modify to taste.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
runtestw
Description: Binary data
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