SYSV shared memory vs mmap performance
Francois Tigeot <[email protected]>
| Newsgroups | gmane.comp.db.postgresql.devel.general,gmane.os.dragonfly-bsd.kernel,gmane.os.netbsd.devel.kernel |
|---|---|
| Message-ID | <[email protected]> |
Hi, Given the recent decision to switch from SYSV shared memory to mmap and the concerns which were made with regard to performance on *BSD kernels, I've run a few Pgbench tests on a spare Xeon box. I tested PostgreSQL-9.3 from June 28th, as of commits: - c5b3451a8e72cb7825933d4f4827f467cb38b498 (mmap) - 5d594b73d988b1ac78c49d8a84deae6bae876d01 (sysv shared memory) I also used both Scientific Linux-6.2 and DragonFly BSD-3.1; the results are in the attached PDF document. To cut a long story short, Linux doesn't show any difference and DragonFly sees some heavy degradation under load. After a while, it starts swapping and performance goes to hell. The only *BSD system tested was DragonFly but I know from previous pgbench tests FreeBSD and NetBSD follow a similar performance curve The famous kern.ipc.shm_use_phys sysctl was set to 1, which is the default setting. -- Francois Tigeot -- Sent via pgsql-hackers mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Pg-benchmarks.2012-09.Sysv_shm.vs.mmap.pdf
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