From: | Francois Tigeot <ftigeot(at)wolfpond(dot)org> |
---|---|
To: | pgsql-hackers(at)postgresql(dot)org |
Cc: | kernel(at)dragonflybsd(dot)org, tech-kern(at)NetBSD(dot)org |
Subject: | SYSV shared memory vs mmap performance |
Date: | 2012-09-13 06:30:03 |
Message-ID: | 20120913062959.GA967@sekishi.zefyris.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
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
Attachment | Content-Type | Size |
---|---|---|
Pg-benchmarks.2012-09.Sysv_shm.vs.mmap.pdf | application/pdf | 66.0 KB |
From | Date | Subject | |
---|---|---|---|
Next Message | Magnus Hagander | 2012-09-13 07:00:14 | Re: git author vs committer |
Previous Message | Amit Kapila | 2012-09-13 04:22:08 | Re: [BUGS] BUG #7534: walreceiver takes long time to detect n/w breakdown |