| From: | "Guillaume Smet" <guillaume(dot)smet(at)gmail(dot)com> |
|---|---|
| To: | "Simon Riggs" <simon(at)2ndquadrant(dot)com> |
| Cc: | pgsql-performance <pgsql-performance(at)postgresql(dot)org>, "Stefan Kaltenbrunner" <stefan(at)kaltenbrunner(dot)cc> |
| Subject: | Re: More shared buffers causes lower performances |
| Date: | 2007-12-26 17:20:15 |
| Message-ID: | 1d4e0c10712260920g7a440fam4363a886f60fa700@mail.gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
On Dec 26, 2007 4:41 PM, Guillaume Smet <guillaume(dot)smet(at)gmail(dot)com> wrote:
> Then I decided to perform read-only tests using -S option (pgbench -S
> -s 100 -c 16 -t 30000 -U postgres bench). And still the same
> behaviour:
> shared_buffers=64MB : 20k tps
> shared_buffers=1024MB : 8k tps
Some more information. If I strace the backends during the test, the
test is faster with shared_buffers=1024MB and I have less system calls
(less read and less lseek).
A quick cut | uniq | sort gives me:
With 64MB:
12548 semop
160039 sendto
160056 recvfrom
294289 read
613338 lseek
With 1024MB:
11396 semop
129947 read
160039 sendto
160056 recvfrom
449584 lseek
--
Guillaume
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Chris Hoover | 2007-12-26 17:36:15 | Anyone running on RHEL Cluster? |
| Previous Message | Pavel Stehule | 2007-12-26 17:12:21 | Re: More shared buffers causes lower performances |