Sent this to Claudio rather than the whole list ... here it is. On Wed, Oct 10, 2012 at 7:44 AM, Claudio Freire <klaussfre...@gmail.com>wrote:
> On Wed, Oct 10, 2012 at 9:52 AM, Shaun Thomas <stho...@optionshouse.com> > wrote: > > On 10/09/2012 06:30 PM, Craig James wrote: > > > >> ra:8192 walb:1M ra:256 walb:1M ra:256 walb:256kB > >> ---------------- ---------------- ----------------- > >> -c -t Run1 Run2 Run3 Run4 Run5 Run6 Run7 Run8 Run9 > >> 40 2500 4261 3722 4243 9286 9240 5712 9310 8530 8872 > >> 50 2000 4138 4399 3865 9213 9351 9578 8011 7651 8362 > > > > > > I think I speak for more than a few people here when I say: wat. > > > > About the only thing I can ask, is: did you make these tests fair? And by > > fair, I mean: > > > > echo 3 > /proc/sys/vm/drop_caches > > pg_ctl -D /your/pg/dir restart > > I showed the exact commands I used -- if it's not there, I didn't do it. So the answer is no, I didn't drop caches. On the other hand, I wanted to know what happened on cold start and after running for a while. Running pgbench once isn't as interesting as running it three times. > Yes, I was thinking the same. Especially if you check the tendency to > perform better in higher-numbered runs. But, as you said, that doesn't > explain that jump to twice the TPS. I was thinking, and I'm not > pgbench expert, could it be that the database grows from run to run, > changing performance characteristics? > > > My head hurts. > > I'm just confused. No headache yet. > > But really interesting numbers in any case. It these results are on > the level, then maybe the kernel's read-ahead algorithm isn't as > fool-proof as we thought? Gotta read the source. BRB > Big numbers, little numbers ... I'm just reporting what pgbench tells me and how I got them. I'm good at chemical databases, you guys are the Postgres performance experts.
