Re: Performance tuning on FreeBSD

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On Mon, Mar 3, 2008 at 5:11 PM, Greg Smith <gsmith@xxxxxxxxxxxxx> wrote:
> On Mon, 3 Mar 2008, alan bryan wrote:
>
>  >> pgbench -c 100 -t 1000 testdb
>
> > tps = 558.013714 (excluding connections establishing)
>  >
>  > Just for testing, I tried turning off fsync and got:
>
> > tps = 4061.662041 (excluding connections establishing)
>
>  This is odd.  ~500 is what I expect from this test when there is no write
>  cache to accelerate fsync, while ~4000 is normal for your class of
>  hardware when you have such a cache.  Since you say your 3Ware card is
>  setup with a cache and a BBU, that's suspicious--you should be able to get
>  around 4000 with fsync on.  Any chance you have the card set to
>  write-through instead of write-back?  That's the only thing that comes to
>  mind that would cause this.
>
>  --
>  * Greg Smith gsmith@xxxxxxxxxxxxx http://www.gregsmith.com Baltimore, MD
>


According to 3dm2 the cache is on.  I even tried setting The StorSave
preference to "Performance" with no real benefit.  There seems to be
something really wrong with disk performance.  Here's the results from
bonnie:

File './Bonnie.2551', size: 104857600
Writing with putc()...done
Rewriting...done
Writing intelligently...done
Reading with getc()...done
Reading intelligently...done
Seeker 1...Seeker 2...Seeker 3...start 'em...done...done...done...
             -------Sequential Output-------- ---Sequential Input-- --Random--
             -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
         100  9989  4.8  6739  1.0 18900  7.8 225973 98.5 1914662
99.9 177210.7 259.7

This is on FreeBSD 7.0-Release.  I tried ULE and 4BSD schedulers with
no difference.  Maybe I'll try FreeBSD 6.3 to see what that does?

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