Re: postgresql 8.3 tps rate

Hi Craig,

Here is the result. It seems that disk write is terrible!.

root(at)myserver /usr]# time (dd if=/dev/zero of=bigfile bs=8192
count=1000000; sync)

1000000+0 records in
1000000+0 records out
8192000000 bytes transferred in 945.343806 secs (8665630 bytes/sec)

real 15m46.206s
user 0m0.368s
sys 0m15.560s
[root(at)myserver /usr]#

[root(at)myserver /usr]# time dd if=bigfile of=/dev/null bs=8192
1000000+0 records in
1000000+0 records out
8192000000 bytes transferred in 174.646798 secs (46906099 bytes/sec)

real 2m54.663s
user 0m0.246s
sys 0m9.307s

On Fri, Jan 23, 2009 at 12:44 AM, Craig James
<craig_james(at)emolecules(dot)com> wrote:
> David Rees wrote:
>>
>> On Thu, Jan 22, 2009 at 1:27 PM, Ibrahim Harrani
>> <ibrahim(dot)harrani(at)gmail(dot)com> wrote:
>>>
>>> Version 1.93d ------Sequential Output------ --Sequential Input-
>>> --Random-
>>> Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
>>> --Seeks--
>>> Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP
>>> /sec %CP
>>> myserver 300M 391 97 9619 1 8537 2 673 99 +++++ +++ 1196 16
>>> Latency 211ms 388ms 325ms 27652us 722us
>>> 6720ms
>>> Version 1.93d ------Sequential Create------ --------Random
>>> Create--------
>>> myserver -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
>>> files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec
>>> %CP
>>> 16 9004 25 +++++ +++ +++++ +++ 8246 20 +++++ +++ +++++
>>> +++
>>> Latency 592ms 208us 102us 673ms 179us
>>> 100us
>>
>> You should be testing bonnie with a file size that is at least double
>> the amount of memory in your machine - in this case, 4GB files, not
>> 300MB files.
>>
>>> When I compare my bonnie++ result with the one at
>>> http://www.westnet.com/~gsmith/content/postgresql/pg-disktesting.htm,
>>> It seems that there is something wrong with the disks!?
>>
>> Yes, your machine appears to be very slow. You should be able to
>> write in the order of 30-50MB/s+ and read in the order of 40-80MB/s+.
>> Random IO should be in the 200 tps range for a 7200rpm SATA RAID1.
>
> Have you tried the really basic speed test?
>
> time (dd if=/dev/zero of=bigfile bs=8192 count=1000000; sync)
>
> time dd if=bigfile of=/dev/null bs=8192
>
> Divide 8.2GB by the times reported. On a single 10K SATA drive, I get about
> 55MB/sec write and 61 MB/sec read.
>
> If you can't get similar numbers, then something is wrong.
>
> Craig
>