PostgreSQL benchmarks (now with Linux numbers)

[Doug Barton]

On 02/23/2012 05:22, John Baldwin wrote:
> On Wednesday, February 22, 2012 9:59:02 pm Doug Barton wrote:
>> On 02/22/2012 01:42, Ivan Voras wrote:
>>> The Dragonfly team has recently liberated their VM from the giant lock and there are some interesting benchmarks comparing it to FreeBSD 9 and a 
> derivative of RedHat Enterprise Linux:
>>>
>>> http://leaf.dragonflybsd.org/mailarchive/kernel/2011-11/msg00008.html
>>>
>>> Other developments are described in their release notes: http://www.dragonflybsd.org/release30/
>>
>> The 4.5 times improvement by enabling kern.ipc.shm_use_phys is pretty
>> notable, what prevents us from enabling that by default?
> 
> It makes all your SYSV SHMs wired.  That's fine if you are running a dedicated
> server using SYSV SHMs where you want that process to use all the RAM in the
> machine (e.g. a pgqsl server).  It's not so great for a general purpose load
> where you would like an otherwise-idle process using SYSV SHMs to have the SHMs
> paged out to swap if other processes on the machine need memory and the box is
> under memory pressure.

I see, thanks for that explanation.


Doug

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