On 30/04/13 20:46, Merlin Moncure wrote:
> On Tue, Apr 30, 2013 at 12:26 PM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
>> On Tue, Apr 30, 2013 at 8:28 AM, Andrew Hastie <andrew(at)ahastie(dot)net> wrote:
>>> I'm currently working on a project porting an application from RedHat
>>> Linux on Intel onto IBM zLinux. Our application requires PostgreSQL at
>>> version 9.n, so the PostgreSQL binaries have been built using the standard
>>> build tools from source. Everything appears run correctly. However as part
>>> of performance testing, our IBM and Linux SysProgs have been "poking around"
>>> using strace and have reported the following (which they think is an error
>>> condition) when hooking up to the postmaster processes:-
>>>
>>> read(3, 0x3ffff875ee0, 16) = -1 EAGAIN (Resource temporarily unavailable)
>>> poll([{fd=3, events=POLLIN}, {fd=6, events=POLLIN}], 2, 200) = 0 (Timeout)
>>> read(3, 0x3ffff875ee0, 16) = -1 EAGAIN (Resource temporarily unavailable)
>>> poll([{fd=3, events=POLLIN}, {fd=6, events=POLLIN}], 2, 10000) = 0
>>> (Timeout)
>>> ... repeated many times
>>>
>>
>> That does not look like the postmaster process. It looks like probably the
>> background writer process.
>>
>> It is normal, and doesn't explain high CPU utilization.
> yeah: we're probably a couple of steps in front of deep system
> profiling. Helpful things to provide to help diagnose would be:
>
> *) 'explain analyze' of the queries that are eating cpu
> *) more details about the hardware -- how many cpu, etc.
> *) better definition of 'perceived high CPU utilisation'
> *) some correlating performance tests, expecially cpu bound pgbench
> tests (pgbench -S)
>
> merlin
>
>
I'm not sure how much experience the community has on tuning PostgreSQL
running on RedHat which in turn is hosted on an IBM mainframe under VM
(using zLinux). So I'm happy to start posting further details and
benchmark results and see where we go. Should I be moving this thread
over into the pg-performance list, or is pg-general the right place?