Re: pg 8.1.3, AIX, huge box, painfully slow.

On Fri, 07 Apr 2006 17:56:49 -0400
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> This is not good. Did the semop storms coincide with visible
> slowdown? (I'd assume so, but you didn't actually say...)

If I'd been able to tell, then I'd tell you =) I'll have another go...

Yes, there's a definate correlation here.. I attached truss to the
main postmaster..

$ truss -Ff -p 340344 2>&1 | grep semop

here's a snippet

278774: __semop(15728650, 0x0FFFFFFFFFFF7E80, 1) = 0
155712: __semop(15728650, 0x0FFFFFFFFFFF5920, 1) = 0
278774: __semop(15728649, 0x0FFFFFFFFFFF6F10, 1)
114914: __semop(15728649, 0x0FFFFFFFFFFF6A40, 1) = 0 = 0
114914: __semop(15728650, 0x0FFFFFFFFFFF61E0, 1)
155712: __semop(15728650, 0x0FFFFFFFFFFF6850, 1) = 0 = 0
155712: __semop(15728650, 0x0FFFFFFFFFFF6890, 1) = 0 1
55712: __semop(15728650, 0x0FFFFFFFFFFF5920, 1)
278774: __semop(15728650, 0x0FFFFFFFFFFF6F10, 1)
155712: __semop(15728650, 0x0FFFFFFFFFFF6850, 1) = 0 = 0
278774: __semop(15728649, 0x0FFFFFFFFFFF7E40, 1)
114914: __semop(15728649, 0x0FFFFFFFFFFF6A80, 1) = 0 = 0
278774: __semop(15728650, 0x0FFFFFFFFFFF7E80, 1)

And when I saw a flood of semop's for any particular PID, a second later
in the 'topas' process list would show that PID at a 100% CPU ...

Most intriguing :)

Cheers,
Gavin.