CPU VP Issue
A user running IDS 10.00.FC8 on a four-core Opteron RHEL box with four CPU VPs saw five to six threads constantly sitting on the ready queue even though the machine was over 60% idle, and asked whether to configure more CPU VPs than cores or whether something was misconfigured. Suggestions included checking that MULTIPROCESSOR was set (it was) and looking at I/O wait and top output, since idle CPU plus queued threads implies the VPs aren't being scheduled; another poster reported the same symptom on HP with many processors and blamed an OS bug. Memory/swap figures were discussed, but no resolution is recorded.
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I've got a puzzling CPU VP issue that I'm hoping someone else here has dealt with. I've got a dedicated database server running IDS 10.00.FC8 on a four-core RHEL Opteron server. We've configured four CPU VPs, one per core. There are almost always five to six threads sitting on the ready queue, despite the fact that the system is generally > 60% idle time. This sparks the age-old debate: add more CPU VPs than physical processor cores? Or is there something incorrectly configured about the _current_ setup that's causing my CPU VPs to do less than they should / yield too easily, etc.?
do you have set
MULTIPROCESSOR 1in $ONCONFIG
Superboer.
On 16 mei, 02:28, tgirsch <tgir...@NOSPAM.gmail.com> wrote:
> I've got a puzzling CPU VP issue that I'm hoping someone else here has
> dealt with. I've got a dedicated database server running IDS 10.00.FC8
> on a four-core RHEL Opteron server. We've configured four CPU VPs, one
> per core. There are almost always five to six threads sitting on the
> ready queue, despite the fact that the system is generally > 60% idle time.
>
> This sparks the age-old debate: add more CPU VPs than physical processor
> cores? Or is there something incorrectly configured about the _current_
> setup that's causing my CPU VPs to do less than they should / yield too
> easily, etc.?
Superboer wrote:
> do you have set
> MULTIPROCESSOR 1> in $ONCONFIG
>
Yes.
tgirsch wrote: > I've got a puzzling CPU VP issue that I'm hoping someone else here has > dealt with. I've got a dedicated database server running IDS 10.00.FC8 > on a four-core RHEL Opteron server. We've configured four CPU VPs, one > per core. There are almost always five to six threads sitting on the > ready queue, despite the fact that the system is generally > 60% idle time. If the system is showing idle time, and you have threads sitting in the ready queue, then there is somthing which is preventing the cpuvp from getting scheduled by the OS. What is the wait IO time? What does top look like? > > This sparks the age-old debate: add more CPU VPs than physical processor > cores? Or is there something incorrectly configured about the _current_ > setup that's causing my CPU VPs to do less than they should / yield too > easily, etc.?
Madison Pruet wrote: > tgirsch wrote: >> I've got a puzzling CPU VP issue that I'm hoping someone else here has >> dealt with. I've got a dedicated database server running IDS >> 10.00.FC8 on a four-core RHEL Opteron server. We've configured four >> CPU VPs, one per core. There are almost always five to six threads >> sitting on the ready queue, despite the fact that the system is >> generally > 60% idle time. > > If the system is showing idle time, and you have threads sitting in the > ready queue, then there is somthing which is preventing the cpuvp from > getting scheduled by the OS. What is the wait IO time? What does top > look like? > > >> >> This sparks the age-old debate: add more CPU VPs than physical >> processor cores? Or is there something incorrectly configured about >> the _current_ setup that's causing my CPU VPs to do less than they >> should / yield too easily, etc.? Seen the same thing on HP when you get to larger number of procesors, larger IDS ready queues but low OS CPU usage. Put it down to a OS bug Cheers Paul
Paul Watson (Oninit) wrote: > Madison Pruet wrote: > >> tgirsch wrote: >> >>> I've got a puzzling CPU VP issue that I'm hoping someone else here >>> has dealt with. I've got a dedicated database server running IDS >>> 10.00.FC8 on a four-core RHEL Opteron server. We've configured four >>> CPU VPs, one per core. There are almost always five to six threads >>> sitting on the ready queue, despite the fact that the system is >>> generally > 60% idle time. >> >> >> If the system is showing idle time, and you have threads sitting in >> the ready queue, then there is somthing which is preventing the cpuvp >> from getting scheduled by the OS. What is the wait IO time? What >> does top look like? >> >> >>> >>> This sparks the age-old debate: add more CPU VPs than physical >>> processor cores? Or is there something incorrectly configured about >>> the _current_ setup that's causing my CPU VPs to do less than they >>> should / yield too easily, etc.? > > > Seen the same thing on HP when you get to larger number of procesors, > larger IDS ready queues but low OS CPU usage. Put it down to a OS bug > > Cheers > Paul RAM vs SWAP vs IDS memory?
[cutting] >>>> >>>> This sparks the age-old debate: add more CPU VPs than physical >>>> processor cores? Or is there something incorrectly configured about >>>> the _current_ setup that's causing my CPU VPs to do less than they >>>> should / yield too easily, etc.? >> >> >> Seen the same thing on HP when you get to larger number of procesors, >> larger IDS ready queues but low OS CPU usage. Put it down to a OS bug >> >> Cheers >> Paul > > RAM vs SWAP vs IDS memory? 48GB vs 48GB vs 12GB Cheers Paul