| Author |
Multiple processor and utilization
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| Bob Castleman 2005-07-05, 8:23 pm |
| We have recently upgraded our database server to 8 processors and 24 GB RAM.
THey are hyperhtreaded so it shows 16 logical processors. All this looks
fine. What looks weird to me is that some of the processors are showing 40%
load or so, while some of the others are only showing 3% load. Shouldn't
this load be spread more evenly? Is there any way to drill down into whats
going on to see if something is amiss?
Thanks,
Boc Castleman
DBA Poseur
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| David Gugick 2005-07-05, 8:23 pm |
| Bob Castleman wrote:
> We have recently upgraded our database server to 8 processors and 24
> GB RAM. THey are hyperhtreaded so it shows 16 logical processors. All
> this looks fine. What looks weird to me is that some of the
> processors are showing 40% load or so, while some of the others are
> only showing 3% load. Shouldn't this load be spread more evenly? Is
> there any way to drill down into whats going on to see if something
> is amiss?
> Thanks,
>
> Boc Castleman
> DBA Poseur
Not necessarily. Queries are mostly single threaded. Parallel queries
are possible, but in general most are single threaded and run on a
single CPU. If you run a heavy query, it could cause a 40% CPU spike on
a single CPU. That load would not be distributed to other CPUs by SQL
Server. However, SQL Server will attempt to distribute the load of
multiple queries to all available processors. Are you sure SQL Server is
set to use all processors? Check this from SQL Enterprise Manager and
make sure all available procs are checked.
--
David Gugick
Quest Software
www.imceda.com
www.quest.com
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| Bob Castleman 2005-07-06, 9:23 am |
| All processors are enabled. I'll just keep an eye on it. As we add more
load, I would expect to see the other processors to start showing more
activity.
Thanks.
"David Gugick" <david.gugick-nospam@quest.com> wrote in message
news:uYWgRqagFHA.3788@tk2msftngp13.phx.gbl...
> Bob Castleman wrote:
>
> Not necessarily. Queries are mostly single threaded. Parallel queries are
> possible, but in general most are single threaded and run on a single CPU.
> If you run a heavy query, it could cause a 40% CPU spike on a single CPU.
> That load would not be distributed to other CPUs by SQL Server. However,
> SQL Server will attempt to distribute the load of multiple queries to all
> available processors. Are you sure SQL Server is set to use all
> processors? Check this from SQL Enterprise Manager and make sure all
> available procs are checked.
>
> --
> David Gugick
> Quest Software
> www.imceda.com
> www.quest.com
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| David Gugick 2005-07-06, 9:23 am |
| Bob Castleman wrote:
> All processors are enabled. I'll just keep an eye on it. As we add
> more load, I would expect to see the other processors to start
> showing more activity.
That should be the case. If you still end up seeing spikes on specific
CPUs, you may want to fire up Profiler and look for high CPU queries.
--
David Gugick
Quest Software
www.imceda.com
www.quest.com
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| GlennThomas5 2005-07-06, 1:23 pm |
| just an FYI.
we had a 4 proc, 8 gig machine that would run an extensive cursor to
do some maintenance. It would spike a single CPU but not always the
same one. It was completely normal and after the job finished would
always return to the average load pct.
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| Bob Castleman 2005-07-06, 1:23 pm |
| We see spikes on individual CPUs during our transaction log backups. I
suppose I shouldn't complain when some of the processors are just sitting
there waiting to be used. Maybe I'm just paranoid. :)
Bob
"GlennThomas5" <glennthomas5@gmail.com> wrote in message
news:1120671268.326180.293860@g14g2000cwa.googlegroups.com...
> just an FYI.
>
> we had a 4 proc, 8 gig machine that would run an extensive cursor to
> do some maintenance. It would spike a single CPU but not always the
> same one. It was completely normal and after the job finished would
> always return to the average load pct.
>
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