January 1, 2003 at 2:11 pm
I have recently installed Win2K-Srv OS on a box with a multiprocessor motherboard with a single Zeon processor installed (IBM xServer 335).
The OS setup the CPU configuration as "ACPI Multiprocessor Machine". When I view the main property sheet for MS SqlServer Enter Ed., I see 'it' thinks there are 2 cpu's installed. From here, one of the cpu's that it is checked is hashed over, but can be unchecked. Should this be checked if there is physically only one Zeon installed ?
How should such a machine be properly configured from both the OS side, then in turn, within Sql Server ?
Any performance issues or strange behaviors that might come from such a configured machine ? Might SS be foiled in behaving as if running on a true SMP machine when it is not ?
January 1, 2003 at 4:07 pm
I personally don't have any experience with the new hyper threading on the intel chips it is suppose to be seamless to the OS so I would assume that there will only be an increase in performance. Not near what a true dual proc machine would be but it should better utilize the single processor you do have.
Wes
January 1, 2003 at 4:36 pm
quote:
I personally don't have any experience with the new hyper threading on the intel chips it is suppose to be seamless to the OS so I would assume that there will only be an increase in performance. Not near what a true dual proc machine would be but it should better utilize the single processor you do have.Wes
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What if the OS was configured as "ACPI SingleProcessor Machine " ,, does this ever play into how SS internals might process accordingly ? possible 'mis-processing' ?
MS says to configure smp capable motherbaord as "ACPI Multiprocessor Machine" if 2 cpus', as "ACPI Single Processor Machine" if smp capabable board but with one resident cpu. Mean anything from S/S perspective ?
Any idea why SQL hashes out the one 'checked' cpu entry, and not the one below it when you view the property sheet ?
Thanks for any thoughts or experiences. Rick
January 1, 2003 at 5:00 pm
If you configured the OS as single processor then hyper threading doesn't come into play at all the OS and SQL only "sees" one processor. Hyperthreading makes the OS "see" two processors on the hardware level. The OS is unaware if there really is two procs or one. Personally, I would have set up the OS as multiprocessor since Hyperthreading is handled in hardware.
Wes
January 1, 2003 at 5:18 pm
This is were the confusion comes in. Hyperthreading is inherent in the Zeon processor. I believe. As such, the OS will always think it has twice the cpu that is physically there. But a system is not SMP configured if only one cpu exists, even if the hardware is capable to support it. Should an element within this try to process as if it was in a true SMP environment with no real SMP implemented, could there negative consequences ? Why MS differentiates using either of these these two possible ACPI cpu settings, I do not know exactly. If i had the control, I would like to change the OS config to be "ACPI SingleProcessor machine" and then see if S/S sees this as a SMP - dual processor or not. Shaded or hashed out fields in any property sheet always raises my curiosity !
January 2, 2003 at 2:30 pm
I don't think we are on the same page. As far as the OS and SQL are conserned if you have a hyperthreading cpu and hyperthreading is enabled on the server in bios then the OS and SQL "see" two cpus. the OS and SQL don't know its only one. There are some good articles floating around the net like
http://www.arstechnica.com/paedia/h/hyperthreading/hyperthreading-1.html
is a very good read on hyperthreading and the problems you could see due to large amounts of memory swaping. Give that a go and see if it doesn't clear things up a bit.
Wes
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