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automatically set processor affinity mask not checked

On Database » Microsoft SQL Server

5,126 words with 3 Comments; publish: Sun, 01 Jun 2008 23:25:00 GMT; (250109.38, « »)

I take that by default for multi CPU machines, the "Automatically set

processor affinity mask for all processors" is checked in the properties of

the server in SQL 2005

My question is, if its not checked, what does that mean and what are the

pros and cons of it ?

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  • 3 Comments
    • Check out sp_configure and the "affinity mask" option. Checking the checkbox means 0 (all processors

      can be used). Un.checking this box is setting it to some other bitmask, where you specify which

      processors can be used.

      --

      Tibor Karaszi, SQL Server MVP

      http://www.karaszi.com/sqlserver/default.asp

      http://sqlblog.com/blogs/tibor_karaszi

      "Hassan" <hassan.sqlserver.questionfor.info.test.com> wrote in message news:OPwvm$7VIHA.2304.sqlserver.questionfor.info.TK2MSFTNGP06.phx.gbl...

      >I take that by default for multi CPU machines, the "Automatically set processor affinity mask for

      >all processors" is checked in the properties of the server in SQL 2005

      > My question is, if its not checked, what does that mean and what are the pros and cons of it ?

      >

      >

      #1; Sun, 01 Jun 2008 23:27:00 GMT
    • So how can I check which processors are being used ?

      If I look at the processors, all the processors are checked ?

      So in essence, is it the same thing as if this setting was checked ?

      "Tibor Karaszi" <tibor_please.no.email_karaszi.sqlserver.questionfor.info.hotmail.nomail.com> wrote in

      message news:A1C1FE69-965D-4A38-B1B8-D61E5CB38CD0.sqlserver.questionfor.info.microsoft.com...

      > Check out sp_configure and the "affinity mask" option. Checking the

      > checkbox means 0 (all processors can be used). Un.checking this box is

      > setting it to some other bitmask, where you specify which processors can

      > be used.

      > --

      > Tibor Karaszi, SQL Server MVP

      > http://www.karaszi.com/sqlserver/default.asp

      > http://sqlblog.com/blogs/tibor_karaszi

      >

      > "Hassan" <hassan.sqlserver.questionfor.info.test.com> wrote in message

      > news:OPwvm$7VIHA.2304.sqlserver.questionfor.info.TK2MSFTNGP06.phx.gbl...

      >>I take that by default for multi CPU machines, the "Automatically set

      >>processor affinity mask for all processors" is checked in the properties

      >>of the server in SQL 2005

      >> My question is, if its not checked, what does that mean and what are the

      >> pros and cons of it ?

      >>

      >

      #2; Sun, 01 Jun 2008 23:28:00 GMT
    • > So how can I check which processors are being used ?

      Configured to be used, or actually doing some work at a particular point in time? For the later, you

      can for instance use Task Manager. For the former, check your sp_configure setting.

      > If I look at the processors, all the processors are checked ?

      > So in essence, is it the same thing as if this setting was checked ?

      There is a slight difference between having all checked and the checkbox not checked (the later is

      value 0). SQL Server has as many schedulers as processors. With value 0, a scheduler isn't tied to a

      particular processor. With anything but 0, each scheduler is tied to a particular processor. If you

      want to dig more into schedulers, threads, workers etc, check out Kalen's Inside SQL Server 2005

      book.

      --

      Tibor Karaszi, SQL Server MVP

      http://www.karaszi.com/sqlserver/default.asp

      http://sqlblog.com/blogs/tibor_karaszi

      "Hassan" <hassan.sqlserver.questionfor.info.test.com> wrote in message news:eMOEut8VIHA.5132.sqlserver.questionfor.info.TK2MSFTNGP02.phx.gbl...

      > So how can I check which processors are being used ?

      > If I look at the processors, all the processors are checked ?

      > So in essence, is it the same thing as if this setting was checked ?

      > "Tibor Karaszi" <tibor_please.no.email_karaszi.sqlserver.questionfor.info.hotmail.nomail.com> wrote in message

      > news:A1C1FE69-965D-4A38-B1B8-D61E5CB38CD0.sqlserver.questionfor.info.microsoft.com...

      >> Check out sp_configure and the "affinity mask" option. Checking the checkbox means 0 (all

      >> processors can be used). Un.checking this box is setting it to some other bitmask, where you

      >> specify which processors can be used.

      >> --

      >> Tibor Karaszi, SQL Server MVP

      >> http://www.karaszi.com/sqlserver/default.asp

      >> http://sqlblog.com/blogs/tibor_karaszi

      >>

      >> "Hassan" <hassan.sqlserver.questionfor.info.test.com> wrote in message news:OPwvm$7VIHA.2304.sqlserver.questionfor.info.TK2MSFTNGP06.phx.gbl...

      >>I take that by default for multi CPU machines, the "Automatically set processor affinity mask for

      >>all processors" is checked in the properties of the server in SQL 2005

      >> My question is, if its not checked, what does that mean and what are the pros and cons of it ?

      >>

      >>

      >

      #3; Sun, 01 Jun 2008 23:29:00 GMT