CPU intensive Vs I/O intensive

  • Hi There,

    Im in a little confusion, both I/O and CPU are important part in performance perspective. But sometime I have heard " This is CPU intensive system and this is I/O intensive system".

    1. Actually what is it mean?

    2. Why this separation ?

    3. Any real time examples for I/O intensive environments and CPU intensive environments?

    Thanks

    Vignesh

  • In about 20 years of working with SQL Server, mostly as a consultant at a wide variety of clients I have come across only a few systems that were CPU bound. And each of those situations was resolved with some tuning work, including properly configuring/sizing some very poor virtual environments. I will jump through EXTREME hoops on virtually any SQL Server system out there to trade CPU ticks for IO - even when SSDs are in play! CPU ticks are just so much more available on modern systems than IO is.

    Best,
    Kevin G. Boles
    SQL Server Consultant
    SQL MVP 2007-2012
    TheSQLGuru on googles mail service

  • Example can be found on this blog, http://saveadba.blogspot.ca/2012/02/get-io-cpu-intensive-queries.html

  • TheSQLGuru (2/12/2015)


    In about 20 years of working with SQL Server, mostly as a consultant at a wide variety of clients I have come across only a few systems that were CPU bound.

    I saw one just last week. Not truly CPU-bound as the processes can't parallel so just send single cores to 100% for long periods, but heading that way fast. Flawed architecture unfortunately.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • GilaMonster (2/13/2015)


    TheSQLGuru (2/12/2015)


    In about 20 years of working with SQL Server, mostly as a consultant at a wide variety of clients I have come across only a few systems that were CPU bound.

    I saw one just last week. Not truly CPU-bound as the processes can't parallel so just send single cores to 100% for long periods, but heading that way fast. Flawed architecture unfortunately.

    What was blocking parallelism - Scalar UDFs by chance?

    Best,
    Kevin G. Boles
    SQL Server Consultant
    SQL MVP 2007-2012
    TheSQLGuru on googles mail service

  • TheSQLGuru (2/13/2015)


    GilaMonster (2/13/2015)


    TheSQLGuru (2/12/2015)


    In about 20 years of working with SQL Server, mostly as a consultant at a wide variety of clients I have come across only a few systems that were CPU bound.

    I saw one just last week. Not truly CPU-bound as the processes can't parallel so just send single cores to 100% for long periods, but heading that way fast. Flawed architecture unfortunately.

    What was blocking parallelism - Scalar UDFs by chance?

    And multi-statement UDFs and more table variables than you could throw a stick at (I counted 15 in one procedure, excluding the ones created by function execution or created within functions)

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

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