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Thread: Long pauses

  1. #1
    Join Date
    Oct 2007
    Posts
    51

    Default Long pauses

    I'm seeing long pauses happen in some 3d applications or ones that use opengl. I'm talking about complete system pauses, total lag of some sort. Compiz does this, it seems to degrade so that it happens more often and the pauses are longer. It doesn't happen for all 3d, but I assume for the ones that does it's the same bug. This seems to happen particularly when opengl is used for 2d like for playing video. It doesn't seem to happen with regular 3d applications like games and such. Is this known and is there a work around?

  2. #2
    Join Date
    Jan 2008
    Posts
    294

    Default

    You could try using the kernel boot option

    nopat

  3. #3
    Join Date
    Oct 2007
    Posts
    51

    Default

    Thanks, looks like that was it. At least it's back to how it used to be, pauses very short if anything, much better. I should have known about a PAT issue but I just didn't see it posted anywhere.

  4. #4
    Join Date
    Jul 2008
    Location
    Greece
    Posts
    3,790

    Default

    What's this "PAT" thing anyway? I can imagine it being enabled must be "a good thing" and Catalyst getting broken by it "a bad thing?"

  5. #5
    Join Date
    Oct 2007
    Posts
    51

    Default

    As I understand it, it's a newer type of MTRR (memory type range register) in more recent linux.

  6. #6
    Join Date
    Jul 2008
    Location
    Greece
    Posts
    3,790

    Default

    Funny thing is, fglrx says "[fglrx] PAT is enabled successfully!" regardless of whether the nopat kernel option is used or not. The difference is that the freezes are gone with nopat.

  7. #7
    Join Date
    Oct 2007
    Location
    Toronto-ish
    Posts
    7,458

    Default

    My dim understanding is that MTRR lets you set memory attributes (cached, write combining etc..) on an entire range at a time (easy but not precise) while PAT allows the driver or OS to adjust the settings on a page-by-page basis.

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