Re: odd -CURRENT performance issue

From: John Baldwin (jhb_at_FreeBSD.org)
Date: 02/08/05

  • Next message: John Baldwin: "Re: odd -CURRENT performance issue" 
    To: freebsd-current@FreeBSD.org
Date: Tue, 8 Feb 2005 13:26:14 -0500

    On Monday 07 February 2005 06:49 pm, Don Lewis wrote:
    > time make all-depends-list
    > ten times in a row in /usr/ports/x11/gnome2. The system was freshly
    > booted, and other than a niced setiathome, the system was idle. I got
    > the following results:
    >
    > 122.63 real 29.83 user 66.29 sys
    > 117.86 real 29.58 user 66.55 sys
    > 119.89 real 29.80 user 67.27 sys
    > 121.68 real 30.31 user 67.55 sys
    > 122.10 real 30.41 user 67.66 sys
    > 120.90 real 29.67 user 68.24 sys
    > 121.21 real 30.27 user 67.69 sys
    > 219.85 real 30.35 user 148.12 sys
    > 312.54 real 30.49 user 224.79 sys
    > 312.83 real 30.23 user 225.83 sys
    >
    > The last three lines are rather strange ...
    >
    > Kernel and world are 6.0-CURRENT, built from February 3rd sources.
    > WITNESS, INVARIANTS, DEBUG_VFS_LOCKS, and SMP enabled, and it is fairly
    > close to GENERIC.

    WITNESS has especially poor scalability issues and can get much worse as more
    lock classes and relationships are added to its tree due to how it tries to
    rebalance the tree every time it adds a new relationship (and each rebalance
    is O(n) I think). If you turn off witness via sysctl debug.witness.watch=0,.
    does the same weirdness persist? 

    -- 
John Baldwin <jhb@FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org
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  • Next message: John Baldwin: "Re: odd -CURRENT performance issue"

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