Re: The effects of WITNESS and INVARIANTS

From: Robert Watson (rwatson_at_FreeBSD.ORG)
Date: 02/24/04

  • Next message: Nikos Ntarmos: "Re: Bad performance on alpha? (make buildworld)" 
    Date: Tue, 24 Feb 2004 14:28:43 -0500 (EST)
To: Willem Jan Withagen <wjw@withagen.nl>

    On Tue, 24 Feb 2004, Willem Jan Withagen wrote:

    > Just out of curriousity, and 'cause I've got some idle boxes, I started
    > to do some (NFS-)performance testing. There is still a long way to go,
    > but I've but a first obvious result online running on the local server
    > disk.
    >
    > It makes the claims of the effects of WITNESS and INVARIANTS very
    > obvious. Look especially at the graph for "Sequential block read".
    >
    > You might want to have a look at:
    > http://withagen.dyndns.org/FreeBSD/nfs-performance/index.html. Note
    > that no NFS data is included. I have some Bonnie-NFS data, but need to
    > write accompanying test and conclusions for it.
    >
    > Suggestions are more than welcomed.

    My primary suggestion is "Turn off WITNESS and INVARIANTS when
    benchmarking or for production systems". We turn them off in releases,
    and once 5.x becomes 5-stable, we'll turn it off by default also. However,
    they're invaluable tools when debugging the development system, so we have
    them on in the development branch by default. I would encourage people to
    generally run with them turned on unless performance of a system requires
    them to be off, as it really helps the debugging process, as well as
    helping to identify locking problems as the system evolves.

    Robert N M Watson FreeBSD Core Team, TrustedBSD Projects
    robert@fledge.watson.org Senior Research Scientist, McAfee Research

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    • Re: The effects of WITNESS and INVARIANTS
      ... > It makes the claims of the effects of WITNESS and INVARIANTS very ... > that no NFS data is included. ... they're invaluable tools when debugging the development system, ... them to be off, as it really helps the debugging process, as well as ...
      (freebsd-current)
    • Re: The effects of WITNESS and INVARIANTS
      ... >> It makes the claims of the effects of WITNESS and INVARIANTS very ... > they're invaluable tools when debugging the development system, ... > them to be off, as it really helps the debugging process, as well as ...
      (freebsd-current)
    • Re: The effects of WITNESS and INVARIANTS
      ... >> It makes the claims of the effects of WITNESS and INVARIANTS very ... > they're invaluable tools when debugging the development system, ... > them to be off, as it really helps the debugging process, as well as ...
      (freebsd-performance)