Re: The effects of WITNESS and INVARIANTS

From: Willem Jan Withagen (wjw_at_withagen.nl)
Date: 02/24/04

  • Next message: Robert Watson: "Re: The effects of WITNESS and INVARIANTS" 
    To: "Robert Watson" <rwatson@FreeBSD.ORG>
Date: Tue, 24 Feb 2004 23:10:47 +0100

    From: "Robert Watson" <rwatson@FreeBSD.ORG>
    > 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.

    Hi Robert,

    I understand your concern and will take your remark as made here, and put it
    in the document as a "Nota Bene"...
    And I'll emphasise the fact that the 5-stable fact is the turning corner for
    this matter.

    --WjW
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  • Next message: Robert Watson: "Re: The effects of WITNESS and INVARIANTS"

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