Freeing vnodes.

From: Jeff Roberson (jroberson_at_chesapeake.net)
Date: 03/15/05

  • Next message: Stephan Uphoff: "Re: Freeing vnodes." 
    Date: Mon, 14 Mar 2005 21:38:49 -0500 (EST)
To: arch@freebsd.org

    I have a patch at http://www.chesapeake.net/~jroberson/freevnodes.diff
    that allows us to start reclaiming vnodes from the free list and release
    their memory. It also changes the semantics of wantfreevnodes, and makes
    getnewvnode() much prettier.

    The changes attempt to keep some number of vnodes, currently 2.5% of
    desiredvnodes, that are free in memory. Free vnodes are vnodes which
    have no references or pages in memory. For example, if an application
    simply stat's a vnode, it will end up on the free list at the end of the
    operation. The algorithm that is currently in place will immediately
    recycle these vnodes once there is enough pressure, which will cause us to
    do a full lookup and reread the inode, etc. as soon as it is stat'd again.

    This also removes the recycling from the getnewvnode() path. Instead, it
    is done by a new helper function that is called from vnlru_proc(). This
    function just frees vnodes from the head of the list until we reach our
    wantfreevnodes target.

    I haven't perf tested this yet, but I have a box that is doing a
    buildworld with a fairly constant freevnodes count which shows that vnodes
    are actually being uma_zfree'd.

    Comments? Anyone willing to do some perf tests for me?

    Thanks,
    Jeff
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  • Next message: Stephan Uphoff: "Re: Freeing vnodes."

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