Re: vlan patch

From: Andrew Thompson (thompsa_at_freebsd.org)
Date: 10/20/05

  • Next message: Robert Watson: "Re: Network performance 6.0 with netperf" 
    Date: Thu, 20 Oct 2005 22:19:34 +1300
To: Gleb Smirnoff <glebius@FreeBSD.org>, yar@FreeBSD.org, ru@FreeBSD.org, freebsd-net@freebsd.org

    On Thu, Oct 20, 2005 at 11:00:54AM +0400, Gleb Smirnoff wrote:
    > Andrew,
    >
    > On Wed, Oct 19, 2005 at 11:25:59PM +1300, Andrew Thompson wrote:
    > A> It has always bugged me how the vlan code traverses the linked-list for
    > A> each incoming packet to find the right ifvlan, I have this patch which
    > A> attempts to fix this.
    > A>
    > A> What it does is replace the linear search for the vlan with a constant
    > A> time lookup. It does this by allocating an array for each vlan enabled
    > A> parent interface so the tag can be directly indexed.
    > A>
    > A> This has an overhead of ~16kb on 32bit, this is not too bad as there is
    > A> usually only one physical interface when using a large number of vlans.
    > A>
    > A> I have measured a 1.6% pps increase with 100 vlans, and 8% with 500, and
    > A> yes, some people use this many in production.
    > A>
    > A> It also has the benefit of enforcing unique vlan tags per parent which
    > A> the current code doesn't do.
    >
    > Although the memory overhead is not noticable on modern i386 and amd64
    > PCs I don't think that we should waste so much memory. We should keep
    > in mind the existence of embedded architectures with little memory.
    >

    I agree. Did you see the revised patch that sets a threshold before
    allocating the memory? do you think thats sufficient?

    Andrew
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  • Next message: Robert Watson: "Re: Network performance 6.0 with netperf"

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