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    SubjectRe: Scaling noise
    On Wed, 3 Sep 2003 19:46:08 -0700
    Larry McVoy <> wrote:

    > Here's the litmus test: list all the locks in the kernel and the locking
    > hierarchy. If you, a self claimed genius, can't do it, how can the rest
    > of us mortals possibly do it? Quick. You have 30 seconds, I want a list.
    > A complete list with the locking hierarchy, no silly awk scripts. You have
    > to show which locks can deadlock, from memory.
    > No list? Cool, you just proved my point.

    No point Larry, asking the same question about how the I/O
    path works sans the locks will give you the same blank stare.

    I absolutely do not accept the complexity argument. We have a fully
    scalable kernel now. Do you know why? It's not because we have some
    weird genius trolls writing the code, it's because of our insanely
    huge testing base.

    People give a lot of credit to the people writing the code in the
    Linux kernel which actually belongs to the people running the
    code. :-)

    That's where the other systems failed, all the in-house stress
    testing in the world is not going to find the bugs we do find in
    Linux. That's why Solaris goes out buggy and with all kinds of
    SMP deadlocks, their tester base is just too small to hit all
    the important bugs.

    FWIW, I actually can list all the locks taken for the primary paths in
    the networking, and that's about as finely locked as we can make it.
    As can Alexey Kuznetsov...

    So again, if you're going to argue against huge SMP (at least to me),
    don't use the locking complexity argument. Not only have we basically
    conquered it, we've along the way found some amazing ways to find
    locking bugs both at runtime and at compile time. You can even debug
    them on uniprocessor systems. And this doesn't even count the
    potential things we can do with Linus's sparse tool.
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