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    SubjectRe: [PATCH 0/2] jump label: 2.6.38 updates
    * Jason Baron (jbaron@redhat.com) wrote:
    > On Mon, Feb 14, 2011 at 04:57:04PM +0100, Peter Zijlstra wrote:
    > > On Mon, 2011-02-14 at 10:51 -0500, Jason Baron wrote:
    > > > On Sat, Feb 12, 2011 at 07:47:45PM +0100, Peter Zijlstra wrote:
    > > > > On Fri, 2011-02-11 at 22:38 +0100, Peter Zijlstra wrote:
    > > > > >
    > > > > > So why can't we make that jump_label_entry::refcount and
    > > > > > jump_label_key::state an atomic_t and be done with it?
    > > > >
    > > > > So I had a bit of a poke at this because I didn't quite understand why
    > > > > all that stuff was as it was. I applied both Jason's patches and then
    > > > > basically rewrote kernel/jump_label.c just for kicks ;-)
    > > > >
    > > > > I haven't tried compiling this, let alone running it, but provided I
    > > > > didn't actually forget anything the storage per key is now 16 bytes when
    > > > > modules are disabled and 24 * (1 + mods) bytes for when they are
    > > > > enabled. The old code had 64 + 40 * mods bytes.
    > > > >
    > > > > I still need to clean up the static_branch_else bits and look at !x86
    > > > > aside from the already mentioned bits.. but what do people think?
    > > > >
    > > > > ---
    > > >
    > > > Generally, I really like this! Its the direction I think the jump label
    > > > code should be going. The complete removal of the hash table, makes the
    > > > design a lot better and simpler. We just need to get some of the details
    > > > cleaned up, and of course we need this to compile :) But I don't see any
    > > > fundamental problems with this approach.
    > > >
    > > > Things that still need to be sorted out:
    > > >
    > > > 1) Since jump_label.h, are included in kernel.h, (indirectly via the
    > > > dynamic_debug.h) the atomic_t definitions could be problematic, since
    > > > atomic.h includes kernel.h indirectly...so we might need some header
    > > > magic.
    > >
    > > Yes, I remember running into that when I did the jump_label_ref stuff,
    > > some head-scratching is in order there.
    > >
    >
    > yes. i suspect this might be the hardest bit of this...

    I remember that atomic_t is defined in types.h now rather than atomic.h.
    Any reason why you should keep including atomic.h from jump_label.h ?

    Thanks,

    Mathieu

    --
    Mathieu Desnoyers
    Operating System Efficiency R&D Consultant
    EfficiOS Inc.
    http://www.efficios.com


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