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    SubjectRe: [tip:perf/core] tools/perf: Add required memory barriers

    * Peter Zijlstra <peterz@infradead.org> wrote:

    > On Thu, Nov 07, 2013 at 09:21:22AM +0100, Ingo Molnar wrote:
    > >
    > > * Peter Zijlstra <peterz@infradead.org> wrote:
    > >
    > > > > Requiring the user of a kernel interface to have a deep knowledge of
    > > > > optimizing compilers, barriers, and CPU memory models is just asking
    > > > > for trouble.
    > > >
    > > > It shouldn't be all that hard to put this in a (lgpl) library others can
    > > > link to -- that way you can build it once (using GCC).
    > >
    > > I'd suggest to expose it via a new perf syscall, using vsyscall methods to
    > > not have to enter the kernel for the pure user-space bits. It should also
    > > have a real usecase in tools/perf/ so that it's constantly tested, with
    > > matching 'perf test' entries, etc.
    >
    > Oh man, I've never poked at the entire vsyscall stuff before; let alone
    > done it for ARM, ARM64, PPC64 etc..
    >
    > Keeping it in userspace like we have is so much easier.

    ... and so much more broken in fantastic ways, right? ;-)

    Thanks,

    Ingo


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