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List:       kde-bugs-dist
Subject:    [Bug 301830] MultiThreadedV (mtV): improve Valgrind so that it runs multiple threads in parallel
From:       Philippe Waroquiers <philippe.waroquiers () skynet ! be>
Date:       2012-12-31 17:07:43
Message-ID: bug-301830-17878-SlXJwHnXrh () http ! bugs ! kde ! org/
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https://bugs.kde.org/show_bug.cgi?id=301830

--- Comment #8 from Philippe Waroquiers <philippe.waroquiers@skynet.be> ---
(In reply to comment #6)
> The case of internal counters for statistics or performance monitoring is
> simple to fix.  Change any such counter into a thread-local variable, and
> add a function which sums the values across all threads.  In many cases the
> function does not need a big lock, nor exclusive access.  The counters are
> monotonic, and a sum which may be low by a few counts (a few per thread)
> usually is just fine.

I did a trial to use thread local storage (see attachment 3)
 Not trivial to use as Valgrind cannot use any libc support.
So, it was needed to emulate a part of the needed run-time support
expected by the compiler. This proto was working on some platforms
(x86/amd64/ppc IIRC.
arm looked more tricky. not looked as s390).

But the main problem (the V bits data structure) cannot be solved by TLS.

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