Messages in this thread | | | Date | Fri, 19 Apr 2019 15:03:04 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v4 14/16] locking/rwsem: Guard against making count negative |
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On Fri, Apr 19, 2019 at 02:02:07PM +0200, Peter Zijlstra wrote: > On Fri, Apr 19, 2019 at 12:26:47PM +0200, Peter Zijlstra wrote: > > I thought of a horrible horrible alternative: > > Hurm, that's broken as heck. Let me try again.
So I can't make that scheme work, it all ends up wanting to have cmpxchg().
Do we have a performance comparison somewhere of xadd vs cmpxchg readers? I tried looking in the old threads, but I can't seem to locate it.
We need new instructions :/ Or more clever than I can muster just now.
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