Date: Fri, 27 May 2016 16:21:11 -0700 From: John Baldwin <jhb@freebsd.org> To: freebsd-current@freebsd.org Cc: Mateusz Guzik <mjguzik@gmail.com> Subject: Re: [PATCH] microoptimize locking primitives by avoiding unnecessary atomic ops Message-ID: <1588845.bSUmdZtqRF@ralph.baldwin.cx> In-Reply-To: <20160527191700.GA23039@dft-labs.eu> References: <20160527191700.GA23039@dft-labs.eu>
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On Friday, May 27, 2016 09:17:01 PM Mateusz Guzik wrote: > Hello there, > > quite some time ago I posted a trivial patch to locking primitives. What > they do is the inline part tries an atomic op and if that fails the > actual function is called, which immediately tries the same op. > > The obvious optimisation checks for the availability of the lock first. > > There concerns about the way it was done previously by relying on > volatile behaving in a specific way. > > Later a simplified version was posted which should not have the concern, > but the thread died. > > I refer you to https://lists.freebsd.org/pipermail/freebsd-current/2015-November/058100.html > for simple benchmark results. > > I would like to get the patch in before 11 freeze. I think this looks fine. Thanks for expanding the previous patch to cover more primitives. -- John Baldwin
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