linux-kernel - Re: linux-next: manual merge of the akpm tree with the tip tree

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Date:   Fri, 31 Mar 2017 16:45:46 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Andi Kleen <ak@...ux.intel.com>
Cc:     Stephen Rothwell <sfr@...b.auug.org.au>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
        Linux-Next Mailing List <linux-next@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: linux-next: manual merge of the akpm tree with the tip tree

On Fri, Mar 31, 2017 at 06:54:48AM -0700, Andi Kleen wrote:
> > Argh!
> > 
> > Andrew, please drop that patch. And the x86 out-of-line of __atomic_add_unless().
> 
> Why dropping the second?  Do you have something better?

The try_cmpxchg() patches save about half the text, and do not have the
out-of-line penalty as shown here:

   https://lkml.kernel.org/r/20170322165144.dtidvvbxey7w5pbd@hirez.programming.kicks-ass.net

> On the first there were no 0day regressions, so at least basic performance
> checking has been done.

The first is superseded by much better patches in the scheduler tree.