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Date: Mon, 19 May 2014 19:34:27 -0700 (PDT)
From: Hugh Dickins <hughd@google.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [PATCH V4 0/2] mm: FAULT_AROUND_ORDER patchset performance data
 for powerpc
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Cc: linux-arch@vger.kernel.org, riel@redhat.com,
 Madhavan Srinivasan <maddy@linux.vnet.ibm.com>, dave.hansen@intel.com,
 peterz@infradead.org, x86@kernel.org, linux-kernel@vger.kernel.org,
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 akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org, mingo@kernel.org,
 "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
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On Tue, 20 May 2014, Rusty Russell wrote:
> Hugh Dickins <hughd@google.com> writes:
> >> On Monday 19 May 2014 05:42 AM, Rusty Russell wrote:
> >> > 
> >> > Perhaps we try to generalize from two data points (a slight improvement
> >> > over doing it from 1!), eg:
> >> > 
> >> > /* 4 seems good for 4k-page x86, 0 seems good for 64k page ppc64, so: */
> >> > unsigned int fault_around_order __read_mostly =
> >> >         (16 - PAGE_SHIFT < 0 ? 0 : 16 - PAGE_SHIFT);
> >
> > Rusty's bimodal answer doesn't seem the right starting point to me.
> 
> ?  It's not bimodal, it's graded.  I think you misread?

Yikes, worse than misread, more like I was too rude even to read: sorry!

Hugh