Message-ID: <5069D3D8.9070805@linux.intel.com>
Date: Mon, 01 Oct 2012 10:33:12 -0700
From: "H. Peter Anvin" <hpa@linux.intel.com>
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To: Andrea Arcangeli <aarcange@redhat.com>
CC: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        Andi Kleen <ak@linux.intel.com>, linux-kernel@vger.kernel.org,
        "Kirill A. Shutemov" <kirill@shutemov.name>,
        Arnd Bergmann <arnd@arndb.de>, Ingo Molnar <mingo@kernel.org>,
        linux-arch@vger.kernel.org
Subject: Re: [PATCH 0/3] Virtual huge zero page
References: <1348875441-19561-1-git-send-email-kirill.shutemov@linux.intel.com> <20120929134811.GC26989@redhat.com> <5069B804.6040902@linux.intel.com> <20121001163118.GC18051@redhat.com> <5069CCF9.7040309@linux.intel.com> <20121001172624.GD18051@redhat.com>
In-Reply-To: <20121001172624.GD18051@redhat.com>
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On 10/01/2012 10:26 AM, Andrea Arcangeli wrote:
> 
>> It is well known that microbenchmarks can be horribly misleading.  What
>> led to Kirill investigating huge zero page in the first place was the
>> fact that some applications/macrobenchmarks benefit, and I think those
>> are the right thing to look at.
> 
> The whole point of the two microbenchmarks was to measure the worst
> cases for both scenarios and I think that was useful. Real life using
> zero pages are going to be somewhere in that range.
> 

... and I think it would be worthwhile to know which effect dominates
(or neither, in which case it doesn't matter).

Overall, I'm okay with either as long as we don't lock down 2 MB when
there isn't a huge zero page in use.

	-hpa

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