From: Andi Kleen <ak@linux.intel.com>
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, "H. Peter Anvin" <hpa@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
Date: Sat, 29 Sep 2012 07:30:06 -0700 [thread overview]
Message-ID: <20120929143006.GC4110@tassilo.jf.intel.com> (raw)
In-Reply-To: <20120929134811.GC26989@redhat.com>
On Sat, Sep 29, 2012 at 03:48:11PM +0200, Andrea Arcangeli wrote:
> On Sat, Sep 29, 2012 at 02:37:18AM +0300, Kirill A. Shutemov wrote:
> > Cons:
> > - increases TLB pressure;
>
> I generally don't like using 4k tlb entries ever. This only has the
From theory I would also prefer the 2MB huge page.
But some numbers comparing between the two alternatives are definitely
interesting. Numbers are often better than theory.
> There would be a small cache benefit here... but even then some first
> level caches are virtually indexed IIRC (always physically tagged to
Modern x86 doesn't have virtually indexed caches.
-Andi
--
ak@linux.intel.com -- Speaking for myself only
WARNING: multiple messages have this Message-ID (diff)
From: Andi Kleen <ak@linux.intel.com>
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, "H. Peter Anvin" <hpa@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
Date: Sat, 29 Sep 2012 07:30:06 -0700 [thread overview]
Message-ID: <20120929143006.GC4110@tassilo.jf.intel.com> (raw)
In-Reply-To: <20120929134811.GC26989@redhat.com>
On Sat, Sep 29, 2012 at 03:48:11PM +0200, Andrea Arcangeli wrote:
> On Sat, Sep 29, 2012 at 02:37:18AM +0300, Kirill A. Shutemov wrote:
> > Cons:
> > - increases TLB pressure;
>
> I generally don't like using 4k tlb entries ever. This only has the
>From theory I would also prefer the 2MB huge page.
But some numbers comparing between the two alternatives are definitely
interesting. Numbers are often better than theory.
> There would be a small cache benefit here... but even then some first
> level caches are virtually indexed IIRC (always physically tagged to
Modern x86 doesn't have virtually indexed caches.
-Andi
--
ak@linux.intel.com -- Speaking for myself only
--
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WARNING: multiple messages have this Message-ID (diff)
From: Andi Kleen <ak@linux.intel.com>
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, "H. Peter Anvin" <hpa@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
Date: Sat, 29 Sep 2012 07:30:06 -0700 [thread overview]
Message-ID: <20120929143006.GC4110@tassilo.jf.intel.com> (raw)
In-Reply-To: <20120929134811.GC26989@redhat.com>
On Sat, Sep 29, 2012 at 03:48:11PM +0200, Andrea Arcangeli wrote:
> On Sat, Sep 29, 2012 at 02:37:18AM +0300, Kirill A. Shutemov wrote:
> > Cons:
> > - increases TLB pressure;
>
> I generally don't like using 4k tlb entries ever. This only has the
>From theory I would also prefer the 2MB huge page.
But some numbers comparing between the two alternatives are definitely
interesting. Numbers are often better than theory.
> There would be a small cache benefit here... but even then some first
> level caches are virtually indexed IIRC (always physically tagged to
Modern x86 doesn't have virtually indexed caches.
-Andi
--
ak@linux.intel.com -- Speaking for myself only
next prev parent reply other threads:[~2012-09-29 14:30 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-28 23:37 [PATCH 0/3] Virtual huge zero page Kirill A. Shutemov
2012-09-28 23:37 ` Kirill A. Shutemov
2012-09-28 23:37 ` [PATCH 1/3] asm-generic: introduce pmd_special() and pmd_mkspecial() Kirill A. Shutemov
2012-09-28 23:37 ` Kirill A. Shutemov
2012-09-28 23:37 ` [PATCH 2/3] mm, thp: implement virtual huge zero page Kirill A. Shutemov
2012-09-28 23:37 ` Kirill A. Shutemov
2012-09-28 23:37 ` [PATCH 3/3] x86: implement HAVE_PMD_SPECAIL Kirill A. Shutemov
2012-09-28 23:37 ` Kirill A. Shutemov
2012-09-29 13:48 ` [PATCH 0/3] Virtual huge zero page Andrea Arcangeli
2012-09-29 13:48 ` Andrea Arcangeli
2012-09-29 14:30 ` Andi Kleen [this message]
2012-09-29 14:30 ` Andi Kleen
2012-09-29 14:30 ` Andi Kleen
2012-09-29 14:37 ` Andrea Arcangeli
2012-09-29 14:37 ` Andrea Arcangeli
2012-10-01 13:49 ` Kirill A. Shutemov
2012-10-01 16:14 ` Andrea Arcangeli
2012-10-01 16:14 ` Andrea Arcangeli
2012-10-01 17:18 ` Kirill A. Shutemov
2012-10-01 17:18 ` Kirill A. Shutemov
2012-10-01 15:34 ` H. Peter Anvin
2012-10-01 15:34 ` H. Peter Anvin
2012-10-01 16:31 ` Andrea Arcangeli
2012-10-01 16:31 ` Andrea Arcangeli
2012-10-01 17:03 ` H. Peter Anvin
2012-10-01 17:03 ` H. Peter Anvin
2012-10-01 17:15 ` Kirill A. Shutemov
2012-10-01 17:15 ` Kirill A. Shutemov
2012-10-01 18:03 ` Andrea Arcangeli
2012-10-01 18:03 ` Andrea Arcangeli
2012-10-01 17:26 ` Andrea Arcangeli
2012-10-01 17:26 ` Andrea Arcangeli
2012-10-01 17:33 ` H. Peter Anvin
2012-10-01 17:33 ` H. Peter Anvin
2012-10-01 17:36 ` Kirill A. Shutemov
2012-10-01 17:36 ` Kirill A. Shutemov
2012-10-01 17:37 ` H. Peter Anvin
2012-10-01 17:37 ` H. Peter Anvin
2012-10-01 17:44 ` Kirill A. Shutemov
2012-10-01 17:44 ` Kirill A. Shutemov
2012-10-01 17:52 ` H. Peter Anvin
2012-10-01 17:52 ` H. Peter Anvin
2012-10-01 18:56 ` Kirill A. Shutemov
2012-10-01 18:56 ` Kirill A. Shutemov
2012-10-01 18:05 ` Andrea Arcangeli
2012-10-01 18:05 ` Andrea Arcangeli
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