From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: David Gibson <dwg@au1.ibm.com>
Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org,
paulus@samba.org,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Subject: Re: [PATCH -V7 02/10] powerpc/THP: Implement transparent hugepages for ppc64
Date: Fri, 03 May 2013 18:19:03 +1000 [thread overview]
Message-ID: <1367569143.4389.56.camel@pasglop> (raw)
In-Reply-To: <20130503045201.GO13041@truffula.fritz.box>
On Fri, 2013-05-03 at 14:52 +1000, David Gibson wrote:
> Here, specifically, the fact that PAGE_BUSY is in PAGE_THP_HPTEFLAGS
> is likely to be bad. If the page is busy, it's in the middle of
> update so can't stably be considered the same as anything.
_PAGE_BUSY is more like a read lock. It means it's being hashed, so what
is not stable is _PAGE_HASHPTE, slot index, _ACCESSED and _DIRTY. The
rest is stable and usually is what pmd_same looks at (though I have a
small doubt vs. _ACCESSED and _DIRTY but at least x86 doesn't care since
they are updated by HW).
Cheers,
Ben.
WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: David Gibson <dwg@au1.ibm.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
paulus@samba.org, linux-mm@kvack.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH -V7 02/10] powerpc/THP: Implement transparent hugepages for ppc64
Date: Fri, 03 May 2013 18:19:03 +1000 [thread overview]
Message-ID: <1367569143.4389.56.camel@pasglop> (raw)
In-Reply-To: <20130503045201.GO13041@truffula.fritz.box>
On Fri, 2013-05-03 at 14:52 +1000, David Gibson wrote:
> Here, specifically, the fact that PAGE_BUSY is in PAGE_THP_HPTEFLAGS
> is likely to be bad. If the page is busy, it's in the middle of
> update so can't stably be considered the same as anything.
_PAGE_BUSY is more like a read lock. It means it's being hashed, so what
is not stable is _PAGE_HASHPTE, slot index, _ACCESSED and _DIRTY. The
rest is stable and usually is what pmd_same looks at (though I have a
small doubt vs. _ACCESSED and _DIRTY but at least x86 doesn't care since
they are updated by HW).
Cheers,
Ben.
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next prev parent reply other threads:[~2013-05-03 8:19 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-28 19:51 [PATCH -V7 00/10] THP support for PPC64 (Patchset 2) Aneesh Kumar K.V
2013-04-28 19:51 ` Aneesh Kumar K.V
2013-04-28 19:51 ` [PATCH -V7 01/10] powerpc/THP: Double the PMD table size for THP Aneesh Kumar K.V
2013-04-28 19:51 ` Aneesh Kumar K.V
2013-05-03 3:21 ` David Gibson
2013-05-03 3:21 ` David Gibson
2013-04-28 19:51 ` [PATCH -V7 02/10] powerpc/THP: Implement transparent hugepages for ppc64 Aneesh Kumar K.V
2013-04-28 19:51 ` Aneesh Kumar K.V
2013-05-03 4:52 ` David Gibson
2013-05-03 4:52 ` David Gibson
2013-05-03 8:19 ` Benjamin Herrenschmidt [this message]
2013-05-03 8:19 ` Benjamin Herrenschmidt
2013-05-03 11:54 ` David Gibson
2013-05-03 11:54 ` David Gibson
2013-05-03 13:00 ` Benjamin Herrenschmidt
2013-05-03 13:00 ` Benjamin Herrenschmidt
2013-05-03 18:54 ` Aneesh Kumar K.V
2013-05-03 18:54 ` Aneesh Kumar K.V
2013-05-04 19:14 ` Aneesh Kumar K.V
2013-05-04 19:14 ` Aneesh Kumar K.V
2013-05-04 21:39 ` Benjamin Herrenschmidt
2013-05-04 21:39 ` Benjamin Herrenschmidt
2013-05-06 1:28 ` David Gibson
2013-05-06 1:28 ` David Gibson
2013-04-28 19:51 ` [PATCH -V7 03/10] powerpc: move find_linux_pte_or_hugepte and gup_hugepte to common code Aneesh Kumar K.V
2013-04-28 19:51 ` Aneesh Kumar K.V
2013-04-28 19:51 ` [PATCH -V7 04/10] powerpc: Update find_linux_pte_or_hugepte to handle transparent hugepages Aneesh Kumar K.V
2013-04-28 19:51 ` Aneesh Kumar K.V
2013-05-03 4:53 ` David Gibson
2013-05-03 4:53 ` David Gibson
2013-05-03 18:58 ` Aneesh Kumar K.V
2013-05-03 18:58 ` Aneesh Kumar K.V
2013-05-04 6:28 ` David Gibson
2013-05-04 6:28 ` David Gibson
2013-04-28 19:51 ` [PATCH -V7 05/10] powerpc: Replace find_linux_pte with find_linux_pte_or_hugepte Aneesh Kumar K.V
2013-04-28 19:51 ` Aneesh Kumar K.V
2013-05-03 4:56 ` David Gibson
2013-05-03 4:56 ` David Gibson
2013-04-28 19:51 ` [PATCH -V7 06/10] powerpc: Update gup_pmd_range to handle transparent hugepages Aneesh Kumar K.V
2013-04-28 19:51 ` Aneesh Kumar K.V
2013-05-03 4:57 ` David Gibson
2013-05-03 4:57 ` David Gibson
2013-04-28 19:51 ` [PATCH -V7 07/10] powerpc/THP: Add code to handle HPTE faults for large pages Aneesh Kumar K.V
2013-04-28 19:51 ` Aneesh Kumar K.V
2013-05-03 5:13 ` David Gibson
2013-05-03 5:13 ` David Gibson
2013-04-28 19:51 ` [PATCH -V7 08/10] powerpc/THP: Enable THP on PPC64 Aneesh Kumar K.V
2013-04-28 19:51 ` Aneesh Kumar K.V
2013-05-03 5:15 ` David Gibson
2013-05-03 5:15 ` David Gibson
2013-05-03 18:49 ` Aneesh Kumar K.V
2013-05-03 18:49 ` Aneesh Kumar K.V
2013-05-05 8:59 ` David Gibson
2013-05-05 8:59 ` David Gibson
2013-04-28 19:51 ` [PATCH -V7 09/10] powerpc: Optimize hugepage invalidate Aneesh Kumar K.V
2013-04-28 19:51 ` Aneesh Kumar K.V
2013-05-03 5:28 ` David Gibson
2013-05-03 5:28 ` David Gibson
2013-05-03 19:05 ` Aneesh Kumar K.V
2013-05-03 19:05 ` Aneesh Kumar K.V
2013-05-03 21:54 ` Benjamin Herrenschmidt
2013-05-03 21:54 ` Benjamin Herrenschmidt
2013-04-28 19:51 ` [PATCH -V7 10/10] powerpc: disable assert_pte_locked Aneesh Kumar K.V
2013-04-28 19:51 ` Aneesh Kumar K.V
2013-05-03 5:30 ` David Gibson
2013-05-03 5:30 ` David Gibson
2013-05-03 19:07 ` Aneesh Kumar K.V
2013-05-03 19:07 ` Aneesh Kumar K.V
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