From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Eric B Munson <emunson@mgebm.net>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Michael J Wolf <mjwolf@us.ibm.com>
Subject: Re: [PATCH 0/5] fix up /proc/$pid/smaps to not split huge pages
Date: Tue, 15 Feb 2011 09:05:25 -0800 [thread overview]
Message-ID: <1297789525.9829.9616.camel@nimitz> (raw)
In-Reply-To: <20110215170152.GF5935@random.random>
On Tue, 2011-02-15 at 18:01 +0100, Andrea Arcangeli wrote:
> > The entire mapping is contained in a THP but the
> > KernelPageSize shows 4kb. For cases where the mapping might
> > have mixed page sizes this may be okay, but for this
> > particular mapping the 4kb page size is wrong.
>
> I'm not sure this is a bug, if the mapping grows it may become 4096k
> but the new pages may be 4k. There's no such thing as a
> vma_mmu_pagesize in terms of hugepages because we support graceful
> fallback and collapse/split on the fly without altering the vma. So I
> think 4k is correct here
How about we bump MMUPageSize for mappings that are _entirely_ huge
pages, but leave it at 4k for mixed mappings? Anyone needing more
detail than that can use the new AnonHugePages count.
KernelPageSize is pretty ambiguous, and we could certainly make the
argument that the kernel is or can still deal with things in 4k blocks.
-- Dave
WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Eric B Munson <emunson@mgebm.net>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Michael J Wolf <mjwolf@us.ibm.com>
Subject: Re: [PATCH 0/5] fix up /proc/$pid/smaps to not split huge pages
Date: Tue, 15 Feb 2011 09:05:25 -0800 [thread overview]
Message-ID: <1297789525.9829.9616.camel@nimitz> (raw)
In-Reply-To: <20110215170152.GF5935@random.random>
On Tue, 2011-02-15 at 18:01 +0100, Andrea Arcangeli wrote:
> > The entire mapping is contained in a THP but the
> > KernelPageSize shows 4kb. For cases where the mapping might
> > have mixed page sizes this may be okay, but for this
> > particular mapping the 4kb page size is wrong.
>
> I'm not sure this is a bug, if the mapping grows it may become 4096k
> but the new pages may be 4k. There's no such thing as a
> vma_mmu_pagesize in terms of hugepages because we support graceful
> fallback and collapse/split on the fly without altering the vma. So I
> think 4k is correct here
How about we bump MMUPageSize for mappings that are _entirely_ huge
pages, but leave it at 4k for mixed mappings? Anyone needing more
detail than that can use the new AnonHugePages count.
KernelPageSize is pretty ambiguous, and we could certainly make the
argument that the kernel is or can still deal with things in 4k blocks.
-- Dave
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next prev parent reply other threads:[~2011-02-15 17:05 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-09 19:54 [PATCH 0/5] fix up /proc/$pid/smaps to not split huge pages Dave Hansen
2011-02-09 19:54 ` Dave Hansen
2011-02-09 19:54 ` [PATCH 1/5] pagewalk: only split huge pages when necessary Dave Hansen
2011-02-09 19:54 ` Dave Hansen
2011-02-10 11:11 ` Mel Gorman
2011-02-10 11:11 ` Mel Gorman
2011-02-10 13:19 ` Andrea Arcangeli
2011-02-10 13:19 ` Andrea Arcangeli
2011-02-10 13:34 ` Mel Gorman
2011-02-10 13:34 ` Mel Gorman
2011-02-09 19:54 ` [PATCH 2/5] break out smaps_pte_entry() from smaps_pte_range() Dave Hansen
2011-02-09 19:54 ` Dave Hansen
2011-02-10 11:15 ` Mel Gorman
2011-02-10 11:15 ` Mel Gorman
2011-02-09 19:54 ` [PATCH 3/5] pass pte size argument in to smaps_pte_entry() Dave Hansen
2011-02-09 19:54 ` Dave Hansen
2011-02-10 11:16 ` Mel Gorman
2011-02-10 11:16 ` Mel Gorman
2011-02-09 19:54 ` [PATCH 4/5] teach smaps_pte_range() about THP pmds Dave Hansen
2011-02-09 19:54 ` Dave Hansen
2011-02-10 11:17 ` Mel Gorman
2011-02-10 11:17 ` Mel Gorman
2011-02-10 18:08 ` Andrea Arcangeli
2011-02-10 18:08 ` Andrea Arcangeli
2011-02-10 19:32 ` Dave Hansen
2011-02-10 19:32 ` Dave Hansen
2011-02-09 19:54 ` [PATCH 5/5] have smaps show transparent huge pages Dave Hansen
2011-02-09 19:54 ` Dave Hansen
2011-02-10 11:20 ` Mel Gorman
2011-02-10 11:20 ` Mel Gorman
2011-02-10 15:01 ` Dave Hansen
2011-02-10 15:01 ` Dave Hansen
2011-02-10 15:09 ` Mel Gorman
2011-02-10 15:09 ` Mel Gorman
2011-02-10 18:09 ` Andrea Arcangeli
2011-02-10 18:09 ` Andrea Arcangeli
2011-02-10 18:20 ` Dave Hansen
2011-02-10 18:20 ` Dave Hansen
2011-02-10 18:39 ` Andrea Arcangeli
2011-02-10 18:39 ` Andrea Arcangeli
2011-02-09 21:24 ` [PATCH 0/5] fix up /proc/$pid/smaps to not split " Andrea Arcangeli
2011-02-09 21:24 ` Andrea Arcangeli
2011-02-20 21:54 ` David Rientjes
2011-02-20 21:54 ` David Rientjes
2011-02-15 16:55 ` Eric B Munson
2011-02-15 17:01 ` Andrea Arcangeli
2011-02-15 17:01 ` Andrea Arcangeli
2011-02-15 17:05 ` Dave Hansen [this message]
2011-02-15 17:05 ` Dave Hansen
2011-02-15 18:00 ` Andrea Arcangeli
2011-02-15 18:00 ` Andrea Arcangeli
2011-02-22 1:53 Dave Hansen
2011-02-22 1:53 ` Dave Hansen
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