From: Andrea Arcangeli <aarcange@redhat.com>
To: Dave Hansen <dave@linux.vnet.ibm.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 19:00:26 +0100 [thread overview]
Message-ID: <20110215180026.GH5935@random.random> (raw)
In-Reply-To: <1297789525.9829.9616.camel@nimitz>
On Tue, Feb 15, 2011 at 09:05:25AM -0800, Dave Hansen wrote:
> 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.
Anyone needing the detail that you ask for, already can use the
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.
That's my point. We could bring it to 2m whenever
AnonHugePages==Anonymous, that's a two liner change, but I'm not
really sure if it makes sense or it provides any meaningful info.
That is a slot specific to show hugetlbfs presence and to
differentiate between 2m/1g mappings. I think remaining mutually
exclusive between AnonHugePages > 0 and MMUPageSize >4k is actually
cleaner than a two liner magic returning 2m if AnonHugePages ==
Anonymous.
WARNING: multiple messages have this Message-ID (diff)
From: Andrea Arcangeli <aarcange@redhat.com>
To: Dave Hansen <dave@linux.vnet.ibm.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 19:00:26 +0100 [thread overview]
Message-ID: <20110215180026.GH5935@random.random> (raw)
In-Reply-To: <1297789525.9829.9616.camel@nimitz>
On Tue, Feb 15, 2011 at 09:05:25AM -0800, Dave Hansen wrote:
> 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.
Anyone needing the detail that you ask for, already can use the
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.
That's my point. We could bring it to 2m whenever
AnonHugePages==Anonymous, that's a two liner change, but I'm not
really sure if it makes sense or it provides any meaningful info.
That is a slot specific to show hugetlbfs presence and to
differentiate between 2m/1g mappings. I think remaining mutually
exclusive between AnonHugePages > 0 and MMUPageSize >4k is actually
cleaner than a two liner magic returning 2m if AnonHugePages ==
Anonymous.
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next prev parent reply other threads:[~2011-02-15 18:00 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
2011-02-15 17:05 ` Dave Hansen
2011-02-15 18:00 ` Andrea Arcangeli [this message]
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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