From: Punit Agrawal <punit.agrawal@arm.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Mike Kravetz <mike.kravetz@oracle.com>,
linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Tyler Baicar <tbaicar@codeaurora.org>
Subject: Re: [RFC PATCH 0/2] Add hstate parameter to huge_pte_offset()
Date: Fri, 24 Mar 2017 11:23:08 +0000 [thread overview]
Message-ID: <87efxmhqar.fsf@e105922-lin.cambridge.arm.com> (raw)
In-Reply-To: <20170324103709.253qw6pyjaq5wrgb@node.shutemov.name> (Kirill A. Shutemov's message of "Fri, 24 Mar 2017 13:37:09 +0300")
"Kirill A. Shutemov" <kirill@shutemov.name> writes:
> On Thu, Mar 23, 2017 at 01:55:27PM -0700, Mike Kravetz wrote:
>> On 03/23/2017 05:58 AM, Punit Agrawal wrote:
>> > On architectures that support hugepages composed of contiguous pte as
>> > well as block entries at the same level in the page table,
>> > huge_pte_offset() is not able to determine the right offset to return
>> > when it encounters a swap entry (which is used to mark poisoned as
>> > well as migrated pages in the page table).
>> >
>> > huge_pte_offset() needs to know the size of the hugepage at the
>> > requested address to determine the offset to return - the current
>> > entry or the first entry of a set of contiguous hugepages. This came
>> > up while enabling support for memory failure handling on arm64[0].
>> >
>> > Patch 1 adds a hstate parameter to huge_pte_offset() to provide
>> > additional information about the target address. It also updates the
>> > signatures (and usage) of huge_pte_offset() for architectures that
>> > override the generic implementation. This patch has been compile
>> > tested on ia64 and x86.
>>
>> I haven't looked at the performance implications of making huge_pte_offset
>> just a little slower. But, I think you can get hstate from the parameters
>> passed today.
>>
>> vma = find_vma(mm, addr);
>> h = hstate_vma(vma);
>
> It's better to avoid find_vma() in fast(?) path if possible. So passing it
> down is probably better.
Also most call sites of huge_pte_offset() already have the hstate (or
the vma) readily available. So adding overhead feels unnecessary.
I agree that merging the patch will need some co-ordination but lets at
the least give it a shot.
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prev parent reply other threads:[~2017-03-24 11:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-23 12:58 Punit Agrawal
2017-03-23 12:58 ` [RFC PATCH 1/2] mm/hugetlb.c: add " Punit Agrawal
2017-03-23 12:58 ` [RFC PATCH 2/2] arm64: hugetlbpages: Correctly handle swap entries in huge_pte_offset() Punit Agrawal
2017-03-23 20:55 ` [RFC PATCH 0/2] Add hstate parameter to huge_pte_offset() Mike Kravetz
2017-03-24 10:37 ` Kirill A. Shutemov
2017-03-24 11:23 ` Punit Agrawal [this message]
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