From: Wanpeng Li <liwanp@linux.vnet.ibm.com>
To: Jianguo Wu <wujianguo@huawei.com>
Cc: Jianguo Wu <wujianguo106@gmail.com>,
akpm@linux-foundation.org, aarcange@redhat.com,
kirill.shutemov@linux.intel.com, mgorman@suse.de,
xiaoguangrong@linux.vnet.ibm.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/thp: fix comments in transparent_hugepage_flags
Date: Thu, 5 Sep 2013 15:27:08 +0800 [thread overview]
Message-ID: <20130905072708.GA15294@hacker.(null)> (raw)
In-Reply-To: <522825E4.7080404@huawei.com>
Hi Jianguo,
On Thu, Sep 05, 2013 at 02:34:12PM +0800, Jianguo Wu wrote:
>On 2013/9/5 12:58, Wanpeng Li wrote:
>
>> Hi Jianguo,
>> On Thu, Sep 05, 2013 at 11:54:00AM +0800, Jianguo Wu wrote:
>>> On 2013/9/5 11:37, Wanpeng Li wrote:
>>>
>>>> On Thu, Sep 05, 2013 at 11:04:22AM +0800, Jianguo Wu wrote:
>>>>> Hi Wanpeng,
>>>>>
>>>>> On 2013/9/5 10:11, Wanpeng Li wrote:
>>>>>
>>>>>> Hi Jianguo,
>>>>>> On Wed, Sep 04, 2013 at 09:30:22PM +0800, Jianguo Wu wrote:
>>>>>>> Since commit d39d33c332(thp: enable direct defrag), defrag is enable
>>>>>>> for all transparent hugepage page faults by default, not only in
>>>>>>> MADV_HUGEPAGE regions.
>>>>>>>
>>>>>>> Signed-off-by: Jianguo Wu <wujianguo@huawei.com>
>>>>>>> ---
>>>>>>> mm/huge_memory.c | 6 ++----
>>>>>>> 1 file changed, 2 insertions(+), 4 deletions(-)
>>>>>>>
>>>>>>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>>>>>>> index a92012a..abf047e 100644
>>>>>>> --- a/mm/huge_memory.c
>>>>>>> +++ b/mm/huge_memory.c
>>>>>>> @@ -28,10 +28,8 @@
>>>>>>>
>>>>>>> /*
>>>>>>> * By default transparent hugepage support is enabled for all mappings
>>>>>>
>>>>>> This is also stale. TRANSPARENT_HUGEPAGE_ALWAYS is not configured by default in
>>>>>> order that avoid to risk increase the memory footprint of applications w/o a
>>>>>> guaranteed benefit.
>>>>>>
>>>>>
>>>>> Right, how about this:
>>>>>
>>>>> By default transparent hugepage support is disabled in order that avoid to risk
>>>>
>>>> I don't think it's disabled. TRANSPARENT_HUGEPAGE_MADVISE is configured
>>>> by default.
>>>>
>>>
>>> Hi Wanpeng,
>>>
>>> We have TRANSPARENT_HUGEPAGE and TRANSPARENT_HUGEPAGE_ALWAYS/TRANSPARENT_HUGEPAGE_MADVISE,
>>> TRANSPARENT_HUGEPAGE_ALWAYS or TRANSPARENT_HUGEPAGE_MADVISE is configured only if TRANSPARENT_HUGEPAGE
>>> is configured.
>>>
>>> By default, TRANSPARENT_HUGEPAGE=n, and TRANSPARENT_HUGEPAGE_ALWAYS is configured when TRANSPARENT_HUGEPAGE=y.
>>>
>>> commit 13ece886d9(thp: transparent hugepage config choice):
>>>
>>> config TRANSPARENT_HUGEPAGE
>>> - bool "Transparent Hugepage Support" if EMBEDDED
>>> + bool "Transparent Hugepage Support"
>>> depends on X86 && MMU
>>> - default y
>>>
>>> +choice
>>> + prompt "Transparent Hugepage Support sysfs defaults"
>>> + depends on TRANSPARENT_HUGEPAGE
>>> + default TRANSPARENT_HUGEPAGE_ALWAYS
>>>
>>
>> mmotm tree:
>>
>> grep 'TRANSPARENT_HUGEPAGE' .config
>> CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE=y
>> CONFIG_TRANSPARENT_HUGEPAGE=y
>> # CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS is not set
>> CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y
>>
>> distro:
>>
>> grep 'TRANSPARENT_HUGEPAGE' config-3.8.0-26-generic
>> CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE=y
>> CONFIG_TRANSPARENT_HUGEPAGE=y
>> # CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS is not set
>> CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y
>>
>
>Hi Wanpeng,
>
>I'm a little confused, at mm/Kconfig, TRANSPARENT_HUGEPAGE is not configured by default.
>
>and in x86_64, linus tree:
>
>$make defconfig
>$grep 'TRANSPARENT_HUGEPAGE' .config
>CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE=y
># CONFIG_TRANSPARENT_HUGEPAGE is not set
>
Ah, ok, maybe distro enable them.
Regards,
Wanpeng Li
>Do i misunderstand something herei 1/4 ?
>
>Thanks
>
>>
>>> Thanks,
>>> Jianguo Wu
>>>
>>>> Regards,
>>>> Wanpeng Li
>>>>
>>>>> increase the memory footprint of applications w/o a guaranteed benefit, and
>>>>> khugepaged scans all mappings when transparent hugepage enabled.
>>>>> Defrag is invoked by khugepaged hugepage allocations and by page faults for all
>>>>> hugepage allocations.
>>>>>
>>>>> Thanks,
>>>>> Jianguo Wu
>>>>>
>>>>>> Regards,
>>>>>> Wanpeng Li
>>>>>>
>>>>>>> - * and khugepaged scans all mappings. Defrag is only invoked by
>>>>>>> - * khugepaged hugepage allocations and by page faults inside
>>>>>>> - * MADV_HUGEPAGE regions to avoid the risk of slowing down short lived
>>>>>>> - * allocations.
>>>>>>> + * and khugepaged scans all mappings. Defrag is invoked by khugepaged
>>>>>>> + * hugepage allocations and by page faults for all hugepage allocations.
>>>>>>> */
>>>>>>> unsigned long transparent_hugepage_flags __read_mostly =
>>>>>>> #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
>>>>>>> --
>>>>>>> 1.8.1.2
>>>>>>>
>>>>>>> --
>>>>>>> To unsubscribe, send a message with 'unsubscribe linux-mm' in
>>>>>>> the body to majordomo@kvack.org. For more info on Linux MM,
>>>>>>> see: http://www.linux-mm.org/ .
>>>>>>> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>>>>>>
>>>>>> --
>>>>>> To unsubscribe, send a message with 'unsubscribe linux-mm' in
>>>>>> the body to majordomo@kvack.org. For more info on Linux MM,
>>>>>> see: http://www.linux-mm.org/ .
>>>>>> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>> .
>>>>
>>>
>>>
>>
>> --
>> To unsubscribe, send a message with 'unsubscribe linux-mm' in
>> the body to majordomo@kvack.org. For more info on Linux MM,
>> see: http://www.linux-mm.org/ .
>> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>>
>>
>
>
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
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Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2013-09-05 7:27 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-04 13:30 [PATCH] mm/thp: fix comments in transparent_hugepage_flags Jianguo Wu
2013-09-05 2:11 ` Wanpeng Li
2013-09-05 2:11 ` Wanpeng Li
[not found] ` <5227e870.ab42320a.62d4.3d12SMTPIN_ADDED_BROKEN@mx.google.com>
2013-09-05 3:04 ` Jianguo Wu
2013-09-05 3:37 ` Wanpeng Li
2013-09-05 3:54 ` Jianguo Wu
2013-09-05 4:58 ` Wanpeng Li
2013-09-05 4:58 ` Wanpeng Li
[not found] ` <52280f92.e72b320a.2501.6de1SMTPIN_ADDED_BROKEN@mx.google.com>
2013-09-05 6:34 ` Jianguo Wu
2013-09-05 7:27 ` Wanpeng Li [this message]
2013-09-05 7:27 ` Wanpeng Li
2013-09-05 3:37 ` Wanpeng Li
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