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From: Anshuman Khandual <khandual@linux.vnet.ibm.com>
To: Vlastimil Babka <vbabka@suse.cz>,
	Michal Hocko <mhocko@kernel.org>,
	Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	akpm@linux-foundation.org, mike.kravetz@oracle.com
Subject: Re: [RFC] mm/mremap: Remove redundant checks inside vma_expandable()
Date: Tue, 11 Jul 2017 15:14:27 +0530	[thread overview]
Message-ID: <210533b7-3b29-b6bd-24db-03e0c756a882@linux.vnet.ibm.com> (raw)
In-Reply-To: <4c182da0-6c84-df67-b173-6960fac0544a@suse.cz>

On 07/11/2017 11:56 AM, Vlastimil Babka wrote:
> On 07/11/2017 08:03 AM, Michal Hocko wrote:
>> On Tue 11-07-17 09:58:42, Anshuman Khandual wrote:
>>>> here. This is hardly something that would save many cycles in a
>>>> relatively cold path.
>>> Though I have not done any detailed instruction level measurement,
>>> there is a reduction in real and system amount of time to execute
>>> the test with and without the patch.
>>>
>>> Without the patch
>>>
>>> real	0m2.100s
>>> user	0m0.162s
>>> sys	0m1.937s
>>>
>>> With this patch
>>>
>>> real	0m0.928s
>>> user	0m0.161s
>>> sys	0m0.756s
>> Are you telling me that two if conditions cause more than a second
>> difference? That sounds suspicious.
> It's removing also a call to get_unmapped_area(), AFAICS. That means a
> vma search?

I believe removing this function is responsible for the
increase in speed of the test execution.

WARNING: multiple messages have this Message-ID (diff)
From: Anshuman Khandual <khandual@linux.vnet.ibm.com>
To: Vlastimil Babka <vbabka@suse.cz>,
	Michal Hocko <mhocko@kernel.org>,
	Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	akpm@linux-foundation.org, mike.kravetz@oracle.com
Subject: Re: [RFC] mm/mremap: Remove redundant checks inside vma_expandable()
Date: Tue, 11 Jul 2017 15:14:27 +0530	[thread overview]
Message-ID: <210533b7-3b29-b6bd-24db-03e0c756a882@linux.vnet.ibm.com> (raw)
In-Reply-To: <4c182da0-6c84-df67-b173-6960fac0544a@suse.cz>

On 07/11/2017 11:56 AM, Vlastimil Babka wrote:
> On 07/11/2017 08:03 AM, Michal Hocko wrote:
>> On Tue 11-07-17 09:58:42, Anshuman Khandual wrote:
>>>> here. This is hardly something that would save many cycles in a
>>>> relatively cold path.
>>> Though I have not done any detailed instruction level measurement,
>>> there is a reduction in real and system amount of time to execute
>>> the test with and without the patch.
>>>
>>> Without the patch
>>>
>>> real	0m2.100s
>>> user	0m0.162s
>>> sys	0m1.937s
>>>
>>> With this patch
>>>
>>> real	0m0.928s
>>> user	0m0.161s
>>> sys	0m0.756s
>> Are you telling me that two if conditions cause more than a second
>> difference? That sounds suspicious.
> It's removing also a call to get_unmapped_area(), AFAICS. That means a
> vma search?

I believe removing this function is responsible for the
increase in speed of the test execution.

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  parent reply	other threads:[~2017-07-11  9:45 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-10 11:10 [RFC] mm/mremap: Remove redundant checks inside vma_expandable() Anshuman Khandual
2017-07-10 11:10 ` Anshuman Khandual
2017-07-10 13:49 ` Michal Hocko
2017-07-10 13:49   ` Michal Hocko
2017-07-11  4:28   ` Anshuman Khandual
2017-07-11  4:28     ` Anshuman Khandual
2017-07-11  6:03     ` Michal Hocko
2017-07-11  6:03       ` Michal Hocko
2017-07-11  6:26       ` Vlastimil Babka
2017-07-11  6:26         ` Vlastimil Babka
2017-07-11  6:50         ` Michal Hocko
2017-07-11  6:50           ` Michal Hocko
2017-07-11  6:56           ` Vlastimil Babka
2017-07-11  6:56             ` Vlastimil Babka
2017-07-11  7:16             ` Michal Hocko
2017-07-11  7:16               ` Michal Hocko
2017-07-11  7:22               ` Michal Hocko
2017-07-11  7:22                 ` Michal Hocko
2017-07-11 11:19                 ` Anshuman Khandual
2017-07-11 11:19                   ` Anshuman Khandual
2017-07-11 11:11               ` Anshuman Khandual
2017-07-11 11:11                 ` Anshuman Khandual
2017-07-11 11:08             ` Anshuman Khandual
2017-07-11 11:08               ` Anshuman Khandual
2017-07-11 11:22               ` Michal Hocko
2017-07-11 11:22                 ` Michal Hocko
2017-07-19  6:49                 ` Anshuman Khandual
2017-07-19  6:49                   ` Anshuman Khandual
2017-07-11 11:06           ` Anshuman Khandual
2017-07-11 11:06             ` Anshuman Khandual
2017-07-11  9:44         ` Anshuman Khandual [this message]
2017-07-11  9:44           ` Anshuman Khandual
2017-07-11  4:29   ` Anshuman Khandual
2017-07-11  4:29     ` Anshuman Khandual

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