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From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
To: Mike Rapoport <rppt@linux.ibm.com>,
	Pavel Tatashin <pasha.tatashin@gmail.com>
Cc: linux-mm@kvack.org, akpm@linux-foundation.org,
	pavel.tatashin@microsoft.com, mhocko@suse.com,
	dave.jiang@intel.com, linux-kernel@vger.kernel.org,
	willy@infradead.org, davem@davemloft.net,
	yi.z.zhang@linux.intel.com, khalid.aziz@oracle.com,
	rppt@linux.vnet.ibm.com, vbabka@suse.cz,
	sparclinux@vger.kernel.org, dan.j.williams@intel.com,
	ldufour@linux.vnet.ibm.com, mgorman@techsingularity.net,
	mingo@kernel.org, kirill.shutemov@linux.intel.com
Subject: Re: [mm PATCH v3 1/6] mm: Use mm_zero_struct_page from SPARC on all 64b architectures
Date: Wed, 17 Oct 2018 07:52:16 -0700	[thread overview]
Message-ID: <debbf05a-5ab8-3886-f199-0bbdede7f50e@linux.intel.com> (raw)
In-Reply-To: <20181017073045.GA20004@rapoport-lnx>

On 10/17/2018 12:30 AM, Mike Rapoport wrote:
> On Tue, Oct 16, 2018 at 03:01:11PM -0400, Pavel Tatashin wrote:
>>
>>
>> On 10/15/18 4:26 PM, Alexander Duyck wrote:
>>> This change makes it so that we use the same approach that was already in
>>> use on Sparc on all the archtectures that support a 64b long.
>>>
>>> This is mostly motivated by the fact that 8 to 10 store/move instructions
>>> are likely always going to be faster than having to call into a function
>>> that is not specialized for handling page init.
>>>
>>> An added advantage to doing it this way is that the compiler can get away
>>> with combining writes in the __init_single_page call. As a result the
>>> memset call will be reduced to only about 4 write operations, or at least
>>> that is what I am seeing with GCC 6.2 as the flags, LRU poitners, and
>>> count/mapcount seem to be cancelling out at least 4 of the 8 assignments on
>>> my system.
>>>
>>> One change I had to make to the function was to reduce the minimum page
>>> size to 56 to support some powerpc64 configurations.
>>>
>>> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
>>
>>
>> I have tested on Broadcom's Stingray cpu with 48G RAM:
>> __init_single_page() takes 19.30ns / 64-byte struct page
>> Wit the change it takes 17.33ns / 64-byte struct page
>   
> I gave it a run on an OpenPower (S812LC 8348-21C) with Power8 processor and
> with 128G of RAM. My results for 64-byte struct page were:
> 
> before: 4.6788ns
> after: 4.5882ns
> 
> My two cents :)

Thanks. I will add this and Pavel's data to the patch description.

- Alex

  reply	other threads:[~2018-10-17 14:52 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-15 20:26 [mm PATCH v3 0/6] Deferred page init improvements Alexander Duyck
2018-10-15 20:26 ` [mm PATCH v3 1/6] mm: Use mm_zero_struct_page from SPARC on all 64b architectures Alexander Duyck
2018-10-16 19:01   ` Pavel Tatashin
2018-10-17  7:30     ` Mike Rapoport
2018-10-17 14:52       ` Alexander Duyck [this message]
2018-10-17  8:47   ` Michal Hocko
2018-10-17 15:07     ` Alexander Duyck
2018-10-17 15:12       ` Pavel Tatashin
2018-10-17 15:40         ` David Laight
2018-10-17 16:31           ` Alexander Duyck
2018-10-17 17:08             ` Pavel Tatashin
2018-10-17 16:34       ` Michal Hocko
2018-10-15 20:27 ` [mm PATCH v3 2/6] mm: Drop meminit_pfn_in_nid as it is redundant Alexander Duyck
2018-10-16 20:33   ` Pavel Tatashin
2018-10-16 20:49     ` Alexander Duyck
2018-10-16 21:06       ` Pavel Tatashin
2018-10-17  9:04   ` Michal Hocko
2018-10-15 20:27 ` [mm PATCH v3 3/6] mm: Use memblock/zone specific iterator for handling deferred page init Alexander Duyck
2018-10-17  9:11   ` Michal Hocko
2018-10-17 15:17     ` Alexander Duyck
2018-10-17 16:42   ` Mike Rapoport
2018-10-15 20:27 ` [mm PATCH v3 4/6] mm: Move hot-plug specific memory init into separate functions and optimize Alexander Duyck
2018-10-17  9:18   ` Michal Hocko
2018-10-17 15:26     ` Alexander Duyck
2018-10-24 12:36       ` Michal Hocko
2018-10-24 15:08         ` Alexander Duyck
2018-10-24 15:27           ` Michal Hocko
2018-10-24 17:35             ` Alexander Duyck
2018-10-25 12:41               ` Michal Hocko
2018-10-15 20:27 ` [mm PATCH v3 5/6] mm: Use common iterator for deferred_init_pages and deferred_free_pages Alexander Duyck
2018-10-15 20:27 ` [mm PATCH v3 6/6] mm: Add reserved flag setting to set_page_links Alexander Duyck

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