From: "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm <linux-mm@kvack.org>, Zefan Li <lizefan@huawei.com>,
Xinwei Hu <huxinwei@huawei.com>,
Hanjun Guo <guohanjun@huawei.com>
Subject: Re: [PATCH 1/2] mm/memblock: prepare a capability to support memblock near alloc
Date: Thu, 27 Oct 2016 16:23:10 +0800 [thread overview]
Message-ID: <5811B96E.8040800@huawei.com> (raw)
In-Reply-To: <20161027072235.GB6454@dhcp22.suse.cz>
On 2016/10/27 15:22, Michal Hocko wrote:
> On Thu 27-10-16 10:41:24, Leizhen (ThunderTown) wrote:
>>
>>
>> On 2016/10/26 17:31, Michal Hocko wrote:
>>> On Wed 26-10-16 11:10:44, Leizhen (ThunderTown) wrote:
>>>>
>>>>
>>>> On 2016/10/25 21:23, Michal Hocko wrote:
>>>>> On Tue 25-10-16 10:59:17, Zhen Lei wrote:
>>>>>> If HAVE_MEMORYLESS_NODES is selected, and some memoryless numa nodes are
>>>>>> actually exist. The percpu variable areas and numa control blocks of that
>>>>>> memoryless numa nodes need to be allocated from the nearest available
>>>>>> node to improve performance.
>>>>>>
>>>>>> Although memblock_alloc_try_nid and memblock_virt_alloc_try_nid try the
>>>>>> specified nid at the first time, but if that allocation failed it will
>>>>>> directly drop to use NUMA_NO_NODE. This mean any nodes maybe possible at
>>>>>> the second time.
>>>>>>
>>>>>> To compatible the above old scene, I use a marco node_distance_ready to
>>>>>> control it. By default, the marco node_distance_ready is not defined in
>>>>>> any platforms, the above mentioned functions will work as normal as
>>>>>> before. Otherwise, they will try the nearest node first.
>>>>>
>>>>> I am sorry but it is absolutely unclear to me _what_ is the motivation
>>>>> of the patch. Is this a performance optimization, correctness issue or
>>>>> something else? Could you please restate what is the problem, why do you
>>>>> think it has to be fixed at memblock layer and describe what the actual
>>>>> fix is please?
>>>>
>>>> This is a performance optimization.
>>>
>>> Do you have any numbers to back the improvements?
>>
>> I have not collected any performance data, but at least in theory,
>> it's beneficial and harmless, except make code looks a bit
>> urly.
>
> The whole memoryless area is cluttered with hacks because everybody just
> adds pieces here and there to make his particular usecase work IMHO.
> Adding more on top for performance reasons which are even not measured
OK, I will ask my colleagues for help, whether some APPs can be used or not.
> to prove a clear win is a no go. Please step back try to think how this
> could be done with an existing infrastructure we have (some cleanups
OK, I will try to do it. But some infrastructures maybe only restricted in the
theoretical analysis, I don't have the related testing environment, so there is
no way to verify.
> while doing that would be hugely appreciated) and if that is not
> possible then explain why and why it is not feasible to fix that before
I think it will be feasible.
> you start adding a new API.
>
> Thanks!
>
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next prev parent reply other threads:[~2016-10-27 8:26 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-25 2:59 [PATCH 0/2] to support memblock near alloc and memoryless on arm64 Zhen Lei
2016-10-25 2:59 ` [PATCH 1/2] mm/memblock: prepare a capability to support memblock near alloc Zhen Lei
2016-10-25 13:23 ` Michal Hocko
2016-10-26 3:10 ` Leizhen (ThunderTown)
2016-10-26 9:31 ` Michal Hocko
2016-10-27 2:41 ` Leizhen (ThunderTown)
2016-10-27 7:22 ` Michal Hocko
2016-10-27 8:23 ` Leizhen (ThunderTown) [this message]
2016-10-25 2:59 ` [PATCH 2/2] arm64/numa: support HAVE_MEMORYLESS_NODES Zhen Lei
2016-10-26 18:36 ` Will Deacon
2016-10-27 3:54 ` Leizhen (ThunderTown)
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