linux-kernel - Re: [Approach #2] [RFC][PATCH] Remove cgroup member from struct page

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Message-ID: <48C7DAF3.1050905@linux.vnet.ibm.com>
Date:	Wed, 10 Sep 2008 07:34:27 -0700
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
CC:	Nick Piggin <nickpiggin@...oo.com.au>,
	Andrew Morton <akpm@...ux-foundation.org>, hugh@...itas.com,
	menage@...gle.com, xemul@...nvz.org, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [Approach #2] [RFC][PATCH] Remove cgroup member from struct page

KAMEZAWA Hiroyuki wrote:
> On Thu, 11 Sep 2008 07:02:44 +1000
> Nick Piggin <nickpiggin@...oo.com.au> wrote:
> 
>> On Wednesday 10 September 2008 21:03, KAMEZAWA Hiroyuki wrote:
>>> On Thu, 11 Sep 2008 06:44:37 +1000
>>>
>>> Nick Piggin <nickpiggin@...oo.com.au> wrote:
>>>> On Wednesday 10 September 2008 11:49, KAMEZAWA Hiroyuki wrote:
>>>>> On Tue, 9 Sep 2008 18:20:48 -0700
>>>>>
>>>>> Balbir Singh <balbir@...ux.vnet.ibm.com> wrote:
>>>>>> * KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> [2008-09-09
>>>>>> 21:30:12]: OK, here is approach #2, it works for me and gives me
>>>>>> really good performance (surpassing even the current memory
>>>>>> controller). I am seeing almost a 7% increase
>>>>> This number is from pre-allcation, maybe.
>>>>> We really do alloc-at-boot all page_cgroup ? This seems a big change.
>>>> It seems really nice to me -- we get the best of both worlds, less
>>>> overhead for those who don't enable the memory controller, and even
>>>> better performance for those who do.
>>> No trobles for me for allocating-all-at-boot policy.
>>> My small concern is
>>>   - wasting page_cgroup for hugepage area.
>>>   - memory hotplug
>> In those cases you still waste the struct page area too. I realise that
>> isn't a good way to justify even more wastage. But I guess it is
>> relatively low. At least, I would think the users would be more happy to
>> get a 7% performance increase for small pages! :)
>>
> I guess the increase mostly because we can completely avoid kmalloc/kfree slow path.
> 

Correct

> Balbir, how about fix our way to allocate-all-at-boot-policy ?
> If you say yes, I think I can help you and I'll find usable part from my garbage.
> 

I am perfectly fine with it, I'll need your expertise to get the
alloc-at-boot-policy correct.

> Following is lockless+remove-page-cgroup-pointer-from-page-struct patch's result.
> 
> rc5-mm1
> ==
> Execl Throughput                           3006.5 lps   (29.8 secs, 3 samples)
> C Compiler Throughput                      1006.7 lpm   (60.0 secs, 3 samples)
> Shell Scripts (1 concurrent)               4863.7 lpm   (60.0 secs, 3 samples)
> Shell Scripts (8 concurrent)                943.7 lpm   (60.0 secs, 3 samples)
> Shell Scripts (16 concurrent)               482.7 lpm   (60.0 secs, 3 samples)
> Dc: sqrt(2) to 99 decimal places         124804.9 lpm   (30.0 secs, 3 samples)
> 
> lockless
> ==
> Execl Throughput                           3035.5 lps   (29.6 secs, 3 samples)
> C Compiler Throughput                      1010.3 lpm   (60.0 secs, 3 samples)
> Shell Scripts (1 concurrent)               4881.0 lpm   (60.0 secs, 3 samples)
> Shell Scripts (8 concurrent)                947.7 lpm   (60.0 secs, 3 samples)
> Shell Scripts (16 concurrent)               485.0 lpm   (60.0 secs, 3 samples)
> Dc: sqrt(2) to 99 decimal places         125437.9 lpm   (30.0 secs, 3 samples)
> 
> lockless + remove page cgroup pointer (my version).
> ==
> Execl Throughput                           3021.1 lps   (29.5 secs, 3 samples)
> C Compiler Throughput                       980.3 lpm   (60.0 secs, 3 samples)
> Shell Scripts (1 concurrent)               4600.0 lpm   (60.0 secs, 3 samples)
> Shell Scripts (8 concurrent)                915.7 lpm   (60.0 secs, 3 samples)
> Shell Scripts (16 concurrent)               468.3 lpm   (60.0 secs, 3 samples)
> Dc: sqrt(2) to 99 decimal places         124909.1 lpm   (30.0 secs, 3 samples)
> 
> Oh,yes. siginificant slow down. I'm glad to kick this patch out to trash box.
> 
> Thanks,
> -Kame
> 


-- 
	Thanks,
	Balbir
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