linux-kernel - Re: [PATCH V2 1/1][cleanup] memcg: renaming of mem variable to memcg

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Date:	Wed, 17 Aug 2011 14:43:40 +0200
From:	Michal Hocko <mhocko@...e.cz>
To:	Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
Cc:	Arend van Spriel <arend@...adcom.com>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	"David S. Miller" <davem@...emloft.net>,
	"nishimura@....nes.nec.co.jp" <nishimura@....nes.nec.co.jp>,
	Balbir Singh <bsingharora@...il.com>,
	"John W. Linville" <linville@...driver.com>,
	Mauro Carvalho Chehab <mchehab@...hat.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ying Han <yinghan@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	"Nikunj A. Dadhania" <nikunj@...ux.vnet.ibm.com>,
	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
	Ciju Rajan K <ciju@...ux.vnet.ibm.com>,
	Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>
Subject: Re: [PATCH V2 1/1][cleanup] memcg: renaming of mem variable to memcg

Sorry for late reply

On Fri 12-08-11 12:36:23, Raghavendra K T wrote:
>  The memcg code sometimes uses "struct mem_cgroup *mem" and sometimes uses
>  "struct mem_cgroup *memcg". This patch renames all mem variables to memcg in
>  source file.
> 
> Testing : Compile tested with following configurations.
> 1) make defconfig ARCH=i386 + CONFIG_CGROUP_MEM_RES_CTLR=y 
> CONFIG_CGROUP_MEM_RES_CTLR_SWAP=y CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED=y
> 
> Binary size Before patch
> ========================
>    text	   data	    bss	    dec	    hex	filename
> 8911169	 520464	1884160	11315793	 acaa51	vmlinux
> 
> Binary Size After patch
> =======================
>    text	   data	    bss	    dec	    hex	filename
> 8911169	 520464	1884160	11315793	 acaa51	vmlinux

It would be much nicer to see unchanged md5sum. I am not sure how much
possible is this with current gcc or whether special command line
parameters have to be used (at least !CONFIG_DEBUG_INFO* is necessary)
but simple variable rename shouldn't be binary visible.
I guess that a similar approach was used during 32b and 64b x86
unification.

> 
> 2) make defconfig ARCH=i386 + CONFIG_CGROUP_MEM_RES_CTLR=y
> CONFIG_CGROUP_MEM_RES_CTLR_SWAP=n CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED=n

I would assume the same testing results as above

> 
> 3) make defconfig ARCH=i386  CONFIG_CGROUP_MEM_RES_CTLR=n
> CONFIG_CGROUP_MEM_RES_CTLR_SWAP=n CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED=n

ditto.

> 
> Other sanity check:
> Bootable configuration on x86 (T60p)  with  CONFIG_CGROUP_MEM_RES_CTLR=y 
> CONFIG_CGROUP_MEM_RES_CTLR_SWAP=y CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED=y
> is tesed with basic mounting of memcgroup, creation of child and parallel fault.
> mkdir -p /cgroup
> mount -t cgroup none /cgroup -o memory
> mkdir /cgroup/0
> echo $$ > /cgroup/0/tasks
> time ./parallel_fault 2 100000 32
> 
> real	0m0.025s
> user	0m0.001s
> sys	0m0.033s

This looks like a random test. I wouldn't add it to the changelog.
-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic
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