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

From: Raghavendra K T
Date: Fri Aug 19 2011 - 02:21:41 EST


On 08/17/2011 06:13 PM, Michal Hocko wrote:
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.

I agree, I could get same MD5 sum only in N N N config case (3rd config).
I am not sure whether we can get same Md5 after lines have been split.
Here is what I tried: static KBUILD_BUILD_TIMESTAMP KBUILD_BUILD_VERSION, initramfs source. strip vmlinux. (could not disable CONFIG_BUG).
I referred to 32nb 64b unification also, did not get much insight from there on same MD5.


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
Yes
8908671 519808 1884160 11312639 ac9dff vmlinux


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.

8878794 517632 1880064 11276490 ac10ca vmlinux before and after


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.
Agree.

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