2010-11-04 20:28:25

by Jesper Juhl

Subject: [PATCH v2] cgroup: prefer [kv]zalloc[_node] over [kv]malloc+memset in memory controller code.

Hi,

In mem_cgroup_alloc() we currently do either kmalloc() or vmalloc() then
followed by memset() to zero the memory. This can be more efficiently
achieved by using kzalloc() and vzalloc().
There's also one situation where we can use kzalloc_node() - this is
what's new in this version of the patch.

The original patch was:

Acked-by: KAMEZAWA Hiroyuki <[email protected]>
Reviewed-by: Minchan Kim <[email protected]>
Reviewed-by: Wu Fengguang <[email protected]>
Acked-by: Balbir Singh <[email protected]>

Here's version 2. I'd appreciate it if someone could merge it, but I don't
know who that someone would be.


Signed-off-by: Jesper Juhl <[email protected]>
---
memcontrol.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9a99cfa..4f4e676 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4169,13 +4169,11 @@ static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
*/
if (!node_state(node, N_NORMAL_MEMORY))
tmp = -1;
- pn = kmalloc_node(sizeof(*pn), GFP_KERNEL, tmp);
+ pn = kzalloc_node(sizeof(*pn), GFP_KERNEL, tmp);
if (!pn)
return 1;

mem->info.nodeinfo[node] = pn;
- memset(pn, 0, sizeof(*pn));
-
for (zone = 0; zone < MAX_NR_ZONES; zone++) {
mz = &pn->zoneinfo[zone];
for_each_lru(l)
@@ -4199,14 +4197,13 @@ static struct mem_cgroup *mem_cgroup_alloc(void)

/* Can be very big if MAX_NUMNODES is very big */
if (size < PAGE_SIZE)
- mem = kmalloc(size, GFP_KERNEL);
+ mem = kzalloc(size, GFP_KERNEL);
else
- mem = vmalloc(size);
+ mem = vzalloc(size);

if (!mem)
return NULL;

- memset(mem, 0, size);
mem->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
if (!mem->stat) {
if (size < PAGE_SIZE)


--
Jesper Juhl <[email protected]> http://www.chaosbits.net/
Plain text mails only, please http://www.expita.com/nomime.html
Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html

2010-11-04 20:35:09

by Li Zefan

Subject: Re: [PATCH v2] cgroup: prefer [kv]zalloc[_node] over [kv]malloc+memset in memory controller code.

> In mem_cgroup_alloc() we currently do either kmalloc() or vmalloc() then
> followed by memset() to zero the memory. This can be more efficiently
> achieved by using kzalloc() and vzalloc().
> There's also one situation where we can use kzalloc_node() - this is
> what's new in this version of the patch.
>
> The original patch was:
>
> Acked-by: KAMEZAWA Hiroyuki <[email protected]>
> Reviewed-by: Minchan Kim <[email protected]>
> Reviewed-by: Wu Fengguang <[email protected]>
> Acked-by: Balbir Singh <[email protected]>
>
> Here's version 2. I'd appreciate it if someone could merge it, but I don't
> know who that someone would be.
>

Normally it's Andrew Morton.

btw, a better title is: [...] memcgroup: prefer ... over ... memset