Re: [PATCH] use vmalloc for mem_cgroup allocation. v2

From: Li Zefan
Date: Mon Apr 14 2008 - 22:10:49 EST


KAMEZAWA Hiroyuki wrote:
> On ia64, this kmalloc() requires order-4 pages. But this is not
> necessary to be phisically contiguous. (and x86-32, which has
> small vmalloc area, has small mem_cgroup struct.)
>
> For here, vmalloc is better.
>
> Changelog: v1->v2
> - added memset().
>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
>
> Index: mm-2.6.25-rc8-mm2/mm/memcontrol.c
> ===================================================================
> --- mm-2.6.25-rc8-mm2.orig/mm/memcontrol.c
> +++ mm-2.6.25-rc8-mm2/mm/memcontrol.c
> @@ -31,6 +31,7 @@
> #include <linux/spinlock.h>
> #include <linux/fs.h>
> #include <linux/seq_file.h>
> +#include <linux/vmalloc.h>
>
> #include <asm/uaccess.h>
>
> @@ -992,8 +993,10 @@ mem_cgroup_create(struct cgroup_subsys *
> if (unlikely((cont->parent) == NULL)) {
> mem = &init_mem_cgroup;
> page_cgroup_cache = KMEM_CACHE(page_cgroup, SLAB_PANIC);
> - } else
> - mem = kzalloc(sizeof(struct mem_cgroup), GFP_KERNEL);
> + } else {
> + mem = vmalloc(sizeof(struct mem_cgroup));
> + memset(mem, 0, sizeof(*mem));

what if mem == NULL. ;)

> + }
>
> if (mem == NULL)
> return ERR_PTR(-ENOMEM);

So we can move this NULL check to the above else branch, in the if brach,
mem won't be NULL.

> @@ -1011,7 +1014,7 @@ free_out:
> for_each_node_state(node, N_POSSIBLE)
> free_mem_cgroup_per_zone_info(mem, node);
> if (cont->parent != NULL)
> - kfree(mem);
> + vfree(mem);
> return ERR_PTR(-ENOMEM);
> }
>
> @@ -1031,7 +1034,7 @@ static void mem_cgroup_destroy(struct cg
> for_each_node_state(node, N_POSSIBLE)
> free_mem_cgroup_per_zone_info(mem, node);
>
> - kfree(mem_cgroup_from_cont(cont));
> + vfree(mem_cgroup_from_cont(cont));
> }
>
> static int mem_cgroup_populate(struct cgroup_subsys *ss,
>
>
>
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