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SubjectRe: [PATCH] Dynamically allocate struct mem_cgroup_stat_cpu memory
(cc containers@lists.osdl.org)

On Thu, 13 Nov 2008 17:42:01 +0100 Jan Blunck <jblunck@suse.de> wrote:

> When increasing NR_CPUS to 4096 the size of struct mem_cgroup is growing to
> 507904 bytes per instance on x86_64. This patch changes the allocation of
> struct mem_cgroup_stat_cpu to be based on the number of configured CPUs during
> boot time. The init_mem_cgroup still is that huge since it stays statically
> allocated and therefore uses the compile-time maximum.
>
> Signed-off-by: Jan Blunck <jblunck@suse.de>
> ---
> mm/memcontrol.c | 52 +++++++++++++++++++++++++++++++++++++++++++---------
> 1 file changed, 43 insertions(+), 9 deletions(-)
>
> Index: b/mm/memcontrol.c
> ===================================================================
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -59,7 +59,7 @@ struct mem_cgroup_stat_cpu {
> } ____cacheline_aligned_in_smp;
>
> struct mem_cgroup_stat {
> - struct mem_cgroup_stat_cpu cpustat[NR_CPUS];
> + struct mem_cgroup_stat_cpu *cpustat;
> };
>
> /*
> @@ -142,7 +142,10 @@ struct mem_cgroup {
> */
> struct mem_cgroup_stat stat;
> };
> -static struct mem_cgroup init_mem_cgroup;
> +static struct mem_cgroup_stat_cpu init_mem_cgroup_stat_cpu[NR_CPUS];
> +static struct mem_cgroup init_mem_cgroup = {
> + .stat = { .cpustat = init_mem_cgroup_stat_cpu },
> +};
>
> /*
> * We use the lower bit of the page->page_cgroup pointer as a bit spin
> @@ -1097,23 +1100,54 @@ static void free_mem_cgroup_per_zone_inf
> static struct mem_cgroup *mem_cgroup_alloc(void)
> {
> struct mem_cgroup *mem;
> + struct mem_cgroup_stat_cpu *cpustat;
> + size_t statsize = nr_cpu_ids * sizeof(*cpustat);
>
> - if (sizeof(*mem) < PAGE_SIZE)
> - mem = kmalloc(sizeof(*mem), GFP_KERNEL);
> - else
> + if (sizeof(*mem) > PAGE_SIZE) {
> mem = vmalloc(sizeof(*mem));
> -
> - if (mem)
> + if (!mem)
> + goto out;
> memset(mem, 0, sizeof(*mem));
> + } else
> + mem = kzalloc(sizeof(*mem), GFP_KERNEL);
> +
> + if (!mem)
> + goto out;
> +
> + if (statsize > PAGE_SIZE) {
> + cpustat = vmalloc(statsize);
> + if (!cpustat)
> + goto out_mem;
> + memset(cpustat, 0, statsize);
> + } else
> + cpustat = kzalloc(statsize, GFP_KERNEL);
> +
> + if (!cpustat)
> + goto out_mem;
> +
> + mem->stat.cpustat = cpustat;
> return mem;
> +
> +out_mem:
> + if (is_vmalloc_addr(mem))
> + vfree(mem);
> + else
> + kfree(mem);
> +out:
> + return NULL;
> }
>
> static void mem_cgroup_free(struct mem_cgroup *mem)
> {
> - if (sizeof(*mem) < PAGE_SIZE)
> - kfree(mem);
> + if (is_vmalloc_addr(mem->stat.cpustat))
> + vfree(mem->stat.cpustat);
> else
> + kfree(mem->stat.cpustat);
> +
> + if (is_vmalloc_addr(mem))
> vfree(mem);
> + else
> + kfree(mem);
> }
>
>
> --
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