On Thu, 11 Dec 2008 20:00:45 +0100
Tim Blechmann <tim@xxxxxxxxxx> wrote:
> the lru_lock of struct mem_group_per_zone is used to avoid preemption
> during the mem_cgroup_charge_statistics function. this does not work
> correctly, when CONFIG_PREEMPT_RT is enabled.
> therefore, the preemption is disabled using the preempt_disable_rt macro
> in these cases.
>
> Signed-off-by: Tim Blechmann <tim@xxxxxxxxxx>
Sorry, memcg's code this function in mmotm kernel is now, following.
Please give me advice if some more thinking is necessary for RT.
==
static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
struct page_cgroup *pc,
bool charge)
{
int val = (charge)? 1 : -1;
struct mem_cgroup_stat *stat = &mem->stat;
struct mem_cgroup_stat_cpu *cpustat;
int cpu = get_cpu();
cpustat = &stat->cpustat[cpu];
if (PageCgroupCache(pc))
__mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_CACHE, val);
else
__mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_RSS, val);
if (charge)
__mem_cgroup_stat_add_safe(cpustat,
MEM_CGROUP_STAT_PGPGIN_COUNT, 1);
else
__mem_cgroup_stat_add_safe(cpustat,
MEM_CGROUP_STAT_PGPGOUT_COUNT, 1);
put_cpu();
}
==
Regards,
-Kame
> ---
> mm/memcontrol.c | 4 +++-
> 1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 562b94f..70493c4 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -158,7 +158,7 @@ pcg_default_flags[NR_CHARGE_TYPE] = {
> };
>
> /*
> - * Always modified under lru lock. Then, not necessary to preempt_disable()
> + * Always modified under lru lock. Disable preemption with preempt_disable_rt()
> */
> static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
> struct page_cgroup *pc,
> @@ -170,6 +170,7 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
>
> VM_BUG_ON(!irqs_disabled());
>
> + preempt_disable_rt();
> cpustat = &stat->cpustat[smp_processor_id()];
> if (PageCgroupCache(pc))
> __mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_CACHE, val);
> @@ -182,6 +183,7 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
> else
> __mem_cgroup_stat_add_safe(cpustat,
> MEM_CGROUP_STAT_PGPGOUT_COUNT, 1);
> + preempt_enable_rt();
> }
>
> static struct mem_cgroup_per_zone *
> --
> 1.5.6.3
>
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