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 <[email protected]>
---
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
On Thu, 11 Dec 2008 20:00:45 +0100
Tim Blechmann <[email protected]> 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 <[email protected]>
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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>
> > 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 <[email protected]>
>
> Sorry, memcg's code this function in mmotm kernel is now, following.
> Please give me advice if some more thinking is necessary for RT.
using get_cpu/put_cpu, the preemption is disabled ... so mmotm should
not require any changes. my patch would only be required for an
rt-patch, based on a current kernel version ...
instead of applying my patch, one could also use the specific part of
mmotm for the RT tree ...
tim
> 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();
> }
--
[email protected]
http://tim.klingt.org
Silence is only frightening to people who are compulsively
verbalizing.
William S. Burroughs