On Fri, Jan 21, 2011 at 03:41:41PM +0900, KAMEZAWA Hiroyuki wrote:
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
>
> Current memory cgroup's code tends to assume page_size == PAGE_SIZE
> but THP does HPAGE_SIZE charge.
>
> This is one of fixes for supporing THP. This modifies
> mem_cgroup_check_under_limit to take page_size into account.
>
> Total fixes for do_charge()/reclaim memory will follow this patch.
>
> TODO: By this reclaim function can get page_size as argument.
> So...there may be something should be improvoed.
>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> ---
> include/linux/res_counter.h | 11 +++++++++++
> mm/memcontrol.c | 27 ++++++++++++++-------------
> 2 files changed, 25 insertions(+), 13 deletions(-)
>
> Index: mmotm-0107/include/linux/res_counter.h
> ===================================================================
> --- mmotm-0107.orig/include/linux/res_counter.h
> +++ mmotm-0107/include/linux/res_counter.h
> @@ -182,6 +182,17 @@ static inline bool res_counter_check_und
> return ret;
> }
>
> +static inline s64 res_counter_check_margin(struct res_counter *cnt)
> +{
> + s64 ret;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&cnt->lock, flags);
> + ret = cnt->limit - cnt->usage;
> + spin_unlock_irqrestore(&cnt->lock, flags);
> + return ret;
> +}
> +
> static inline bool res_counter_check_under_soft_limit(struct res_counter *cnt)
> {
> bool ret;
> Index: mmotm-0107/mm/memcontrol.c
> ===================================================================
> --- mmotm-0107.orig/mm/memcontrol.c
> +++ mmotm-0107/mm/memcontrol.c
> @@ -1099,14 +1099,14 @@ unsigned long mem_cgroup_isolate_pages(u
> #define mem_cgroup_from_res_counter(counter, member) \
> container_of(counter, struct mem_cgroup, member)
>
> -static bool mem_cgroup_check_under_limit(struct mem_cgroup *mem)
> +static bool mem_cgroup_check_under_limit(struct mem_cgroup *mem, int page_size)
> {
> if (do_swap_account) {
> - if (res_counter_check_under_limit(&mem->res) &&
> - res_counter_check_under_limit(&mem->memsw))
> + if (res_counter_check_margin(&mem->res) >= page_size &&
> + res_counter_check_margin(&mem->memsw) >= page_size)
> return true;
> } else
> - if (res_counter_check_under_limit(&mem->res))
> + if (res_counter_check_margin(&mem->res) >= page_size)
> return true;
> return false;
> }
> @@ -1367,7 +1367,8 @@ mem_cgroup_select_victim(struct mem_cgro
> static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
> struct zone *zone,
> gfp_t gfp_mask,
> - unsigned long reclaim_options)
> + unsigned long reclaim_options,
> + int page_size)
> {
> struct mem_cgroup *victim;
> int ret, total = 0;
> @@ -1434,7 +1435,7 @@ static int mem_cgroup_hierarchical_recla
> if (check_soft) {
> if (res_counter_check_under_soft_limit(&root_mem->res))
> return total;
> - } else if (mem_cgroup_check_under_limit(root_mem))
> + } else if (mem_cgroup_check_under_limit(root_mem, page_size))
> return 1 + total;
> }
> return total;
> @@ -1844,7 +1845,7 @@ static int __mem_cgroup_do_charge(struct
> return CHARGE_WOULDBLOCK;
>
> ret = mem_cgroup_hierarchical_reclaim(mem_over_limit, NULL,
> - gfp_mask, flags);
> + gfp_mask, flags, csize);
> /*
> * try_to_free_mem_cgroup_pages() might not give us a full
> * picture of reclaim. Some pages are reclaimed and might be
> @@ -1852,7 +1853,7 @@ static int __mem_cgroup_do_charge(struct
> * Check the limit again to see if the reclaim reduced the
> * current usage of the cgroup before giving up
> */
> - if (ret || mem_cgroup_check_under_limit(mem_over_limit))
> + if (ret || mem_cgroup_check_under_limit(mem_over_limit, csize))
> return CHARGE_RETRY;
This is the only site that is really involved with THP. But you need
to touch every site because you change mem_cgroup_check_under_limit()
instead of adding a new function.
I would suggest just adding another function for checking available
space explicitely and only changing this single call site to use it.
Just ignore the return value of mem_cgroup_hierarchical_reclaim() and
check for enough space unconditionally.
Everybody else is happy with PAGE_SIZE pages.
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