Messages in this thread | | | Date | Wed, 25 Feb 2009 16:15:33 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [PATCH] use CSS ID in swap_cgroup for saving memory |
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On Wed, 25 Feb 2009 15:09:20 +0800 Li Zefan <lizf@cn.fujitsu.com> wrote:
> > static inline > > -struct mem_cgroup *swap_cgroup_record(swp_entry_t ent, struct mem_cgroup *mem) > > +unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id) > > { > > return NULL; > > return 0; > should be..
> > } > > > > static inline > > -struct mem_cgroup *lookup_swap_cgroup(swp_entry_t ent) > > +unsigned short lookup_swap_cgroup(swp_entry_t ent) > > { > > return NULL; > > return 0; > ok
> > } > > > @@ -1265,12 +1286,20 @@ int mem_cgroup_cache_charge(struct page > > > > if (do_swap_account && !ret && PageSwapCache(page)) { > > swp_entry_t ent = {.val = page_private(page)}; > > + unsigned short id; > > /* avoid double counting */ > > - mem = swap_cgroup_record(ent, NULL); > > + id = swap_cgroup_record(ent, 0); > > + rcu_read_lock(); > > + mem = mem_cgroup_lookup(id); > > if (mem) { > > + /* > > + * Recorded ID can be obsolete. We avoid calling > > + * css_tryget() > > + */ > > res_counter_uncharge(&mem->memsw, PAGE_SIZE); > > mem_cgroup_put(mem); > > } > > + rcu_read_unlock(); > > } > > return ret; > > } > > @@ -1335,13 +1364,21 @@ void mem_cgroup_commit_charge_swapin(str > > */ > > if (do_swap_account && PageSwapCache(page)) { > > swp_entry_t ent = {.val = page_private(page)}; > > + unsigned short id; > > struct mem_cgroup *memcg; > > - memcg = swap_cgroup_record(ent, NULL); > > + > > + id = swap_cgroup_record(ent, 0); > > + rcu_read_lock(); > > + memcg = mem_cgroup_lookup(id); > > if (memcg) { > > + /* > > + * This recorded memcg can be obsolete one. So, avoid > > + * calling css_tryget > > + */ > > res_counter_uncharge(&memcg->memsw, PAGE_SIZE); > > mem_cgroup_put(memcg); > > } > > - > > + rcu_read_unlock(); > > } > > /* add this page(page_cgroup) to the LRU we want. */ > > > > @@ -1462,7 +1499,7 @@ void mem_cgroup_uncharge_swapcache(struc > > MEM_CGROUP_CHARGE_TYPE_SWAPOUT); > > /* record memcg information */ > > if (do_swap_account && memcg) { > > - swap_cgroup_record(ent, memcg); > > + swap_cgroup_record(ent, css_id(&memcg->css)); > > mem_cgroup_get(memcg); > > } > > if (memcg) > > @@ -1477,15 +1514,22 @@ void mem_cgroup_uncharge_swapcache(struc > > void mem_cgroup_uncharge_swap(swp_entry_t ent) > > { > > struct mem_cgroup *memcg; > > + unsigned short id; > > > > if (!do_swap_account) > > return; > > > > - memcg = swap_cgroup_record(ent, NULL); > > + id = swap_cgroup_record(ent, 0); > > + rcu_read_lock(); > > + memcg = mem_cgroup_lookup(id); > > if (memcg) { > > + /* > > + * This memcg can be obsolete one. We avoid calling css_tryget > > + */ > > res_counter_uncharge(&memcg->memsw, PAGE_SIZE); > > mem_cgroup_put(memcg); > > } > > + rcu_read_unlock(); > > can we have a common function for the above 3 pieces of code? >
I don't think it's better. All are under rcu_read_lock() and does "charge" management in diffferent meanings/context. These small pieces of code are worth to be open coded.
> > } > > #endif > > > > Index: mmotm-2.6.29-Feb24/mm/page_cgroup.c > > =================================================================== > > --- mmotm-2.6.29-Feb24.orig/mm/page_cgroup.c > > +++ mmotm-2.6.29-Feb24/mm/page_cgroup.c > > @@ -290,7 +290,7 @@ struct swap_cgroup_ctrl swap_cgroup_ctrl > > * cgroup rather than pointer. > > */ > > this comment should be updated/removed: > > /* > * This 8bytes seems big..maybe we can reduce this when we can use "id" for > * cgroup rather than pointer. > */ > Ah, I missed this.
I'll update and post tomorrow, again if no "don't do that"
Thanks, -Kame
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