On Sun, Feb 21, 2010 at 01:28:35PM -0800, David Rientjes wrote:
[snip]
> > +static struct mem_cgroup *get_mem_cgroup_from_page(struct page *page)
> > +{
> > + struct page_cgroup *pc;
> > + struct mem_cgroup *mem = NULL;
> > +
> > + pc = lookup_page_cgroup(page);
> > + if (unlikely(!pc))
> > + return NULL;
> > + lock_page_cgroup(pc);
> > + if (PageCgroupUsed(pc)) {
> > + mem = pc->mem_cgroup;
> > + if (mem)
> > + css_get(&mem->css);
> > + }
> > + unlock_page_cgroup(pc);
> > + return mem;
> > +}
>
> Is it possible to merge this with try_get_mem_cgroup_from_page()?
Agreed.
>
> > +
> > +void mem_cgroup_charge_dirty(struct page *page,
> > + enum zone_stat_item idx, int charge)
> > +{
> > + struct mem_cgroup *mem;
> > + struct mem_cgroup_stat_cpu *cpustat;
> > + unsigned long flags;
> > + int cpu;
> > +
> > + if (mem_cgroup_disabled())
> > + return;
> > + /* Translate the zone_stat_item into a mem_cgroup_stat_index */
> > + switch (idx) {
> > + case NR_FILE_DIRTY:
> > + idx = MEM_CGROUP_STAT_FILE_DIRTY;
> > + break;
> > + case NR_WRITEBACK:
> > + idx = MEM_CGROUP_STAT_WRITEBACK;
> > + break;
> > + case NR_WRITEBACK_TEMP:
> > + idx = MEM_CGROUP_STAT_WRITEBACK_TEMP;
> > + break;
> > + case NR_UNSTABLE_NFS:
> > + idx = MEM_CGROUP_STAT_UNSTABLE_NFS;
> > + break;
> > + default:
> > + return;
>
> WARN()? We don't want to silently leak counters.
Agreed.
>
> > + }
> > + /* Charge the memory cgroup statistics */
> > + mem = get_mem_cgroup_from_page(page);
> > + if (!mem) {
> > + mem = root_mem_cgroup;
> > + css_get(&mem->css);
> > + }
>
> get_mem_cgroup_from_page() should probably handle the root_mem_cgroup case
> and return a reference from it.
Right. But I'd prefer to use try_get_mem_cgroup_from_page() without
changing the behaviour of this function.
>
> > +
> > + local_irq_save(flags);
> > + cpu = get_cpu();
> > + cpustat = &mem->stat.cpustat[cpu];
> > + __mem_cgroup_stat_add_safe(cpustat, idx, charge);
>
> get_cpu()? Preemption is already disabled, just use smp_processor_id().
mmmh... actually, we can just copy the code from
mem_cgroup_charge_statistics(), so local_irq_save/restore are not
necessarily needed and we can just use get_cpu()/put_cpu().
> > + put_cpu();
> > + local_irq_restore(flags);
> > + css_put(&mem->css);
> > +}
> > +
> > static unsigned long mem_cgroup_get_local_zonestat(struct mem_cgroup *mem,
> > enum lru_list idx)
> > {
> > @@ -992,6 +1061,97 @@ static unsigned int get_swappiness(struct mem_cgroup
> > *memcg)
> > return swappiness;
> > }
> >
> > +static unsigned long get_dirty_bytes(struct mem_cgroup *memcg)
> > +{
> > + struct cgroup *cgrp = memcg->css.cgroup;
> > + unsigned long dirty_bytes;
> > +
> > + /* root ? */
> > + if (cgrp->parent == NULL)
> > + return vm_dirty_bytes;
> > +
> > + spin_lock(&memcg->reclaim_param_lock);
> > + dirty_bytes = memcg->dirty_bytes;
> > + spin_unlock(&memcg->reclaim_param_lock);
> > +
> > + return dirty_bytes;
> > +}
> > +
> > +unsigned long mem_cgroup_dirty_bytes(void)
> > +{
> > + struct mem_cgroup *memcg;
> > + unsigned long dirty_bytes;
> > +
> > + if (mem_cgroup_disabled())
> > + return vm_dirty_bytes;
> > +
> > + rcu_read_lock();
> > + memcg = mem_cgroup_from_task(current);
> > + if (memcg == NULL)
> > + dirty_bytes = vm_dirty_bytes;
> > + else
> > + dirty_bytes = get_dirty_bytes(memcg);
> > + rcu_read_unlock();
>
> The rcu_read_lock() isn't protecting anything here.
Right!
>
> > +
> > + return dirty_bytes;
> > +}
> > +
> > +u64 mem_cgroup_page_state(enum memcg_page_stat_item item)
> > +{
> > + struct mem_cgroup *memcg;
> > + struct cgroup *cgrp;
> > + u64 ret = 0;
> > +
> > + if (mem_cgroup_disabled())
> > + return 0;
> > +
> > + rcu_read_lock();
>
> Again, this isn't necessary.
OK. I'll apply your changes to the next version of this patch.
Thanks for reviewing!
-Andrea
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