Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753349Ab0BUWRK (ORCPT ); Sun, 21 Feb 2010 17:17:10 -0500 Received: from trinity.develer.com ([83.149.158.210]:34561 "EHLO trinity.develer.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753136Ab0BUWRJ (ORCPT ); Sun, 21 Feb 2010 17:17:09 -0500 Date: Sun, 21 Feb 2010 23:17:01 +0100 From: Andrea Righi To: David Rientjes Cc: Balbir Singh , KAMEZAWA Hiroyuki , Suleiman Souhlal , Vivek Goyal , Andrew Morton , containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] memcg: dirty pages accounting and limiting infrastructure Message-ID: <20100221221700.GA5233@linux> References: <1266765525-30890-1-git-send-email-arighi@develer.com> <1266765525-30890-2-git-send-email-arighi@develer.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4097 Lines: 163 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/