From: Christoph Lameter <cl@linux-foundation.org> To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>, "balbir@linux.vnet.ibm.com" <balbir@linux.vnet.ibm.com>, "nishimura@mxp.nes.nec.co.jp" <nishimura@mxp.nes.nec.co.jp>, "akpm@linux-foundation.org" <akpm@linux-foundation.org> Subject: Re: [PATCH 2/2] memcg : rewrite percpu countings with new interfaces Date: Fri, 6 Nov 2009 12:27:50 -0500 (EST) [thread overview] Message-ID: <alpine.DEB.1.10.0911061220410.5187@V090114053VZO-1> (raw) In-Reply-To: <20091106175545.b97ee867.kamezawa.hiroyu@jp.fujitsu.com> On Fri, 6 Nov 2009, KAMEZAWA Hiroyuki wrote: > @@ -370,18 +322,13 @@ mem_cgroup_remove_exceeded(struct mem_cg > static bool mem_cgroup_soft_limit_check(struct mem_cgroup *mem) > { > bool ret = false; > - int cpu; > s64 val; > - struct mem_cgroup_stat_cpu *cpustat; > > - cpu = get_cpu(); > - cpustat = &mem->stat.cpustat[cpu]; > - val = __mem_cgroup_stat_read_local(cpustat, MEMCG_EVENTS); > + val = __this_cpu_read(mem->cpustat->count[MEMCG_EVENTS]); > if (unlikely(val > SOFTLIMIT_EVENTS_THRESH)) { > - __mem_cgroup_stat_reset_safe(cpustat, MEMCG_EVENTS); > + __this_cpu_write(mem->cpustat->count[MEMCG_EVENTS], 0); > ret = true; > } > - put_cpu(); > return ret; If you want to use the __this_cpu_xx versions then you need to manage preempt on your own. You need to keep preempt_disable/enable here because otherwise the per cpu variable zeroed may be on a different cpu than the per cpu variable where you got the value from. > +static s64 mem_cgroup_read_stat(struct mem_cgroup *mem, > + enum mem_cgroup_stat_index idx) > +{ > + struct mem_cgroup_stat_cpu *cstat; > + int cpu; > + s64 ret = 0; > + > + for_each_possible_cpu(cpu) { > + cstat = per_cpu_ptr(mem->cpustat, cpu); > + ret += cstat->count[idx]; > + } == ret += per_cpu(mem->cpustat->cstat->count[idx], cpu) > static void mem_cgroup_swap_statistics(struct mem_cgroup *mem, > 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]; > - __mem_cgroup_stat_add_safe(cpustat, MEMCG_NR_SWAP, val); > - put_cpu(); > + __this_cpu_add(mem->cpustat->count[MEMCG_NR_SWAP], val); > } You do not disable preempt on your own so you have to use this_cpu_add() There is no difference between __this_cpu_add and this_cpu_add on x86 but they will differ on platforms that do not have atomic per cpu instructions. The fallback for this_cpu_add is to protect the add with preempt_disable()/enable. The fallback fro __this_cpu_add is just to rely on the caller to ensure that preempt is disabled somehow. > @@ -495,22 +460,17 @@ static void mem_cgroup_charge_statistics > 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, MEMCG_NR_CACHE, val); > + __this_cpu_add(mem->cpustat->count[MEMCG_NR_CACHE], val); Remove __ > else > - __mem_cgroup_stat_add_safe(cpustat, MEMCG_NR_RSS, val); > + __this_cpu_add(mem->cpustat->count[MEMCG_NR_RSS], val); Remove __ > > if (charge) > - __mem_cgroup_stat_add_safe(cpustat, MEMCG_PGPGIN, 1); > + __this_cpu_inc(mem->cpustat->count[MEMCG_PGPGIN]); Remove __ > else > - __mem_cgroup_stat_add_safe(cpustat, MEMCG_PGPGOUT, 1); > - __mem_cgroup_stat_add_safe(cpustat, MEMCG_EVENTS, 1); > - put_cpu(); > + __this_cpu_inc(mem->cpustat->count[MEMCG_PGPGOUT]); > + __this_cpu_inc(mem->cpustat->count[MEMCG_EVENTS]); Remove __ > - /* > - * Preemption is already disabled, we don't need get_cpu() > - */ > - cpu = smp_processor_id(); > - stat = &mem->stat; > - cpustat = &stat->cpustat[cpu]; > - > - __mem_cgroup_stat_add_safe(cpustat, MEMCG_NR_FILE_MAPPED, val); > + __this_cpu_add(mem->cpustat->count[MEMCG_NR_FILE_MAPPED], val); Remove __ > @@ -1650,16 +1597,11 @@ static int mem_cgroup_move_account(struc > > page = pc->page; > if (page_mapped(page) && !PageAnon(page)) { > - cpu = smp_processor_id(); > /* Update mapped_file data for mem_cgroup "from" */ > - stat = &from->stat; > - cpustat = &stat->cpustat[cpu]; > - __mem_cgroup_stat_add_safe(cpustat, MEMCG_NR_FILE_MAPPED, -1); > + __this_cpu_dec(from->cpustat->count[MEMCG_NR_FILE_MAPPED]); You can keep it here since the context already has preempt disabled it seems.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Lameter <cl@linux-foundation.org> To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>, "balbir@linux.vnet.ibm.com" <balbir@linux.vnet.ibm.com>, "nishimura@mxp.nes.nec.co.jp" <nishimura@mxp.nes.nec.co.jp>, "akpm@linux-foundation.org" <akpm@linux-foundation.org> Subject: Re: [PATCH 2/2] memcg : rewrite percpu countings with new interfaces Date: Fri, 6 Nov 2009 12:27:50 -0500 (EST) [thread overview] Message-ID: <alpine.DEB.1.10.0911061220410.5187@V090114053VZO-1> (raw) In-Reply-To: <20091106175545.b97ee867.kamezawa.hiroyu@jp.fujitsu.com> On Fri, 6 Nov 2009, KAMEZAWA Hiroyuki wrote: > @@ -370,18 +322,13 @@ mem_cgroup_remove_exceeded(struct mem_cg > static bool mem_cgroup_soft_limit_check(struct mem_cgroup *mem) > { > bool ret = false; > - int cpu; > s64 val; > - struct mem_cgroup_stat_cpu *cpustat; > > - cpu = get_cpu(); > - cpustat = &mem->stat.cpustat[cpu]; > - val = __mem_cgroup_stat_read_local(cpustat, MEMCG_EVENTS); > + val = __this_cpu_read(mem->cpustat->count[MEMCG_EVENTS]); > if (unlikely(val > SOFTLIMIT_EVENTS_THRESH)) { > - __mem_cgroup_stat_reset_safe(cpustat, MEMCG_EVENTS); > + __this_cpu_write(mem->cpustat->count[MEMCG_EVENTS], 0); > ret = true; > } > - put_cpu(); > return ret; If you want to use the __this_cpu_xx versions then you need to manage preempt on your own. You need to keep preempt_disable/enable here because otherwise the per cpu variable zeroed may be on a different cpu than the per cpu variable where you got the value from. > +static s64 mem_cgroup_read_stat(struct mem_cgroup *mem, > + enum mem_cgroup_stat_index idx) > +{ > + struct mem_cgroup_stat_cpu *cstat; > + int cpu; > + s64 ret = 0; > + > + for_each_possible_cpu(cpu) { > + cstat = per_cpu_ptr(mem->cpustat, cpu); > + ret += cstat->count[idx]; > + } == ret += per_cpu(mem->cpustat->cstat->count[idx], cpu) > static void mem_cgroup_swap_statistics(struct mem_cgroup *mem, > 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]; > - __mem_cgroup_stat_add_safe(cpustat, MEMCG_NR_SWAP, val); > - put_cpu(); > + __this_cpu_add(mem->cpustat->count[MEMCG_NR_SWAP], val); > } You do not disable preempt on your own so you have to use this_cpu_add() There is no difference between __this_cpu_add and this_cpu_add on x86 but they will differ on platforms that do not have atomic per cpu instructions. The fallback for this_cpu_add is to protect the add with preempt_disable()/enable. The fallback fro __this_cpu_add is just to rely on the caller to ensure that preempt is disabled somehow. > @@ -495,22 +460,17 @@ static void mem_cgroup_charge_statistics > 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, MEMCG_NR_CACHE, val); > + __this_cpu_add(mem->cpustat->count[MEMCG_NR_CACHE], val); Remove __ > else > - __mem_cgroup_stat_add_safe(cpustat, MEMCG_NR_RSS, val); > + __this_cpu_add(mem->cpustat->count[MEMCG_NR_RSS], val); Remove __ > > if (charge) > - __mem_cgroup_stat_add_safe(cpustat, MEMCG_PGPGIN, 1); > + __this_cpu_inc(mem->cpustat->count[MEMCG_PGPGIN]); Remove __ > else > - __mem_cgroup_stat_add_safe(cpustat, MEMCG_PGPGOUT, 1); > - __mem_cgroup_stat_add_safe(cpustat, MEMCG_EVENTS, 1); > - put_cpu(); > + __this_cpu_inc(mem->cpustat->count[MEMCG_PGPGOUT]); > + __this_cpu_inc(mem->cpustat->count[MEMCG_EVENTS]); Remove __ > - /* > - * Preemption is already disabled, we don't need get_cpu() > - */ > - cpu = smp_processor_id(); > - stat = &mem->stat; > - cpustat = &stat->cpustat[cpu]; > - > - __mem_cgroup_stat_add_safe(cpustat, MEMCG_NR_FILE_MAPPED, val); > + __this_cpu_add(mem->cpustat->count[MEMCG_NR_FILE_MAPPED], val); Remove __ > @@ -1650,16 +1597,11 @@ static int mem_cgroup_move_account(struc > > page = pc->page; > if (page_mapped(page) && !PageAnon(page)) { > - cpu = smp_processor_id(); > /* Update mapped_file data for mem_cgroup "from" */ > - stat = &from->stat; > - cpustat = &stat->cpustat[cpu]; > - __mem_cgroup_stat_add_safe(cpustat, MEMCG_NR_FILE_MAPPED, -1); > + __this_cpu_dec(from->cpustat->count[MEMCG_NR_FILE_MAPPED]); You can keep it here since the context already has preempt disabled it seems. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2009-11-06 17:29 UTC|newest] Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top 2009-11-06 8:52 [PATCH 0/2] memcg make use of new percpu implementations KAMEZAWA Hiroyuki 2009-11-06 8:52 ` KAMEZAWA Hiroyuki 2009-11-06 8:54 ` [PATCH 1/2] memcg : rename index to short name KAMEZAWA Hiroyuki 2009-11-06 8:54 ` KAMEZAWA Hiroyuki 2009-11-06 8:55 ` [PATCH 2/2] memcg : rewrite percpu countings with new interfaces KAMEZAWA Hiroyuki 2009-11-06 8:55 ` KAMEZAWA Hiroyuki 2009-11-06 17:27 ` Christoph Lameter [this message] 2009-11-06 17:27 ` Christoph Lameter 2009-11-06 18:44 ` KAMEZAWA Hiroyuki 2009-11-06 18:44 ` KAMEZAWA Hiroyuki 2009-11-09 6:44 ` [PATCH 2/2] memcg : rewrite percpu countings with new interfaces v2 KAMEZAWA Hiroyuki 2009-11-09 6:44 ` KAMEZAWA Hiroyuki 2009-11-09 7:07 ` [PATCH 2/2] memcg : rewrite percpu countings with new interfaces Balbir Singh 2009-11-09 7:07 ` Balbir Singh 2009-11-09 8:36 ` KAMEZAWA Hiroyuki 2009-11-09 8:36 ` KAMEZAWA Hiroyuki 2009-11-09 7:04 ` [PATCH 0/2] memcg make use of new percpu implementations Balbir Singh 2009-11-09 7:04 ` Balbir Singh 2009-11-09 7:34 ` KAMEZAWA Hiroyuki 2009-11-09 7:34 ` KAMEZAWA Hiroyuki
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