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Fri, 27 Mar 2020 06:21:59 -0700 (PDT) Date: Fri, 27 Mar 2020 13:21:58 +0000 From: Wei Yang To: David Hildenbrand Cc: Wei Yang , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] mm/page_alloc.c: leverage compiler to zero out used_mask Message-ID: <20200327132158.fmnalzjucwt7jk32@master> Reply-To: Wei Yang References: <20200326222445.18781-1-richard.weiyang@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 27, 2020 at 10:32:45AM +0100, David Hildenbrand wrote: >On 26.03.20 23:24, Wei Yang wrote: >> Since we always clear used_mask before getting node order, we can >> leverage compiler to do this instead of at run time. >> >> Signed-off-by: Wei Yang >> --- >> mm/page_alloc.c | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index 0e823bca3f2f..2144b6ceb119 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -5587,14 +5587,13 @@ static void build_zonelists(pg_data_t *pgdat) >> { >> static int node_order[MAX_NUMNODES]; >> int node, load, nr_nodes = 0; >> - nodemask_t used_mask; >> + nodemask_t used_mask = {.bits = {0}}; >> int local_node, prev_node; >> >> /* NUMA-aware ordering of nodes */ >> local_node = pgdat->node_id; >> load = nr_online_nodes; >> prev_node = local_node; >> - nodes_clear(used_mask); >> >> memset(node_order, 0, sizeof(node_order)); >> while ((node = find_next_best_node(local_node, &used_mask)) >= 0) { >> > >t480s: ~/git/linux default_online_type $ git grep "nodemask_t " | grep "=" >arch/x86/mm/numa.c: nodemask_t reserved_nodemask = NODE_MASK_NONE; >arch/x86/mm/numa_emulation.c: nodemask_t physnode_mask = numa_nodes_parsed; >arch/x86/mm/numa_emulation.c: nodemask_t physnode_mask = numa_nodes_parsed; >arch/x86/mm/numa_emulation.c: nodemask_t physnode_mask = numa_nodes_parsed; >drivers/acpi/numa/srat.c:static nodemask_t nodes_found_map = NODE_MASK_NONE; >kernel/irq/affinity.c: nodemask_t nodemsk = NODE_MASK_NONE; >kernel/sched/fair.c: nodemask_t max_group = NODE_MASK_NONE; >mm/memory_hotplug.c: nodemask_t nmask = node_states[N_MEMORY]; >mm/mempolicy.c: nodemask_t mems = cpuset_mems_allowed(current); >mm/mempolicy.c: nodemask_t nodes = NODE_MASK_NONE; >mm/oom_kill.c: const nodemask_t *mask = oc->nodemask; >mm/page_alloc.c:nodemask_t node_states[NR_NODE_STATES] __read_mostly = { >mm/page_alloc.c: nodemask_t saved_node_state = node_states[N_MEMORY]; > >Should this be NODE_MASK_NONE? Thanks, this is gcc extension. Learn something new. I would update this in v2. > >-- >Thanks, > >David / dhildenb -- Wei Yang Help you, Help me