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Date: Mon, 14 Sep 2015 17:09:31 +0530 From: Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com> To: Vladimir Davydov <vdavydov@...allels.com> CC: benh@...nel.crashing.org, paulus@...ba.org, mpe@...erman.id.au, anton@...ba.org, akpm@...ux-foundation.org, nacc@...ux.vnet.ibm.com, gkurz@...ux.vnet.ibm.com, zhong@...ux.vnet.ibm.com, grant.likely@...aro.org, nikunj@...ux.vnet.ibm.com, linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org Subject: Re: [PATCH 1/2] mm: Replace nr_node_ids for loop with for_each_node in list lru On 09/14/2015 02:30 PM, Vladimir Davydov wrote: > Hi, > > On Wed, Sep 09, 2015 at 12:01:46AM +0530, Raghavendra K T wrote: >> The functions used in the patch are in slowpath, which gets called >> whenever alloc_super is called during mounts. >> >> Though this should not make difference for the architectures with >> sequential numa node ids, for the powerpc which can potentially have >> sparse node ids (for e.g., 4 node system having numa ids, 0,1,16,17 >> is common), this patch saves some unnecessary allocations for >> non existing numa nodes. >> >> Even without that saving, perhaps patch makes code more readable. > > Do I understand correctly that node 0 must always be in > node_possible_map? I ask, because we currently test > lru->node[0].memcg_lrus to determine if the list is memcg aware. > Yes, node 0 is always there. So it should not be a problem. >> >> Signed-off-by: Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com> >> --- >> mm/list_lru.c | 23 +++++++++++++++-------- >> 1 file changed, 15 insertions(+), 8 deletions(-) >> >> diff --git a/mm/list_lru.c b/mm/list_lru.c >> index 909eca2..5a97f83 100644 >> --- a/mm/list_lru.c >> +++ b/mm/list_lru.c >> @@ -377,7 +377,7 @@ static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware) >> { >> int i; >> >> - for (i = 0; i < nr_node_ids; i++) { >> + for_each_node(i) { >> if (!memcg_aware) >> lru->node[i].memcg_lrus = NULL; > > So, we don't explicitly initialize memcg_lrus for nodes that are not in > node_possible_map. That's OK, because we allocate lru->node using > kzalloc. However, this partial nullifying in case !memcg_aware looks > confusing IMO. Let's drop it, I mean something like this: Yes, you are right. and we do not have to have memcg_aware check inside for loop too. Will change as per your suggestion and send V2. Thanks for the review. > > static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware) > { > int i; > > if (!memcg_aware) > return 0; > > for_each_node(i) { > if (memcg_init_list_lru_node(&lru->node[i])) > goto fail; > } > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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