From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EDAA7C433E7 for ; Mon, 19 Oct 2020 11:40:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 92E13222B8 for ; Mon, 19 Oct 2020 11:40:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="F1HkXC8C" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728149AbgJSLkP (ORCPT ); Mon, 19 Oct 2020 07:40:15 -0400 Received: from mx2.suse.de ([195.135.220.15]:44484 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726222AbgJSLkP (ORCPT ); Mon, 19 Oct 2020 07:40:15 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1603107613; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=SSs1O1InoOlCF59eFFQsx8VtfWEtNgznhwL4lQxQydU=; b=F1HkXC8CTRjdHRaMQnpslvAIzpzB81yHyVDyrEzXQAj72BQucTwGVouULydotSEQJIR4mC rpP/J1o5etlaR5L6XTTU+io6aumU4xmKVprAouxkrOSFbI3V3V6xI9F0KcIGPvTp9sOG8I LgoTvUk5pScVkMiNAlLBCRV3tVteIDI= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 3A38BAC55; Mon, 19 Oct 2020 11:40:13 +0000 (UTC) Date: Mon, 19 Oct 2020 13:40:11 +0200 From: Michal Hocko To: Xianting Tian Cc: axboe@kernel.dk, raghavendra.kt@linux.vnet.ibm.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] blk-mq: remove the calling of local_memory_node() Message-ID: <20201019114011.GE27114@dhcp22.suse.cz> References: <20201019082047.31113-1-tian.xianting@h3c.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201019082047.31113-1-tian.xianting@h3c.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 19-10-20 16:20:47, Xianting Tian wrote: > We don't need to check whether the node is memoryless numa node before > calling allocator interface. SLUB(and SLAB,SLOB) relies on the page > allocator to pick a node. Page allocator should deal with memoryless > nodes just fine. It has zonelists constructed for each possible nodes. > And it will automatically fall back into a node which is closest to the > requested node. As long as __GFP_THISNODE is not enforced of course. > > The code comments of kmem_cache_alloc_node() of SLAB also showed this: > * Fallback to other node is possible if __GFP_THISNODE is not set. > > blk-mq code doesn't set __GFP_THISNODE, so we can remove the calling > of local_memory_node(). yes, this is indeed the case. I cannot really judge the blg-mq code but it seems to be unnecessary. Maybe there are some subtle details not explained by bffed457160ab though. > Fixes: bffed457160ab ("blk-mq: Avoid memoryless numa node encoded in hctx numa_node") But the existing code is not broken. It just overdoes what needs to be done. So effectively bffed457160ab was not needed. I do not think that Fixes is really necessary. > Signed-off-by: Xianting Tian > --- > block/blk-mq-cpumap.c | 2 +- > block/blk-mq.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/block/blk-mq-cpumap.c b/block/blk-mq-cpumap.c > index 0157f2b34..3db84d319 100644 > --- a/block/blk-mq-cpumap.c > +++ b/block/blk-mq-cpumap.c > @@ -89,7 +89,7 @@ int blk_mq_hw_queue_to_node(struct blk_mq_queue_map *qmap, unsigned int index) > > for_each_possible_cpu(i) { > if (index == qmap->mq_map[i]) > - return local_memory_node(cpu_to_node(i)); > + return cpu_to_node(i); > } > > return NUMA_NO_NODE; > diff --git a/block/blk-mq.c b/block/blk-mq.c > index cdced4aca..48f8366b2 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -2737,7 +2737,7 @@ static void blk_mq_init_cpu_queues(struct request_queue *q, > for (j = 0; j < set->nr_maps; j++) { > hctx = blk_mq_map_queue_type(q, j, i); > if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE) > - hctx->numa_node = local_memory_node(cpu_to_node(i)); > + hctx->numa_node = cpu_to_node(i); > } > } > } > -- > 2.17.1 -- Michal Hocko SUSE Labs