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b=yiMVc/ccH+/PxpbGZa9TzNl1kxMg8K43yII2wPHR+9K2AWtRnvhstQJn0yX/5Yz3T h/E//Lh7iS0xDFPR7d8WppgRE6jHyAIpCa5KbWFmrUjLpQk+N8eZQE4jBRFB5XSkVM zVwX9+yzepIwDqIoeeqiHR4M6ZWgAj+stTYsQG+Y= Date: Mon, 19 Feb 2024 17:21:30 -0800 From: Andrew Morton To: Donet Tom Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Aneesh Kumar , Huang Ying , Dave Hansen , Mel Gorman , Ben Widawsky , Feng Tang , Michal Hocko , Andrea Arcangeli , Peter Zijlstra , Ingo Molnar , Rik van Riel , Johannes Weiner , Matthew Wilcox , Mike Kravetz , Vlastimil Babka , Dan Williams , Hugh Dickins , Kefeng Wang , Suren Baghdasaryan Subject: Re: [PATCH 1/3] mm/mempolicy: Use the already fetched local variable Message-Id: <20240219172130.82a16c1ebecbf8ba86a8987d@linux-foundation.org> In-Reply-To: <63a0f7c4-3c3f-4097-9a24-d1e3fc7b6030@linux.ibm.com> References: <9c3f7b743477560d1c5b12b8c111a584a2cc92ee.1708097962.git.donettom@linux.ibm.com> <20240218133851.22c22b55460e866a099be5ce@linux-foundation.org> <63a0f7c4-3c3f-4097-9a24-d1e3fc7b6030@linux.ibm.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 864EA14000A X-Stat-Signature: gd3c67yndehupgc1m6xskr5qbne1myip X-HE-Tag: 1708392093-9478 X-HE-Meta: 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 lDn2ev6C GcAfhTw/hxT9Lf0uSgNuTXrKngVUeQ8DgKEYA8HkM+DMHdD2o25elvEBXAbELU0Q3/utf3IuKR1Qasp02rLgwbof+I7uik9W3yiWtAwGjpugOBD0hG0kFFRmHI5+1IAPVh/x+AeF+oCpEJJ1vnI4bYyPA0BpTnxrKc+qA5Tcs2aCdDKjSyP9Rp1DKAsZxAAjLQ5M8vJW8aLawJ6ihIHLsxqA5qawmoASclh1fsmux3rr5ZtCo634S8pGika6zvd0E0nqL X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 19 Feb 2024 14:04:23 +0530 Donet Tom wrote: > >> --- a/mm/mempolicy.c > >> +++ b/mm/mempolicy.c > >> @@ -2526,7 +2526,7 @@ int mpol_misplaced(struct folio *folio, struct vm_area_struct *vma, > >> if (node_isset(curnid, pol->nodes)) > >> goto out; > >> z = first_zones_zonelist( > >> - node_zonelist(numa_node_id(), GFP_HIGHUSER), > >> + node_zonelist(thisnid, GFP_HIGHUSER), > >> gfp_zone(GFP_HIGHUSER), > >> &pol->nodes); > >> polnid = zone_to_nid(z->zone); > > int thisnid = cpu_to_node(thiscpu); > > > > Is there any dofference between numa_node_id() and > > cpu_to_node(raw_smp_processor_id())? And it it explicable that we're > > using one here and not the other? > > Hi Andrew > > Both numa_node_id() and cpu_to_node(raw_smp_processor_id()) return the current execution node id, > Since the current execution node is already fetched at the beginning (thisnid) we can reuse it instead of getting it again. Sure, but mine was a broader thought: why do we have both? Is one preferable and if so why?