From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7A4322FB6 for ; Sun, 4 May 2025 03:03:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746327816; cv=none; b=Kg+lyVFnqxMdel+XONF3hDCJ8BGlx7EVfNvuAvF4P+1ORTVrGEGuFwbHKe3lBDms5+Sf2X6jTwVilwrDXCyG6G9Sj5pqXK/OPtci3m3QMuAplZlpkgA8N2+ZOSj5WMbrjn8I0s6SxulY4Ww3Gin/fTSXeD02oN4RG97gXjIUfug= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746327816; c=relaxed/simple; bh=osY7ZE+fWnahBAFnTA6dw+ECOJbwn2DS8Ko1o49S1Kg=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=n3vlnvKf+vOAHDVH7vxAbuMPCLYTllX+km9ZGPL3/vl02Th0YJxjXVWjF98zAUdUpuj1seDXuTZmM+R3WvavkgJcPV88FygrViNHbPTkq62Wifm9hcQ28sv3Nw9E8G0O1pD3ypSLrA3CwCDtFNEuJqIWlmTcts78f+7M/3J9uDw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=0OwOF5GR; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="0OwOF5GR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 906FCC4CEEB; Sun, 4 May 2025 03:03:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1746327814; bh=osY7ZE+fWnahBAFnTA6dw+ECOJbwn2DS8Ko1o49S1Kg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=0OwOF5GRKu1XM8PCJmtJm7JwwRhQ+5OfsLLDyZ/GlFRiyRAV8do+q5Vwxrmz3T/xa 5ZYDxWowFGupNj8IxGUa0dbSBDxGjyOcbb013O6cd79XD5RrhMX2CdtrnNTCN2fr3e VpiC1xdVqc5nG9LPkG+e6QIebyn0iikxJ2xUoxWA= Date: Sat, 3 May 2025 20:03:34 -0700 From: Andrew Morton To: Oscar Salvador Cc: David Hildenbrand , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vlastimil Babka , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Jonathan Cameron , Rakie Kim Subject: Re: [PATCH v3 0/3] Implement numa node notifier Message-Id: <20250503200334.3f912eeb7ca484bca4eec7fd@linux-foundation.org> In-Reply-To: <20250502083624.49849-1-osalvador@suse.de> References: <20250502083624.49849-1-osalvador@suse.de> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 2 May 2025 10:36:21 +0200 Oscar Salvador wrote: > Memory notifier is a tool that allow consumers to get notified whenever > memory gets onlined or offlined in the system. > Currently, there are 10 consumers of that, but 5 out of those 10 consumers > are only interested in getting notifications when a numa node changes its > memory state. > That means going from memoryless to memory-aware of vice versa. > > Which means that for every {online,offline}_pages operation they get > notified even though the numa node might not have changed its state. Why is this a problem? Is there some bug? Are these notifications so frequent that there are significant inefficiencies here? Further down-thread, Gregory tells us that Dan's patch "seems to fix the underlying problem", but nobody (including Dan) told us about any "problem" at all.