From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f48.google.com (mail-ed1-f48.google.com [209.85.208.48]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B71AE1B81D8 for ; Mon, 9 Sep 2024 14:50:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.48 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725893406; cv=none; b=ZL4CuTIqXJM/MSS7Dr3C73tJnG0eP86U/h0di3XZ8a4BHPKDwABOWHjX2xPZtCSOLlKQcsiiR1A/CMAJjYX5PL/wUvLpUDa/EbZ3t/gwiE1LySOtC2bh1sG/MP0lCmBGZ+tj8vkPzzA+RbzLZJG1AGilxAwTsM/B63Izr+4J7iA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725893406; c=relaxed/simple; bh=VyMYMatbM0ZkxcQ7JH9byFExbaiv76IZbIMr2qViwHw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ZXWH4kDtbJPV/XGGXpA4seo7nOJKtw1apl01X3K1vWcRPOmmpb5+FD688WPjSqLWd4CnHShAOncrEQ3aAG7UxMWR+BfvKoINMmJEtJw9YLCR4P8cFNahSHFHd3nKR7AI2SK1gw4lOeCADvEOsQ/bL77voIb6JqlEaHjr0FMGyNc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=JqrGPKru; arc=none smtp.client-ip=209.85.208.48 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="JqrGPKru" Received: by mail-ed1-f48.google.com with SMTP id 4fb4d7f45d1cf-5c3c30e663fso5087761a12.1 for ; Mon, 09 Sep 2024 07:50:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1725893403; x=1726498203; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=+9v2Ew7hhlLr4kMPvE7YVmpXKAISPQ2qnVJhqFoRzg8=; b=JqrGPKru7XPZ68x5zlbipz+N98DpF3kUcV5OaTg4dObqzxEMjRvIp0BC1scQeP0KvR HI6p8XYn2JV0JlRZZa2duLgqjkkdAbjmzoGlFYEQ0CQXsn551BhKZBZBi8G0OUQZ7i17 BtXX3KCKtgS7nMuMW1IiRRVXTqiQKldzU7W6fTeO+mLz3jw+2WmDkrDGu23MJ0l6VzNh Ep5T3CqR+Wm1U6cOWRrdTg68y4B2FbU56yrs5saE3OUtENZuPciwYzT4mM5yx+Rdt9ro aBXhHf1HJ0g2eGZ1GMLfwP7UIKLblCk6Xk8VLuznqBg0abRKmphj3tIICVv6Gd05jeD9 mBNg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1725893403; x=1726498203; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=+9v2Ew7hhlLr4kMPvE7YVmpXKAISPQ2qnVJhqFoRzg8=; b=Z5MH3Fta9rXjCymv52L+3SyWZDx7P7Rkr50JIflC16H+uQ88hF2BitygaSC1Wai6+7 jN6TNdxdd5fIUM5M+RIg9y9xO7lIKB4ibBqcTyT2/3gcgIQoBuYIKwRokvvNt5lZZ4Vj siXpSNRdKZrGcLaQGngPO7CO05+rYP9ifTPBwFUwAtQx+panqaxRltwTkE5Bf0RlqcGi 9c6I/M2Ml45iavF8ePHQirq/4LiAg0ktBKMlxVyjasTNpZSMeNDUIjwcbI8KOz3D9Ydq 65actpQOY4eZZr9O1GcCdyXsZLBKlexAlDw1IotDnrFzUlKPAKbzVaX7V6vcPfllRI/r OU5Q== X-Forwarded-Encrypted: i=1; AJvYcCWOqzfoQ2tMJdJYa+i6PD1G+DHmVPsF36bQPxN17ubh8HqTIUAb1bBMSIJmoVnUTBvaNY/DQaotRXXVNXE=@vger.kernel.org X-Gm-Message-State: AOJu0YzGCPR1NAN2yhit06h2fpprsMm2pS1SxilTV6p/HYwp1auj0x5a 6GxQfmAOuv4eMV3jgoGW9LDpVm6qOLWneZwZTwWpx41RyD7araTOTMqvg3MRSN8= X-Google-Smtp-Source: AGHT+IHf434hHzqA3na7vHiDZ07v1njm5O6rCFLa56eADhixaf8Z8IRp8g+sM15hDoTHcp+eFRE1lw== X-Received: by 2002:a05:6402:448a:b0:5c2:632e:fad7 with SMTP id 4fb4d7f45d1cf-5c3dc7955famr8352205a12.15.1725893402803; Mon, 09 Sep 2024 07:50:02 -0700 (PDT) Received: from localhost ([193.86.92.181]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5c3ebd8ceccsm3086633a12.91.2024.09.09.07.50.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Sep 2024 07:50:02 -0700 (PDT) Date: Mon, 9 Sep 2024 16:50:02 +0200 From: Michal Hocko To: Hillf Danton Cc: Davidlohr Bueso , yosryahmed@google.com, Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH -next] mm: introduce per-node proactive reclaim interface Message-ID: References: <20240909105157.2663-1-hdanton@sina.com> 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-Disposition: inline In-Reply-To: <20240909105157.2663-1-hdanton@sina.com> On Mon 09-09-24 18:51:57, Hillf Danton wrote: > On Date: Mon, 9 Sep 2024 09:12:03 +0200 Michal Hocko > > On Fri 06-09-24 19:04:19, Hillf Danton wrote: > > > On Thu, 5 Sep 2024 16:29:41 -0700 Davidlohr Bueso > > > > On Fri, 06 Sep 2024, Hillf Danton wrote:\n > > > > >The proactive reclaim on the cmdline looks like waste of cpu cycles before > > > > >the cases where kswapd fails to work are spotted. It is not correct to add > > > > >it because you can type the code. > > > > > > > > Are you against proactive reclaim altogether (ie: memcg) or this patch in > > > > particular, which extends its availability? > > > > > > > The against makes no sense to me because I know your patch is never able to > > > escape standing ovation. > > > > I fail to understand your reasoning. Do you have any actual technical > > arguments why this is a bad idea? > > > > > > The benefits of proactive reclaim are well documented, and the community has > > > > been overall favorable towards it. This operation is not meant to be generally > > > > used, but there are real latency benefits to be had which are completely > > > > unrelated to watermarks. Similarly, we have 'compact' as an alternative to > > > > kcompactd (which was once upon a time part of kswapd). > > > > > > > Because kswapd is responsible for watermark instead of high order pages, > > > compact does not justify proactive reclaim from the begining. > > > > What do you mean? How does keeping a global watermark helps to trigger > > per NUMA node specific aging - e.g. demotion? > > > In addition to the cost of pro/demorion, the percpu pages prevent random aging > from making any sense without memory pressue, because I think it is aging that > rolls out red carpet for multi-gen lru. I am sorry but I do not get what you are trying to say. Can you be _much_more_ specific? -- Michal Hocko SUSE Labs