From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 45F453ACF00; Thu, 18 Jun 2026 08:30:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781771436; cv=none; b=Xlh9JmSMb8wCsXglBzxyRHjK+RPhyUj+HXl1BqDwvhBdkwmQkgkgCEp6fn+Y7PgqEJaxFC3Pg0Vo7Dbes+FzsVnGtK8ji8e9Ud7nsDj1FZ1G+x0pmuY/SyA+Xali+HaZ98+eIs8JbWBxeE61/uHsyvwlKw9ZQ+qaEjaS3ndy0w0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781771436; c=relaxed/simple; bh=BE+AkOT+UhVmsr+Fbbhh+B/l1rTNj1zC2tHJxKWFb0E=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=lJ3UCxYke7GoYvlXTvf8hkaY4xH5i4GGvCfQcnjjujLGD97nkXWMJ9fB5CC0bT5Uaf9XfsidMF08H7jZog9R7ojIcpLOZHHPhOguvEmphnbVGOoEBHPg+FiAkb1Mi0rilZHWXNL3X71hfQqFjNiuBDZT0NjQRD6zdrzhx/pigLA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fK7PnRy1; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fK7PnRy1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6F6F61F000E9; Thu, 18 Jun 2026 08:30:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781771434; bh=nGhbQekJqWwn8AB1BZdGKXVYLktjfCTf6Z1qRB9iehw=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=fK7PnRy1mINc5gLPRbZ/6poyoyt3t0M5bTbyMiyuB+bCopIZKet3C9E0v4PFNnI62 5k+oajs2ANDCtmp8bMremIf/p6d8ZT8sdS9ERHa0Eve379SeQIuOT2M/1DidM9MU/X fu5RQE4Lk+uEm1Z6yIBiCSXZHefqC16Kb53h0AvJ4CCDPCNolrnHtE63hLaVwARE3t qn1kbie8UesGRg8N1K72yF7fpHszX+ZMuNWahliLPf6/CxseOWPKrbV7Cl0s1Qlg2b RNsZWj9wqgLcRcdKgEPI6i5U6pMhz+0bX6xueOpDEWd1VA/0YRdMDVk0rsUJyGrfxg 7QgBmSYhw7E8w== Message-ID: Date: Thu, 18 Jun 2026 10:30:27 +0200 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] mm/lruvec: trace LRU add drains and drain-all requests Content-Language: en-US To: "David Hildenbrand (Arm)" , Shakeel Butt Cc: JP Kobryn , linux-mm@kvack.org, willy@infradead.org, usama.arif@linux.dev, akpm@linux-foundation.org, mhocko@suse.com, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, kasong@tencent.com, qi.zheng@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, chrisl@kernel.org, shikemeng@huaweicloud.com, nphamcs@gmail.com, baoquan.he@linux.dev, youngjun.park@lge.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org References: <20260610195220.12403-1-jp.kobryn@linux.dev> <06122cae-e28b-4ded-a9dd-d380d31c5230@kernel.org> <1136baf3-3967-4202-9eaa-5fd667c235cf@kernel.org> <3149bc84-dd3a-43ba-826e-6364965fdafd@kernel.org> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/18/26 10:21, David Hildenbrand (Arm) wrote: > On 6/17/26 20:18, Vlastimil Babka (SUSE) wrote: >> On 6/17/26 17:03, Shakeel Butt wrote: >>> On Wed, Jun 17, 2026 at 01:11:16PM +0200, David Hildenbrand (Arm) wrote: >>>> >>>> Given that trace events can quickly become stable ABI [1], are we really sure we >>>> want to add this? >>> >>> Yes, I think so as this is useful to get insights into lru cache draining. >>> Trace events being stable or not is secondary IMHO. If in future we rearchitect >>> the lru page handling where there is no cache draining anymore, we can make >>> these a noops. >> >> Yeah and I don't recall ever that a change to a mm tracepoint would ever >> break someone who'd complain and we'd have to revert it. > Really? :) > > Read the context of the link I posted once more. Ah, I see. I've only read the single mail from Steven that referred to the old powertop breakage and didn't notice the context. But I don't think these worries should stop us from adding easily usable tracepoints.