From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-101.freemail.mail.aliyun.com (out30-101.freemail.mail.aliyun.com [115.124.30.101]) (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 BA4C625EFBD for ; Fri, 20 Jun 2025 10:00:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.101 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750413606; cv=none; b=JZ6hPvinWmnXpCoGFokUQOs9BTawaoQPGuHWqiKjBVemN01eZ6EPKmwBrpVJbkMdOaxEqS8hVi5JlmGEiv6vPrOxxvvy3xF7J5AKvHAYcOPZHpyIQUa1zZlcAdKxV1o3Lhut4IMlmDYZV/csJrJLzf5/Sg2KW/N7eW3LbRG3w10= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750413606; c=relaxed/simple; bh=J8v50XXcHs2LqKAUBjBc6/S9CP1OrS9SIRED0TDTwp8=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=ISA0XNcGS9lXERAkbPFkYwiYZ4qjmCxjbem4bm2MngqybkvVdR72h+MJvX2F/jBzcahjjheiMJ4UQ4ekqrfebpYqpCEzKcn7kL5xGWf7KeZSvJbSEajLPunTTFcjiQ2PMMENInizzMS1wAvvmVCyZH6ymCt0WhGFQPcTNvCW04U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=MHtOtQFC; arc=none smtp.client-ip=115.124.30.101 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="MHtOtQFC" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1750413595; h=From:To:Subject:Date:Message-ID:MIME-Version:Content-Type; bh=4cnI0OaEuBfKBwhMYC30kL+gQC7VbBBAf/kqL/GN16A=; b=MHtOtQFCAbRUjsomsb2aMTx5aXehYrCsh124XQREz2TkRczC5oOi0SGOVr5pt/d+MKJudV6MmYK/xL/VfopFQ4gUkt+JJKkXnJOEEg4Rqcz+YTKpGFlIxv/Aj9nkBz22Tl3LgMrBz6MpIxIktuOXcA2mAHriNGUOW5WMbAqlJ9M= Received: from DESKTOP-5N7EMDA(mailfrom:ying.huang@linux.alibaba.com fp:SMTPD_---0WeKSK1H_1750413592 cluster:ay36) by smtp.aliyun-inc.com; Fri, 20 Jun 2025 17:59:53 +0800 From: "Huang, Ying" To: Bharata B Rao Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Jonathan.Cameron@huawei.com, dave.hansen@intel.com, gourry@gourry.net, hannes@cmpxchg.org, mgorman@techsingularity.net, mingo@redhat.com, peterz@infradead.org, raghavendra.kt@amd.com, riel@surriel.com, rientjes@google.com, sj@kernel.org, weixugc@google.com, willy@infradead.org, ziy@nvidia.com, dave@stgolabs.net, nifan.cxl@gmail.com, xuezhengchu@huawei.com, yiannis@zptcorp.com, akpm@linux-foundation.org, david@redhat.com Subject: Re: [RFC PATCH v1 0/4] Kernel thread based async batch migration In-Reply-To: (Bharata B. Rao's message of "Fri, 20 Jun 2025 14:28:33 +0530") References: <20250616133931.206626-1-bharata@amd.com> <87bjqi3ohx.fsf@DESKTOP-5N7EMDA> Date: Fri, 20 Jun 2025 17:59:52 +0800 Message-ID: <87zfe220o7.fsf@DESKTOP-5N7EMDA> User-Agent: Gnus/5.13 (Gnus v5.13) 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=ascii Bharata B Rao writes: > On 20-Jun-25 12:09 PM, Huang, Ying wrote: >> Bharata B Rao writes: >> >> >> I don't think page flag + scanning is a good idea.If the > > If extended page flags is not the ideal location (I chose it in this > version only to get something going quickly), we can look at maintaining > per-pfn allocation for the required hot page metadata separately. > > Or is your concern specifically with scanning? What problems do you > see? > > It is the cost or the possibility of not identifying the migrate-ready > pages in time? Or something else?? We may need to scan a large number of pages to identify a page to promote. This will waste CPU cycles and pollute cache. --- Best Regards, Huang, Ying