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 AE0BE1FF7C5; Fri, 25 Sep 2026 07:04:47 +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=1790319888; cv=none; b=ex+22diLHF9ch322PvkVYSfUv9pLDqucFw12gRaXoPgZzp7GwleLjyx8cQ0ITg7Ses47YiswQKMGn4U3gAl9gW0zyoyvPjGAe2c+Lr70REj3Yrfc0XTmY+LLeskrDbLtAjvP/6d1sE1BTjXJQJJZej13lY8SaOKPzKCZu+HgqgE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790319888; c=relaxed/simple; bh=jamQtrSIJs1YQbvuYNiUWI4qI+1n/hJ995IIdIpNYFE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=b7bfj8KRslaOJYiFF9tACcd31JkhgpQTwKG1JWoxu6rJwSIUQfaCFc1kjJWuICuyVI6k5OHpyfE3hfeE7Y5s59jRTpjqZA5mQ3su1miWTIL/AgIg+BFPvTxw+426rpiJHZJJTUCgKTd0/HHWD8U6MhKvSRI7PZclVxsv5beOcJg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=V52F8MgQ; 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="V52F8MgQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7E7A01F00893; Fri, 25 Sep 2026 07:04:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790319887; bh=2R8jdNeSaYTQ16udVa5y7SwjDq151umXysfrxK7mNdI=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=V52F8MgQ20KUBOmKrAhaGUJM9Z4YWg1Tl6VFjhczV6hH8DMfMdkF+KoS4ueEUUerw ufNTZhjdv92yy+ALpgu0sU0ryigCRt8Og+yRwxG8CMzjl3kqHPerkN7EJDEttUEY5A zPDDyqeglEIkcvX32JrWA2CBiX316hug4Efd+nVaRcRhULAgVtAq07dSjFdGD7JycT gXpy91I/RtYYjSx0vWE+RIGsAisvxkTt7IAXideVvb6oC1Qry2G3zsTiRYJdwVXqvD ncqlR+Pt2ptX7HYuxO/EM9smmCXxnDJ/3KarbavB3od8DfYBxV+l6/q8vy6nPzNTMU 89sTcP+vWNSzw== Message-ID: <9f63d60c-913e-4e79-9d28-890dd48ef713@kernel.org> Date: Fri, 25 Sep 2026 09:04:41 +0200 Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [FYI] DAMON and virtio-balloon in DeepSeek's DSec paper To: Lance Yang , sj@kernel.org, mst@redhat.com Cc: damon@lists.linux.dev, linux-mm@kvack.org, virtualization@lists.linux.dev, ryncsn@gmail.com, kunwu.chan@gmail.com, lianux.mm@gmail.com, baohua@kernel.org, xueyuan.chen21@gmail.com References: <20260925054408.10431-1-lance.yang@linux.dev> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/25/26 07:44, Lance Yang wrote: > Hi all, > > I was reading DeepSeek's new DSec paper[1] and found a nice use of DAMON > and virtio-balloon: > > With this kind of workload, an agent may read a file once and never touch > it again, while those pages remain in the guest page cache. Without memory > pressure in the guest, they can stay cached even though the host would > like that memory back ... > > The trick is DAMON + virtio-balloon free-page reporting :) DAMON reclaims Heh, I read "virtio-balloon" and thought "balloon inflation/deflation, what year is it?!". Free-page reporting makes much more sense. > cold file pages from the guest page cache; buddy gets a chance to coalesce > them into reportable blocks, and virtio-balloon passes those blocks to > Firecracker. Firecracker can then drop the host backing with MADV_DONTNEED. When I was at RH we were looking at this issue as well. virtio-pmem was one way of avoiding the page cache in VM entirely. But it has its own limitations. Thanks for sharing! -- Cheers, David