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 509BA572688; Tue, 8 Sep 2026 15:54:59 +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=1788882901; cv=none; b=OnO4c3a/cgXJC5qYsugJ35Gq4aEl8lDTQjSu8M5tFziJHN0l6bkZHAfM1H50TXzH6Mj0GVcGiXo8+CZ5E2dCAE3yj1sYVJTz7zVoAWyP09RKfATSovKN7tpyon+aS6N6p0uK8sJnIno9Hhh0UaYPEi+2aWNU+sJc78uTGDy6OW8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788882901; c=relaxed/simple; bh=pjkcNDn5KFxGr3G5TviCNOQbg/0IkK4fcvglxKhPONo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=qW47AyLVjJRuQnLReFHMDMAzea4MRwzzarRZrlDzm/AWMWn1Z9lzQbm96CoU5X7BqltlViWdB6wFyxjS/VTUGhbcQPE97pqyLbLjgVAqlLh6W26bTGD8l0i3YLb/1EpiYTqKAGoxrj8K1AZfDHmCK9BRuq4xWc5NTl2kjqPvEm8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jk1wi5nt; 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="jk1wi5nt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AE4AB1F00A3A; Tue, 8 Sep 2026 15:54:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788882899; bh=+LaiAafgtAJeBS+j2Ji6I5vTEBM/3hGCFd1lVdOgJRk=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=jk1wi5ntnDS9w08mvGcPx0/Tng1FRs8OBaQ0uCuMArdSwmO613fP/fiVV8b2MMrGu 3XcaQz6LKP/milwhEwAJABqiicjt/O7NKceozS3oxKfeyPCk22Poa/puMvPVjaTHuV SQMhvm1S0ZLIHiReBjew1P2vsaQwv8KBeLysV905TUV9QCVVSMZshH2vHmDzV8YyHS C3FtJfUXVvMYv5hGYWoPlEshi6eELEi4XXVv9iNxR1bHmw5S52b+o3n/wVxxOp0WG6 V8xwdRhs/Plj7f7XEITSOP90bzJg7XNwFvRORECnTX5/HAj3DETjgtna7WwcsCJXNU i4JRy7WA4Wl0A== Message-ID: <81e0b88b-84d1-4d9b-929d-68d26a6ffdbc@kernel.org> Date: Tue, 8 Sep 2026 17:54:50 +0200 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 01/25] mm/fbatch: remove !CONFIG_SMP special case of folio_activate() Content-Language: en-US To: Hugh Dickins , Andrew Morton Cc: Ackerley Tng , Alexander Viro , Baolin Wang , Barry Song , Binbin Wu , Christian Brauner , Christoph Hellwig , Christoph Lameter , Claudio Imbrenda , David Hildenbrand , JP Kobryn , Jan Kara , Jens Axboe , Johannes Weiner , Kairui Song , Kiryl Shutsemau , Lance Yang , Leonardo Bras , Lorenzo Stoakes , Marcelo Tosatti , Matthew Wilcox , Mel Gorman , Miaohe Lin , Michal Hocko , Minchan Kim , Muchun Song , Oscar Salvador , Peter Zijlstra , Qi Zheng , Rik van Riel , Sebastian Andrzej Siewior , Shakeel Butt , Suren Baghdasaryan , Yang Shi , Yu Zhao , Zach O'Keefe , Zi Yan , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <14a16945-529b-8bc0-ab38-3ea97e54e223@google.com> <3f18ab7d-c12a-d2a3-4d3e-f9908f94f27d@google.com> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/24/26 15:52, Hugh Dickins wrote: > 3.0 commit eb709b0d062e ("mm: batch activate_page() to reduce lock > contention") brought in an ifdef CONFIG_SMP around activate batching: > https://lore.kernel.org/linux-mm/20100805140755.501af8a7.akpm@linux-foundation.org/ > shows a sensitivity to bloat that day, not any incompatibility with UP. > > No other batching here has a UP alternative, and it's a bit confusing: > simplify mm/folio.c a little by removing it now. > > Certainly we can reduce UP bloat (and/or 32-bit bloat) by, say, lowering > FOLIO_BATCH_SIZE from 31: traditionally 16, 14, 15, then raised to 31 by > 6.9 commit 9cecde80aae0 ("mm: increase folio batch size"); or by giving > just the static per-cpu folio batches a type of their own with a smaller > array size on UP (1? or a little batching worthwhile even on UP?). But > not right now, it's orthogonal to this series. > > And I suspect that the old ifdef led to lru_activate being placed last, > whereas it's usually the second most popular fbatch: move it there, to > match cpu_needs_drain() comment "Check these in order of likelihood that > they're not zero". > > Signed-off-by: Hugh Dickins Reviewed-by: Vlastimil Babka (SUSE)