From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-119.freemail.mail.aliyun.com (out30-119.freemail.mail.aliyun.com [115.124.30.119]) (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 7E5A4287246 for ; Fri, 26 Dec 2025 06:08:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.119 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766729297; cv=none; b=KVpNchSbk3uz36tZzXrO9m3/ceg98mxzOkIw5ZGmEIVRYqf64Db4GcY+PvSx87FeG8QM8RjKORg9TjYSu2D+s9amlLOfa6bTdPcxTLY4mlAj73xpdiYQbRZ6+KoHUnnNhg9QYSR3ZvlDY4+TqzHSYSL4dls3U/5oZdjgyMy7ZIg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766729297; c=relaxed/simple; bh=eIsnakRWK5p4Ahq9BqvM6df2uHa/3SW/LOMnlOTiA9Y=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=WSsk//edY0hsuEHcnQb78MtH3Kpen622IB4ZY5rPBLqXmKqLlWeWVkrGWtzPQwUmE6yhz7+FjpWQ4bxcIwNnEWyt+LEjgXl5GV4l72h9oNX0U1S3KrRgIJxPVOiLKaU3mDX04J9JB8OWLF//YtEU7IUHshIRTZmxNg4CXgI4JxA= 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=ga3qv279; arc=none smtp.client-ip=115.124.30.119 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="ga3qv279" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1766729287; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=2dDam6/A7wKLN/SEOzZ9mYQr/Agu3pyZVWIzX0An9W4=; b=ga3qv279MPxTuv2FUef16+LJmAzAWM4Zu1z+nuMtiAoc95T3EzCh2bsGAobPPc+y8kFkjtu/78kGSHCYABOPo7mQxFaXW208nrJNPBJwL+IXntR3NpA9rQmVDhuyhdFuTNmIrYiE6JjTGD9qhaRTvPvaPTT+IkHSrOEzU7oukAU= Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0WvgaV-U_1766729284 cluster:ay36) by smtp.aliyun-inc.com; Fri, 26 Dec 2025 14:08:05 +0800 From: Baolin Wang To: akpm@linux-foundation.org, david@kernel.org, catalin.marinas@arm.com, will@kernel.org Cc: lorenzo.stoakes@oracle.com, ryan.roberts@arm.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, riel@surriel.com, harry.yoo@oracle.com, jannh@google.com, willy@infradead.org, baohua@kernel.org, dev.jain@arm.com, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 0/5] support batch checking of references and unmapping for large folios Date: Fri, 26 Dec 2025 14:07:54 +0800 Message-ID: X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Currently, folio_referenced_one() always checks the young flag for each PTE sequentially, which is inefficient for large folios. This inefficiency is especially noticeable when reclaiming clean file-backed large folios, where folio_referenced() is observed as a significant performance hotspot. Moreover, on Arm architecture, which supports contiguous PTEs, there is already an optimization to clear the young flags for PTEs within a contiguous range. However, this is not sufficient. We can extend this to perform batched operations for the entire large folio (which might exceed the contiguous range: CONT_PTE_SIZE). Similar to folio_referenced_one(), we can also apply batched unmapping for large file folios to optimize the performance of file folio reclamation. By supporting batched checking of the young flags, flushing TLB entries, and unmapping, I can observed a significant performance improvements in my performance tests for file folios reclamation. Please check the performance data in the commit message of each patch. Run stress-ng and mm selftests, no issues were found. Patch 1: Add a new generic batched PTE helper that supports batched checks of the references for large folios. Patch 2 - 3: Preparation patches. patch 4: Implement the Arm64 arch-specific clear_flush_young_ptes(). Patch 5: Support batched unmapping for file large folios. Changes from v4: - Fix passing the incorrect 'CONT_PTES' for non-batched APIs. - Rename ptep_clear_flush_young_notify() to clear_flush_young_ptes_notify() (per Ryan). - Fix some coding style issues (per Ryan). - Add reviewed tag from Ryan. Thanks. Changes from v3: - Fix using an incorrect parameter in ptep_clear_flush_young_notify() (per Liam). Changes from v2: - Rearrange the patch set (per Ryan). - Add pte_cont() check in clear_flush_young_ptes() (per Ryan). - Add a helper to do contpte block alignment (per Ryan). - Fix some coding style issues (per Lorenzo and Ryan). - Add more comments and update the commit message (per Lorenzo and Ryan). - Add acked tag from Barry. Thanks. Changes from v1: - Add a new patch to support batched unmapping for file large folios. - Update the cover letter Baolin Wang (5): mm: rmap: support batched checks of the references for large folios arm64: mm: factor out the address and ptep alignment into a new helper arm64: mm: support batch clearing of the young flag for large folios arm64: mm: implement the architecture-specific clear_flush_young_ptes() mm: rmap: support batched unmapping for file large folios arch/arm64/include/asm/pgtable.h | 23 ++++++++---- arch/arm64/mm/contpte.c | 62 ++++++++++++++++++++------------ include/linux/mmu_notifier.h | 9 ++--- include/linux/pgtable.h | 31 ++++++++++++++++ mm/rmap.c | 38 ++++++++++++++++---- 5 files changed, 125 insertions(+), 38 deletions(-) -- 2.47.3