From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com [115.124.30.132]) (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 928C327FD45 for ; Fri, 19 Dec 2025 06:03:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.132 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766124193; cv=none; b=RVANdKogMljQjaOiJi5AJGqylD5PlZM6QAb9oeNHQ2TTI1NJNltZ5BAJ4GIc8WH0Z9gfAjHDoxOciDQodNlLZXzSq4YOy5mbVhiqOKUK5JRXJ/1Sj0EBuNh9mYBmOSs3a5rY/74lkHJLhP938bh2VWvZhBl7AyfaFwh4ycrO3vk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766124193; c=relaxed/simple; bh=Wnl9dBctRbW6fBiwQrqQEb+J1wHMmlY6GUIUIoIEWAw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=jkm6SGlpMsRKsjk7axFAeq9mP/mUoJ6hlFx6/uNMqZtwauwn94gATN4ffhgDunYQ3yimx1qwVTl/j4ClnyVlvrAuWCOgpO48fECEZFk3xUgpkyJBZAry7LcTPjggsfoIo0OfU0aZRwthiRnOjiQEJVJavRSWmkV0sUysyvSsmE0= 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=OhyQfoW0; arc=none smtp.client-ip=115.124.30.132 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="OhyQfoW0" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1766124183; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=BIdqt2wvzbrEXlhFP7v4o3aru+l73IP2t49PU+LeA10=; b=OhyQfoW08zdlkfieu+gFBJjBUNvrGMrEy9ZXSUB+GE0dUdtA2nejopRSIEXy7Od/s8qufv7zo1yG5JeWXKb9gQbeHLQIYC2FsYN0MK6WhBEx4/SAeGG1Q07w1tCUylXNiUedGYV7aSswLcCmXYftqY4usPGSanmhOM38e3hjjCo= Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0WvBZ2Df_1766124181 cluster:ay36) by smtp.aliyun-inc.com; Fri, 19 Dec 2025 14:03:02 +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 v3 0/5] support batch checking of references and unmapping for large folios Date: Fri, 19 Dec 2025 14:02:50 +0800 Message-ID: X-Mailer: git-send-email 2.43.7 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 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 | 35 ++++++++++++++++++ mm/rmap.c | 36 ++++++++++++++++--- 5 files changed, 128 insertions(+), 37 deletions(-) -- 2.47.3