From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-110.freemail.mail.aliyun.com (out30-110.freemail.mail.aliyun.com [115.124.30.110]) (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 30BCB4A00 for ; Fri, 9 May 2025 00:45:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.110 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746751543; cv=none; b=gmRdz4h+nRdU6LVQds6K3LNoSI3zgk7qHhV/YDA0hn7pTCTFkE6FyWt/doP0bpms/FBqa69Z1mww8vf7TnNWSvqULubZ0yoNoy1qRrJZq00RyWQkECkwQpCcbDyxasTx9odEzcLE430BQH8QDy2h4eQLH6hMUT/azcDMvqCC1Ew= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746751543; c=relaxed/simple; bh=qewSU7Sq7g61DxSgIYVfGi2mLbJgj8aKyKmSToVQvU8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=dF0WnyuHpZT/HKLa5tWpT0fedtxd3FA4NlmUeFjFvWR1LWbldWHfeRjTl3gaelIu0Qb1nqC6AgYF/zzRzP0I18HfZsA6Ym2/4g5YPDvZlKhCTeSttQyGNJbvW5HOZobu6S7PGb8k0aVa9VYoDr8sDkl87JpM+9HqScKzDJVZ1fc= 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=vvOkThBX; arc=none smtp.client-ip=115.124.30.110 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="vvOkThBX" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1746751531; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=qjnjp9Z+cW5n7RR26tliecf8wD7X0OE0V0g/huCs4kU=; b=vvOkThBX8gR0s/1NcK0zObgKTZRWeufPlxN3lpeDSk+7I3aLIS8RcLlOt4VRxVZwNWQqr/NbxhqnE9iH51uhfZt0JawaCWtEY758YFHvu/5DKH8d1JOpIgVYYt3tByhBHpppKxe8UfLvC1ERtiTOXs+0jQRiEFeie/DPP6WiDSQ= Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0Wa0xfSH_1746751530 cluster:ay36) by smtp.aliyun-inc.com; Fri, 09 May 2025 08:45:31 +0800 From: Baolin Wang To: akpm@linux-foundation.org, david@redhat.com Cc: 21cnbao@gmail.com, ryan.roberts@arm.com, dev.jain@arm.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v3] mm: mincore: use pte_batch_bint() to batch process large folios Date: Fri, 9 May 2025 08:45:21 +0800 Message-ID: <99cb00ee626ceb6e788102ca36821815cd832237.1746697240.git.baolin.wang@linux.alibaba.com> X-Mailer: git-send-email 2.43.5 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When I tested the mincore() syscall, I observed that it takes longer with 64K mTHP enabled on my Arm64 server. The reason is the mincore_pte_range() still checks each PTE individually, even when the PTEs are contiguous, which is not efficient. Thus we can use pte_batch_hint() to get the batch number of the present contiguous PTEs, which can improve the performance. I tested the mincore() syscall with 1G anonymous memory populated with 64K mTHP, and observed an obvious performance improvement: w/o patch w/ patch changes 6022us 549us +91% Moreover, I also tested mincore() with disabling mTHP/THP, and did not see any obvious regression for base pages. Signed-off-by: Baolin Wang --- Changes from v2: - Re-calculate the max_nr, per Barry. Changes from v1: - Change to use pte_batch_hint() to get the batch number, per Ryan. Note: I observed the min_t() can introduce a slight performance regression for base pages, so I change to add a batch size check for base pages, which can resolve the performance regression issue. --- mm/mincore.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/mm/mincore.c b/mm/mincore.c index 832f29f46767..42d6c9c8da86 100644 --- a/mm/mincore.c +++ b/mm/mincore.c @@ -21,6 +21,7 @@ #include #include "swap.h" +#include "internal.h" static int mincore_hugetlb(pte_t *pte, unsigned long hmask, unsigned long addr, unsigned long end, struct mm_walk *walk) @@ -105,6 +106,7 @@ static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, pte_t *ptep; unsigned char *vec = walk->private; int nr = (end - addr) >> PAGE_SHIFT; + int step, i; ptl = pmd_trans_huge_lock(pmd, vma); if (ptl) { @@ -118,16 +120,26 @@ static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, walk->action = ACTION_AGAIN; return 0; } - for (; addr != end; ptep++, addr += PAGE_SIZE) { + for (; addr != end; ptep += step, addr += step * PAGE_SIZE) { pte_t pte = ptep_get(ptep); + step = 1; /* We need to do cache lookup too for pte markers */ if (pte_none_mostly(pte)) __mincore_unmapped_range(addr, addr + PAGE_SIZE, vma, vec); - else if (pte_present(pte)) - *vec = 1; - else { /* pte is a swap entry */ + else if (pte_present(pte)) { + unsigned int batch = pte_batch_hint(ptep, pte); + + if (batch > 1) { + unsigned int max_nr = (end - addr) >> PAGE_SHIFT; + + step = min_t(unsigned int, batch, max_nr); + } + + for (i = 0; i < step; i++) + vec[i] = 1; + } else { /* pte is a swap entry */ swp_entry_t entry = pte_to_swp_entry(pte); if (non_swap_entry(entry)) { @@ -146,7 +158,7 @@ static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, #endif } } - vec++; + vec += step; } pte_unmap_unlock(ptep - 1, ptl); out: -- 2.43.5