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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 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 8FB171A0002 X-Stat-Signature: yyr671twz7kpsb9qwg5y6mwt9nz9mh5u X-Rspam-User: X-HE-Tag: 1746751535-358581 X-HE-Meta: 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 HC2hajkO EBalKBoKizxEZMRf9LXgVlXipdHqinGDAapmAGxPigLKbkRiGHQg+BnCWRx0BvWp7t2Vzgf1t0Q3nlyRKG+J2Po/cPhtWbNBE+Bw7HvyPgW9/rV+LhoylshY1m6ZUyKWr4A504hKvSlf1txnteyK9WpTzyARAqBi/F6vIR2R6HhnfsLunK9dzTah6Ve2KKX4o7/0k3mscQ25u0HWu6lgnGr+J3vL63ock4oRhD2dJx2ChoZ+byNY1srs9mfbeNduvZaIoL7XLBDKulHKKKt0OfZcQ3w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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