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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: DC2DC140004 X-Stat-Signature: tcpdtppcmtucdi3sne56z6a6fdtktsp6 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1746775852-47215 X-HE-Meta: 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 IklH/7Fa 0ua5p61mZEl/grfckzDNFUke981j1+YqdQlsHoCMg7xnoWOiAA4X5HIzUchtp7m6pBT1aGJcVD5jglfmYEu3JsVYsf/scrxcabse8GdWAB2B2ICSGML8wB/YYzjWaRsfvhmf9y752M3hV3gIezQJqoCrDH7cjmVyk/Y8Cjvd64rSwog/jebQH1dVp7VSKoD212JAYlOuLJSbtw9h+zmJVaJ4f8uSYF7eYsBofkZovlIbGVt4V+6KFig1yEjGovaV7DVYaXyhcLuQhnoo= 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: On 09/05/25 6:15 am, Baolin Wang wrote: > 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 Nit: The subject line - s/pte_batch_bint()/pte_batch_hint() Otherwise LGTM Reviewed-by: Dev Jain > --- > 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: