| Message ID | 88c8a8c68d87429f0fc48e81100f19b71f6e664f.1661240170.git.baolin.wang@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Fix some issues when looking up hugetlb page | expand |
On 23.08.22 09:50, Baolin Wang wrote: > Considering the pmd entries of a CONT-PMD hugetlb can not span on > multiple PMDs, we can change to use the PMD page lock, which can > be much finer grain that lock in the mm. > > Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> > --- > include/linux/hugetlb.h | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index 3a96f67..d4803a89 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -892,9 +892,17 @@ static inline gfp_t htlb_modify_alloc_mask(struct hstate *h, gfp_t gfp_mask) > static inline spinlock_t *huge_pte_lockptr(struct hstate *h, > struct mm_struct *mm, pte_t *pte) > { > - VM_BUG_ON(huge_page_size(h) == PAGE_SIZE); > + unsigned long hp_size = huge_page_size(h); > > - if (huge_page_size(h) == PMD_SIZE) { > + VM_BUG_ON(hp_size == PAGE_SIZE); > + > + /* > + * Considering CONT-PMD size hugetlb, since the CONT-PMD entry > + * can not span multiple PMDs, then we can use the fine grained > + * PMD page lock. > + */ > + if (hp_size == PMD_SIZE || > + (hp_size > PMD_SIZE && hp_size < PUD_SIZE)) { > return pmd_lockptr(mm, (pmd_t *) pte); > } else if (huge_page_size(h) < PMD_SIZE) { > unsigned long mask = ~(PTRS_PER_PTE * sizeof(pte_t) - 1); Is there a measurable performance gain? IOW, do we really care?
On 8/23/2022 4:14 PM, David Hildenbrand wrote: > On 23.08.22 09:50, Baolin Wang wrote: >> Considering the pmd entries of a CONT-PMD hugetlb can not span on >> multiple PMDs, we can change to use the PMD page lock, which can >> be much finer grain that lock in the mm. >> >> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> >> --- >> include/linux/hugetlb.h | 12 ++++++++++-- >> 1 file changed, 10 insertions(+), 2 deletions(-) >> >> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h >> index 3a96f67..d4803a89 100644 >> --- a/include/linux/hugetlb.h >> +++ b/include/linux/hugetlb.h >> @@ -892,9 +892,17 @@ static inline gfp_t htlb_modify_alloc_mask(struct hstate *h, gfp_t gfp_mask) >> static inline spinlock_t *huge_pte_lockptr(struct hstate *h, >> struct mm_struct *mm, pte_t *pte) >> { >> - VM_BUG_ON(huge_page_size(h) == PAGE_SIZE); >> + unsigned long hp_size = huge_page_size(h); >> >> - if (huge_page_size(h) == PMD_SIZE) { >> + VM_BUG_ON(hp_size == PAGE_SIZE); >> + >> + /* >> + * Considering CONT-PMD size hugetlb, since the CONT-PMD entry >> + * can not span multiple PMDs, then we can use the fine grained >> + * PMD page lock. >> + */ >> + if (hp_size == PMD_SIZE || >> + (hp_size > PMD_SIZE && hp_size < PUD_SIZE)) { >> return pmd_lockptr(mm, (pmd_t *) pte); >> } else if (huge_page_size(h) < PMD_SIZE) { >> unsigned long mask = ~(PTRS_PER_PTE * sizeof(pte_t) - 1); > > Is there a measurable performance gain? IOW, do we really care? IMO, It's just a theoretical analysis now:) Let me think about how to measure the performance gain.
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 3a96f67..d4803a89 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -892,9 +892,17 @@ static inline gfp_t htlb_modify_alloc_mask(struct hstate *h, gfp_t gfp_mask) static inline spinlock_t *huge_pte_lockptr(struct hstate *h, struct mm_struct *mm, pte_t *pte) { - VM_BUG_ON(huge_page_size(h) == PAGE_SIZE); + unsigned long hp_size = huge_page_size(h); - if (huge_page_size(h) == PMD_SIZE) { + VM_BUG_ON(hp_size == PAGE_SIZE); + + /* + * Considering CONT-PMD size hugetlb, since the CONT-PMD entry + * can not span multiple PMDs, then we can use the fine grained + * PMD page lock. + */ + if (hp_size == PMD_SIZE || + (hp_size > PMD_SIZE && hp_size < PUD_SIZE)) { return pmd_lockptr(mm, (pmd_t *) pte); } else if (huge_page_size(h) < PMD_SIZE) { unsigned long mask = ~(PTRS_PER_PTE * sizeof(pte_t) - 1);
Considering the pmd entries of a CONT-PMD hugetlb can not span on multiple PMDs, we can change to use the PMD page lock, which can be much finer grain that lock in the mm. Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> --- include/linux/hugetlb.h | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)