| Message ID | 20230130201833.27042-2-vishal.moola@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Convert various mempolicy.c functions to use folios | expand |
On 1/31/2023 4:18 AM, Vishal Moola (Oracle) wrote: > folio_estimated_sharers() takes in a folio and returns the precise > number of times the first subpage of the folio is mapped. > > This function aims to provide an estimate for the number of sharers of a > folio. This is necessary for folio conversions where we care > about the number of processes that share a folio, but don't necessarily > want to check every single page within that folio. > > This is in contrast to folio_mapcount() which calculates the total > number of the times a folio and all its subpages are mapped. > > Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com> Reviewed-by: Yin Fengwei <fengwei.yin@intel.com> Regards Yin, Fengwei > --- > include/linux/mm.h | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 27b34f7730e7..c91bf9cdb3d0 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -1905,6 +1905,24 @@ static inline size_t folio_size(struct folio *folio) > return PAGE_SIZE << folio_order(folio); > } > > +/** > + * folio_estimated_sharers - Estimate the number of sharers of a folio. > + * @folio: The folio. > + * > + * folio_estimated_sharers() aims to serve as a function to efficiently > + * estimate the number of processes sharing a folio. This is done by > + * looking at the precise mapcount of the first subpage in the folio, and > + * assuming the other subpages are the same. This may not be true for large > + * folios. If you want exact mapcounts for exact calculations, look at > + * page_mapcount() or folio_total_mapcount(). > + * > + * Return: The estimated number of processes sharing a folio. > + */ > +static inline int folio_estimated_sharers(struct folio *folio) > +{ > + return page_mapcount(folio_page(folio, 0)); > +} > + > #ifndef HAVE_ARCH_MAKE_PAGE_ACCESSIBLE > static inline int arch_make_page_accessible(struct page *page) > {
On 30.01.23 21:18, Vishal Moola (Oracle) wrote: > folio_estimated_sharers() takes in a folio and returns the precise > number of times the first subpage of the folio is mapped. > > This function aims to provide an estimate for the number of sharers of a > folio. This is necessary for folio conversions where we care > about the number of processes that share a folio, but don't necessarily > want to check every single page within that folio. > > This is in contrast to folio_mapcount() which calculates the total > number of the times a folio and all its subpages are mapped. > > Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com> > --- > include/linux/mm.h | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 27b34f7730e7..c91bf9cdb3d0 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -1905,6 +1905,24 @@ static inline size_t folio_size(struct folio *folio) > return PAGE_SIZE << folio_order(folio); > } > > +/** > + * folio_estimated_sharers - Estimate the number of sharers of a folio. > + * @folio: The folio. > + * > + * folio_estimated_sharers() aims to serve as a function to efficiently > + * estimate the number of processes sharing a folio. This is done by > + * looking at the precise mapcount of the first subpage in the folio, and > + * assuming the other subpages are the same. This may not be true for large > + * folios. If you want exact mapcounts for exact calculations, look at > + * page_mapcount() or folio_total_mapcount(). > + * > + * Return: The estimated number of processes sharing a folio. > + */ > +static inline int folio_estimated_sharers(struct folio *folio) > +{ > + return page_mapcount(folio_page(folio, 0)); > +} > + > #ifndef HAVE_ARCH_MAKE_PAGE_ACCESSIBLE > static inline int arch_make_page_accessible(struct page *page) > { Acked-by: David Hildenbrand <david@redhat.com>
diff --git a/include/linux/mm.h b/include/linux/mm.h index 27b34f7730e7..c91bf9cdb3d0 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1905,6 +1905,24 @@ static inline size_t folio_size(struct folio *folio) return PAGE_SIZE << folio_order(folio); } +/** + * folio_estimated_sharers - Estimate the number of sharers of a folio. + * @folio: The folio. + * + * folio_estimated_sharers() aims to serve as a function to efficiently + * estimate the number of processes sharing a folio. This is done by + * looking at the precise mapcount of the first subpage in the folio, and + * assuming the other subpages are the same. This may not be true for large + * folios. If you want exact mapcounts for exact calculations, look at + * page_mapcount() or folio_total_mapcount(). + * + * Return: The estimated number of processes sharing a folio. + */ +static inline int folio_estimated_sharers(struct folio *folio) +{ + return page_mapcount(folio_page(folio, 0)); +} + #ifndef HAVE_ARCH_MAKE_PAGE_ACCESSIBLE static inline int arch_make_page_accessible(struct page *page) {
folio_estimated_sharers() takes in a folio and returns the precise number of times the first subpage of the folio is mapped. This function aims to provide an estimate for the number of sharers of a folio. This is necessary for folio conversions where we care about the number of processes that share a folio, but don't necessarily want to check every single page within that folio. This is in contrast to folio_mapcount() which calculates the total number of the times a folio and all its subpages are mapped. Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com> --- include/linux/mm.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)