On 12/08/2018 05:37 AM, Eric Dumazet wrote: > Avoid cache line miss dereferencing struct page if we can. > > page_copy_sane() mostly deals with order-0 pages. > > Signed-off-by: Eric Dumazet <eduma...@google.com> > Cc: Al Viro <v...@zeniv.linux.org.uk> > --- > lib/iov_iter.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/lib/iov_iter.c b/lib/iov_iter.c > index > 54c248526b55fc498c996f2a5ea651262fcc7f61..2a1e282c3d38e2d03b075f54b7f9313e48b90289 > 100644 > --- a/lib/iov_iter.c > +++ b/lib/iov_iter.c > @@ -854,8 +854,18 @@ EXPORT_SYMBOL(_copy_from_iter_full_nocache); > > static inline bool page_copy_sane(struct page *page, size_t offset, size_t n) > { > - struct page *head = compound_head(page); > - size_t v = n + offset + page_address(page) - page_address(head); > + struct page *head; > + size_t v = n + offset; > + > + /* > + * Fast path if this is an order-0 page, > + * or if the copied area fits the first page of a compound one. > + */ > + if (likely(n <= v && v <= PAGE_SIZE)) > + return true; > + > + head = compound_head(page); > + v += (page - head) << PAGE_SHIFT; > > if (likely(n <= v && v <= (PAGE_SIZE << compound_order(head)))) > return true; > Hi Alexander ! Any news on this patch ? Thanks !