(In reply to Ondrej Bilka from comment #29)
> Wait, do you have overlapping source and destination areas? If so then a
> backward copy is necessary.
Backward copy is often used for non-overlapping areas as it is faster on some Intel processors; see https://bugzilla.redhat.com/show_bug.cgi?id=638477#c99 for an explanation. I was pointing out that it also has the (unintended) behavior of pessimizing mmap()ed file accesses.
(In reply to Ondrej Bilka from comment #29)
> Wait, do you have overlapping source and destination areas? If so then a
> backward copy is necessary.
Backward copy is often used for non-overlapping areas as it is faster on some Intel processors; see https:/ /bugzilla. redhat. com/show_ bug.cgi? id=638477# c99 for an explanation. I was pointing out that it also has the (unintended) behavior of pessimizing mmap()ed file accesses.