Re: Two patches to speed up pg_rewind.

On Wed, Jan 27, 2021 at 09:18:48AM +0000, Paul Guo wrote:
> Second one is use copy_file_range() for the local rewind case to replace read()+write().
> This introduces copy_file_range() check and HAVE_COPY_FILE_RANGE so other
> code could use copy_file_range() if needed. copy_file_range() was introduced
> In high-version Linux Kernel, in low-version Linux or other Unix-like OS mmap()
> might be better than read()+write() but copy_file_range() is more interesting
> given that it could skip the data copying in some file systems - this could benefit more
> on Linux fs on network-based block storage.

Have you done some measurements?
--
Michael