For performance reasons, it's sometimes preferable to read a file instead of mmap'ing it. Read scales better on some multiprocessor systems, for example, and read appears to require fewer NFS ops than mmap if the file is on an NFS-mounted filesystem.
Here's my proposal for changing the httpd and apr-util to support run-time selection of mmap:
apr-util changes: - Add "apr_bucket_file_allow_mmap(int)" to allow apps to enable or disable mmap on a per-file basis. (Default is to allow mmap,for backward compatibility.)
httpd changes:
- Add a new config directive "EnableMMAP (on|off)", default=on.
- In the core handler, after creating a file bucket, call
apr_bucket_file_allow_mmap(false) if mmap has been disabled for this dir.
--Brian
