Use a faster 7z command line by default

In tests with one typical XML dump, -mx=4 looked much better than -mx=5
in terms of CPU cost, with negligible losses in compression.
Merged downstream by Wikia: https://github.com/Wikia/app/pull/6118

It probably makes sense to explicitly adopt a default suitable for XML
dumps; but later this should be configurable in scripts etc. (T78669).

Change-Id: I07ab5f93ecd6d706460691db5181de89ef31cbea

diff --git a/includes/Export.php b/includes/Export.php
index 4600feb..0d55d7d 100644 (file)
--- a/includes/Export.php
+++ b/includes/Export.php
@@ -1191,7 +1191,7 @@ class Dump7ZipOutput extends DumpPipeOutput {
         * @return string
         */
        function setup7zCommand( $file ) {
-               $command = "7za a -bd -si " . wfEscapeShellArg( $file );
+               $command = "7za a -bd -si -mx=4 " . wfEscapeShellArg( $file );
                // Suppress annoying useless crap from p7zip
                // Unfortunately this could suppress real error messages too
                $command .= ' >' . wfGetNull() . ' 2>&1';