Improve documentation about sharing a cache on NFS (#604)

diff --git a/doc/MANUAL.adoc b/doc/MANUAL.adoc
index be7b0c49ef32dec1b0de0c13be6711bb487aa867..446a59530ea76f33b4977da1241680b76c24449d 100644 (file)
--- a/doc/MANUAL.adoc
+++ b/doc/MANUAL.adoc
@@ -1232,6 +1232,11 @@ filesystems), but keep in mind that:
 * Having the cache on NFS may slow down compilation. Make sure to do some
   benchmarking to see if it's worth it.
 * ccache hasn't been tested very thoroughly on NFS.
+* If operating system versions is different then cache direct hit will be lesser,
+  and it will lead to slower cache preprocessor hits. sloppiness config can be set to 
+  system_headers to ignore different system header and increase cache direct hits.
+  It is recommended to have same operating system version when using cache on NFS
+  to increase cache direct hits.
 
 A tip is to set <<config_temporary_dir,*temporary_dir*>> to a directory on the
 local host to avoid NFS traffic for temporary files.