From dc2676210c425ee8e5cb1bec5bc84d004ddf4179 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Fri, 13 Feb 2015 08:25:59 -0500 Subject: [PATCH] dm crypt: offload writes to thread Submitting write bios directly in the encryption thread caused serious performance degradation. On a multiprocessor machine, encryption requests finish in a different order than they were submitted. Consequently, write requests would be submitted in a different order and it could cause severe performance degradation. Move the submission of write requests to a separate thread so that the requests can be sorted before submitting. But this commit improves dm-crypt performance even without having dm-crypt perform request sorting (in particular it enables IO schedulers like CFQ to sort more effectively). Note: it is required that a previous commit ("dm crypt: don't allocate pages for a partial request") be applied before applying this patch. Otherwise, this commit could introduce a crash. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer --- Reading git-format-patch failed