ima: introduce multi-page collect buffers

Use of multiple-page collect buffers reduces:
1) the number of block IO requests
2) the number of asynchronous hash update requests

Second is important for HW accelerated hashing, because significant
amount of time is spent for preparation of hash update operation,
which includes configuring acceleration HW, DMA engine, etc...
Thus, HW accelerators are more efficient when working on large
chunks of data.

This patch introduces usage of multi-page collect buffers. Buffer size
can be specified using 'ahash_bufsize' module parameter. Default buffer
size is 4096 bytes.

Changes in v3:
- kernel parameter replaced with module parameter

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 775fe039e060..8b2ab548b6e4 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1322,6 +1322,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			different crypto accelerators. This option can be used
 			to achieve the best performance for a particular HW.
 
+	ima.ahash_bufsize= [IMA] Asynchronous hash buffer size
+			Format: <bufsize>
+			Set hashing buffer size. Default: 4k.
+
+			ahash performance varies for different chunk sizes on
+			different crypto accelerators. This option can be used
+			to achieve best performance for particular HW.
+
 	init=		[KNL]
 			Format: <full_path>
 			Run specified binary instead of /sbin/init as init