From: Jens Axboe <axboe@fb.com>
Date: Fri, 14 Mar 2014 18:24:28 +0000 (-0600)
Subject: Don't scramble buffers if compression is enabled
X-Git-Tag: fio-2.1.7~10
X-Git-Url: https://git.kernel.dk/?p=fio.git;a=commitdiff_plain;h=0574c885b82aea0332ab5fa35af84db0f3946726

Don't scramble buffers if compression is enabled

For the other buffer settings (like patterns, or whether always
to refill or not), we don't do the slight header scramble if
they are enabled. Do they same for compression settings, otherwise
we can skew the compression results.

Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/init.c b/init.c
index 73ec9eb2..0a872c0f 100644
--- a/init.c
+++ b/init.c
@@ -856,6 +856,11 @@ int ioengine_load(struct thread_data *td)
 	return 0;
 }
 
+static int compression_enabled(struct thread_options *o)
+{
+	return o->compress_percentage || o->compress_chunk;
+}
+
 static void init_flags(struct thread_data *td)
 {
 	struct thread_options *o = &td->o;
@@ -868,8 +873,14 @@ static void init_flags(struct thread_data *td)
 		td->flags |= TD_F_READ_IOLOG;
 	if (o->refill_buffers)
 		td->flags |= TD_F_REFILL_BUFFERS;
-	if (o->scramble_buffers)
+
+	/*
+	 * Don't scramble buffers if we set any of the compression
+	 * settings
+	 */
+	if (o->scramble_buffers && !compression_enabled(o))
 		td->flags |= TD_F_SCRAMBLE_BUFFERS;
+
 	if (o->verify != VERIFY_NONE)
 		td->flags |= TD_F_VER_NONE;
 }