Update io engine comments
Some were plain wrong, mainly because they were born through
copying an existing engine.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/engines/cpu.c b/engines/cpu.c
index b6f9075..d10669d 100644
--- a/engines/cpu.c
+++ b/engines/cpu.c
@@ -1,3 +1,10 @@
+/*
+ * CPU engine
+ *
+ * Doesn't transfer any data, merely burns CPU cycles according to
+ * the settings.
+ *
+ */
#include "../fio.h"
#include "../os.h"
diff --git a/engines/libaio.c b/engines/libaio.c
index 5295ead..78f43ef 100644
--- a/engines/libaio.c
+++ b/engines/libaio.c
@@ -1,5 +1,7 @@
/*
- * native linux aio io engine
+ * libaio engine
+ *
+ * IO engine using the Linux native aio interface.
*
*/
#include <stdio.h>
diff --git a/engines/mmap.c b/engines/mmap.c
index 0922e97..17cf5fc 100644
--- a/engines/mmap.c
+++ b/engines/mmap.c
@@ -1,5 +1,8 @@
/*
- * regular read/write sync io engine
+ * mmap engine
+ *
+ * IO engine that reads/writes from files by doing memcpy to/from
+ * a memory mapped region of the file.
*
*/
#include <stdio.h>
diff --git a/engines/net.c b/engines/net.c
index cd1fda9..51bc671 100644
--- a/engines/net.c
+++ b/engines/net.c
@@ -1,5 +1,8 @@
/*
- * Transfer data over the net.
+ * net engine
+ *
+ * IO engine that reads/writes to/from sockets.
+ *
*/
#include <stdio.h>
#include <stdlib.h>
diff --git a/engines/null.c b/engines/null.c
index 42a780a..6397ec0 100644
--- a/engines/null.c
+++ b/engines/null.c
@@ -1,5 +1,8 @@
/*
- * null engine - doesn't do any transfers. Used to test fio.
+ * null engine
+ *
+ * IO engine that doesn't do any real IO transfers, it just pretends to.
+ * The main purpose is to test fio itself.
*
*/
#include <stdio.h>
diff --git a/engines/posixaio.c b/engines/posixaio.c
index 9ee3ca6..7d9aaaf 100644
--- a/engines/posixaio.c
+++ b/engines/posixaio.c
@@ -1,5 +1,7 @@
/*
- * posix aio io engine
+ * posixaio engine
+ *
+ * IO engine that uses the posix defined aio interface.
*
*/
#include <stdio.h>
diff --git a/engines/sg.c b/engines/sg.c
index 98ecbd1..84c2afe 100644
--- a/engines/sg.c
+++ b/engines/sg.c
@@ -1,5 +1,7 @@
/*
- * scsi generic sg v3 io engine
+ * sg engine
+ *
+ * IO engine that uses the Linux SG v3 interface to talk to SCSI devices
*
*/
#include <stdio.h>
diff --git a/engines/splice.c b/engines/splice.c
index c366a2e..59bf7e4 100644
--- a/engines/splice.c
+++ b/engines/splice.c
@@ -1,5 +1,8 @@
/*
- * splice io engine
+ * splice engine
+ *
+ * IO engine that transfers data by doing splices to/from pipes and
+ * the files.
*
*/
#include <stdio.h>
diff --git a/engines/sync.c b/engines/sync.c
index b1776d2..a137282 100644
--- a/engines/sync.c
+++ b/engines/sync.c
@@ -1,5 +1,8 @@
/*
- * regular read/write sync io engine
+ * sync engine
+ *
+ * IO engine that does regular read(2)/write(2) with lseek(2) to transfer
+ * data.
*
*/
#include <stdio.h>
diff --git a/engines/syslet-rw.c b/engines/syslet-rw.c
index fe400da..279884a 100644
--- a/engines/syslet-rw.c
+++ b/engines/syslet-rw.c
@@ -1,5 +1,8 @@
/*
- * read/write() engine that uses syslet to be async
+ * syslet engine
+ *
+ * IO engine that does regular pread(2)/pwrite(2) to transfer data, but
+ * with syslets to make the execution async.
*
*/
#include <stdio.h>