From cd0373b9b71ba61204326f54d500b878befb3408 Mon Sep 17 00:00:00 2001
From: Alessandro Rubini <rubini@gnudd.com>
Date: Tue, 31 Jan 2012 19:07:44 +0100
Subject: [PATCH] core: allocate control structures using an own kmem_cache
Testing /dev/urandom versus zzero-0-1-data (the random device)
shows this increases performance by 0.1 usecs per block. We
are now just over 0.7 usecs per block on my development PC.
This also introduces zio-core.c with generic stuff. We agree that zio-sys
will become zio-sysfs over time.
Signed-off-by: Alessandro Rubini <rubini@gnudd.com>
Acked-by: Federico Vaga <federico.vaga@gmail.com>
Conflicts:
Makefile
---
Makefile | 2 +-
include/linux/zio-buffer.h | 28 +++++---------------
zio-core.c | 52 ++++++++++++++++++++++++++++++++++++++
zio-sys.c | 5 ++++
4 files changed, 65 insertions(+), 22 deletions(-)
create mode 100644 zio-core.c
diff --git a/Makefile b/Makefile
index 234df62..4fd87a5 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
LINUX ?= /lib/modules/$(shell uname -r)/build
-zio-objs := zio-cdev.o zio-sys.o
+zio-objs := zio-core.o zio-cdev.o zio-sys.o
zio-objs += buffers/zio-buf-kmalloc.o triggers/zio-trig-user.o
obj-m = zio.o
diff --git a/include/linux/zio-buffer.h b/include/linux/zio-buffer.h
index 69d495e..28acf06 100644
--- a/include/linux/zio-buffer.h
+++ b/include/linux/zio-buffer.h
@@ -16,27 +16,6 @@
#define ZIO_DEFAULT_BUFFER "kmalloc" /* For devices with no own buffer type */
-/* FIXME: use a kmem_cache and real functions for control alloc/free */
-static inline struct zio_control *zio_alloc_control(gfp_t gfp)
-{
- struct zio_control *ctrl;
-
- ctrl = kzalloc(sizeof(*ctrl), gfp);
- if (!ctrl)
- return NULL;
- ctrl->major_version = ZIO_MAJOR_VERSION;
- ctrl->minor_version = ZIO_MINOR_VERSION;
- if (ntohl(1) == 1)
- ctrl->flags |= ZIO_CONTROL_BIG_ENDIAN;
- else
- ctrl->flags |= ZIO_CONTROL_LITTLE_ENDIAN;
- return ctrl;
-}
-static inline void zio_free_control(struct zio_control *ctrl)
-{
- kfree(ctrl);
-}
-
/*
* The following structure defines a buffer type, with methods.
* An instance is created for each channel using it
@@ -75,6 +54,13 @@ int __must_check zio_register_buf(struct zio_buffer_type *zbuf,
const char *name);
void zio_unregister_buf(struct zio_buffer_type *zbuf);
+/* We have our own kmem_cache (a.k.a. slab) for control structures */
+int zio_slab_init(void);
+void zio_slab_exit(void);
+struct zio_control *zio_alloc_control(gfp_t gfp);
+void zio_free_control(struct zio_control *ctrl);
+
+
struct zio_bi {
struct zio_obj_head head;
struct list_head list; /* instance list */
diff --git a/zio-core.c b/zio-core.c
new file mode 100644
index 0000000..1e382d3
--- /dev/null
+++ b/zio-core.c
@@ -0,0 +1,52 @@
+/* Alessandro Rubini, Federico Vaga for CERN, 2011, GNU GPLv2 or later */
+
+/*
+ * This file includes functions that build up the zio core, but are not
+ * strictly related to sysfs and configuration. Those are in zio-sysfs.c
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/zio.h>
+#include <linux/zio-buffer.h>
+
+/*
+ * We use a local slab for control structures.
+ */
+static struct kmem_cache *zio_ctrl_slab;
+
+struct zio_control *zio_alloc_control(gfp_t gfp)
+{
+ struct zio_control *ctrl;
+
+ ctrl = kmem_cache_alloc(zio_ctrl_slab, gfp);
+ if (!ctrl)
+ return NULL;
+ ctrl->major_version = ZIO_MAJOR_VERSION;
+ ctrl->minor_version = ZIO_MINOR_VERSION;
+ if (ntohl(1) == 1)
+ ctrl->flags |= ZIO_CONTROL_BIG_ENDIAN;
+ else
+ ctrl->flags |= ZIO_CONTROL_LITTLE_ENDIAN;
+ return ctrl;
+}
+
+void zio_free_control(struct zio_control *ctrl)
+{
+ kmem_cache_free(zio_ctrl_slab, ctrl);
+}
+
+int __init zio_slab_init(void)
+{
+ zio_ctrl_slab = KMEM_CACHE(zio_control, 0);
+ if (!zio_ctrl_slab)
+ return -ENOMEM;
+ return 0;
+}
+
+void zio_slab_exit(void) /* not __exit: called from zio_init on failures */
+{
+ if (zio_ctrl_slab)
+ kmem_cache_destroy(zio_ctrl_slab);
+ return;
+}
diff --git a/zio-sys.c b/zio-sys.c
index 2572e38..df08163 100644
--- a/zio-sys.c
+++ b/zio-sys.c
@@ -1745,6 +1745,9 @@ static int __init zio_init(void)
BUILD_BUG_ON(ZATTR_STD_NUM_ZBUF != ARRAY_SIZE(zio_zbuf_attr_names));
BUILD_BUG_ON(ZATTR_STD_NUM_TRIG != ARRAY_SIZE(zio_trig_attr_names));
+ err = zio_slab_init();
+ if (err)
+ return err;
/* Initialize char device */
err = __zio_register_cdev();
if (err)
@@ -1774,6 +1777,7 @@ static int __init zio_init(void)
out_kobj:
__zio_unregister_cdev();
out_cdev:
+ zio_slab_exit();
return err;
}
@@ -1792,6 +1796,7 @@ static void __exit zio_exit(void)
/* Remove char device */
__zio_unregister_cdev();
+ zio_slab_exit();
pr_info("zio-core had been unloaded\n");
return;
--
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