memcpy() generates different code depending on compiler option you
select for your cpu optimization. Defining odp version for such trivial
thing will definitely compiler optimizations things to 0. It might be
useful only for some accounting cases. If for example we want to do some
debug
function to count how many memcpy() we did. But accounting for memcpy()
looks very strange for me.
I would like to have calls for linux specific things in odp. To be more
OS independent and available for other OS porting.
Maxim.
On 10/16/2015 16:09, Bill Fischofer wrote:
Correction. I see rte_memcpy.h is broken down by ARCH directory and
in the x86 directory is various hoop jumping. However I also found an
interesting performance study at
http://nadeausoftware.com/articles/2012/05/c_c_tip_how_copy_memory_quickly
on this subject.
Money quote:
* |memcpy( )| is always the fastest method to copy data. A great
compiler, like ICC, can optimize loops to do as well.
This is a good example of letting the compiler do it's job. In almost
all cases memcpy() is treated as a compiler intrinsic, allowing the
compiler to do all of its tricks to achieve best performance.
On Fri, Oct 16, 2015 at 7:55 AM, Bill Fischofer
<[email protected] <mailto:[email protected]>> wrote:
DPDK contains the line:
#define rte_memcpy(d, s, n) memcpy((d), (s), (n))
All of the other definitions in rte_memcpy.h for the various
"optimized" moves do the same. So I'm not sure what's the point
here. It's not as if these functions aren't already heavily
optimized by C compilers.
On Fri, Oct 16, 2015 at 7:22 AM, Savolainen, Petri (Nokia -
FI/Espoo) <[email protected]
<mailto:[email protected]>> wrote:
If that’s the case an platform can implement these without
extra effort. But when that’s not the case, an implementation
can use whatever special instructions, vector engines or DMA
HW it has to speed up these calls. See e.g. rte_memcpy in DPDK
- it’s not just plain memcpy wrapper (they must have had a
reason for optimizing it).
-Petri
*From:*EXT Bill Fischofer [mailto:[email protected]
<mailto:[email protected]>]
*Sent:* Friday, October 16, 2015 3:17 PM
*To:* Savolainen, Petri (Nokia - FI/Espoo)
*Cc:* LNG ODP Mailman List
*Subject:* Re: [lng-odp] [API-NEXT PATCH] api: clib: added
standard c library api
Why would you not expect a platform to provide an optimized
implementation of these stdlib functions itself? GCC, in
particular, seems to do a good job of this for most platforms.
On Fri, Oct 16, 2015 at 7:13 AM, Petri Savolainen
<[email protected]
<mailto:[email protected]>> wrote:
Some C library calls are often used in data plane code. This
API enables possibility to HW optimized implementation of those.
Added first memcpy and memset.
Signed-off-by: Petri Savolainen <[email protected]
<mailto:[email protected]>>
---
include/odp.h | 1 +
include/odp/api/std_clib.h | 64
+++++++++++++++++++++++++++
platform/linux-generic/Makefile.am | 2 +
platform/linux-generic/include/odp/std_clib.h | 30 +++++++++++++
4 files changed, 97 insertions(+)
create mode 100644 include/odp/api/std_clib.h
create mode 100644 platform/linux-generic/include/odp/std_clib.h
diff --git a/include/odp.h b/include/odp.h
index 825c7e1..f2cd2d3 100644
--- a/include/odp.h
+++ b/include/odp.h
@@ -56,6 +56,7 @@ extern "C" {
#include <odp/thrmask.h>
#include <odp/spinlock_recursive.h>
#include <odp/rwlock_recursive.h>
+#include <odp/std_clib.h>
#ifdef __cplusplus
}
diff --git a/include/odp/api/std_clib.h
b/include/odp/api/std_clib.h
new file mode 100644
index 0000000..2119ec4
--- /dev/null
+++ b/include/odp/api/std_clib.h
@@ -0,0 +1,64 @@
+/* Copyright (c) 2015, Linaro Limited
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+/**
+ * @file
+ *
+ * ODP version of often used C library calls
+ */
+
+#ifndef ODP_API_STD_CLIB_H_
+#define ODP_API_STD_CLIB_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @defgroup odp_std_clib ODP STD CLIB
+ * @details
+ * ODP version of often used C library calls
+ * @{
+ */
+
+/**
+ * Memcpy
+ *
+ * ODP version of C library memcpy function. It copies 'num'
bytes from source
+ * to destination address. Source and destination memory
blocks must not
+ * overlap.
+ *
+ * @param dst Pointer to destination memory block
+ * @param src Pointer to source memory block
+ * @param num Number of bytes to copy
+ *
+ * @return 'dst' address
+ */
+void *odp_memcpy(void *dst, const void *src, size_t num);
+
+/**
+ * Memset
+ *
+ * ODP version of C library memset function. It sets 'value'
to first 'num'
+ * bytes of memory block pointed by 'ptr'.
+ *
+ * @param ptr Pointer to the memory block
+ * @param value Value to be set
+ * @param num Number of bytes to set
+ *
+ * @return 'ptr' address
+ */
+void *odp_memset(void *ptr, int value, size_t num);
+
+/**
+ * @}
+ */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/platform/linux-generic/Makefile.am
b/platform/linux-generic/Makefile.am
index 85c976d..fc202cc 100644
--- a/platform/linux-generic/Makefile.am
+++ b/platform/linux-generic/Makefile.am
@@ -41,6 +41,7 @@ odpinclude_HEADERS = \
$(srcdir)/include/odp/shared_memory.h \
$(srcdir)/include/odp/spinlock.h \
$(srcdir)/include/odp/spinlock_recursive.h \
+ $(srcdir)/include/odp/std_clib.h \
$(srcdir)/include/odp/std_types.h \
$(srcdir)/include/odp/sync.h \
$(srcdir)/include/odp/system_info.h \
@@ -108,6 +109,7 @@ odpapiinclude_HEADERS = \
$(top_srcdir)/include/odp/api/shared_memory.h \
$(top_srcdir)/include/odp/api/spinlock.h \
$(top_srcdir)/include/odp/api/spinlock_recursive.h \
+ $(top_srcdir)/include/odp/api/std_clib.h \
$(top_srcdir)/include/odp/api/std_types.h \
$(top_srcdir)/include/odp/api/sync.h \
$(top_srcdir)/include/odp/api/system_info.h \
diff --git a/platform/linux-generic/include/odp/std_clib.h
b/platform/linux-generic/include/odp/std_clib.h
new file mode 100644
index 0000000..c939c48
--- /dev/null
+++ b/platform/linux-generic/include/odp/std_clib.h
@@ -0,0 +1,30 @@
+/* Copyright (c) 2015, Linaro Limited
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef ODP_PLAT_STD_CLIB_H_
+#define ODP_PLAT_STD_CLIB_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <odp/api/std_types.h>
+
+static inline void *odp_memcpy(void *dst, const void *src,
size_t num)
+{
+ return memcpy(dst, src, num);
+}
+
+static inline void *odp_memset(void *ptr, int value, size_t num)
+{
+ return memset(ptr, value, num);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
--
2.6.0
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