This patch optimises csum_partial_copy_generic() by making use of cache
instructions (dcbt/dcbz) just like copy_tofrom_user() does
On a TCP benchmark using socklib on the loopback interface on which checksum
offload and scatter/gather have been deactivated, we get about 20% performance
increase.
Christophe Leroy (2):
powerpc32: checksum_wrappers_64 becomes checksum_wrappers
powerpc32: rewrite of csum_partial_copy_generic based of copy_tofrom_user
arch/powerpc/include/asm/checksum.h | 9 -
arch/powerpc/lib/Makefile | 3 +-
arch/powerpc/lib/checksum_32.S | 320 +++++++++++++++++++++-----------
arch/powerpc/lib/checksum_wrappers.c | 102 ++++++++++
arch/powerpc/lib/checksum_wrappers_64.c | 102 ----------
5 files changed, 312 insertions(+), 224 deletions(-)
create mode 100644 arch/powerpc/lib/checksum_wrappers.c
delete mode 100644 arch/powerpc/lib/checksum_wrappers_64.c
--
2.1.0
The powerpc64 checksum wrapper functions adds the csum_and_copy_to_user() which
otherwise is implemented in include/net/checksum.h by using csum_partial() then
copy_to_user()
Those two wrapper fonctions are also applicable to powerpc32 as it is based on
the use of csum_partial_copy_generic() which also exists on powerpc32
This patch renames arch/powerpc/lib/checksum_wrappers_64.c to
arch/powerpc/lib/checksum_wrappers.c and
makes it non-conditional to CONFIG_WORD_SIZE
Signed-off-by: Christophe Leroy <[email protected]>
---
arch/powerpc/include/asm/checksum.h | 9 ---
arch/powerpc/lib/Makefile | 3 +-
arch/powerpc/lib/checksum_wrappers.c | 102 ++++++++++++++++++++++++++++++++
arch/powerpc/lib/checksum_wrappers_64.c | 102 --------------------------------
4 files changed, 103 insertions(+), 113 deletions(-)
create mode 100644 arch/powerpc/lib/checksum_wrappers.c
delete mode 100644 arch/powerpc/lib/checksum_wrappers_64.c
diff --git a/arch/powerpc/include/asm/checksum.h b/arch/powerpc/include/asm/checksum.h
index 8251a3b..0ffd793 100644
--- a/arch/powerpc/include/asm/checksum.h
+++ b/arch/powerpc/include/asm/checksum.h
@@ -56,21 +56,12 @@ extern __wsum csum_partial_copy_generic(const void *src, void *dst,
int len, __wsum sum,
int *src_err, int *dst_err);
-#ifdef __powerpc64__
#define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
extern __wsum csum_and_copy_from_user(const void __user *src, void *dst,
int len, __wsum sum, int *err_ptr);
#define HAVE_CSUM_COPY_USER
extern __wsum csum_and_copy_to_user(const void *src, void __user *dst,
int len, __wsum sum, int *err_ptr);
-#else
-/*
- * the same as csum_partial, but copies from src to dst while it
- * checksums.
- */
-#define csum_partial_copy_from_user(src, dst, len, sum, errp) \
- csum_partial_copy_generic((__force const void *)(src), (dst), (len), (sum), (errp), NULL)
-#endif
#define csum_partial_copy_nocheck(src, dst, len, sum) \
csum_partial_copy_generic((src), (dst), (len), (sum), NULL, NULL)
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index a47e142..e46b068 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -22,8 +22,7 @@ obj64-$(CONFIG_SMP) += locks.o
obj64-$(CONFIG_ALTIVEC) += vmx-helper.o
ifeq ($(CONFIG_GENERIC_CSUM),)
-obj-y += checksum_$(CONFIG_WORD_SIZE).o
-obj-$(CONFIG_PPC64) += checksum_wrappers_64.o
+obj-y += checksum_$(CONFIG_WORD_SIZE).o checksum_wrappers.o
endif
obj-$(CONFIG_PPC_EMULATE_SSTEP) += sstep.o ldstfp.o
diff --git a/arch/powerpc/lib/checksum_wrappers.c b/arch/powerpc/lib/checksum_wrappers.c
new file mode 100644
index 0000000..08e3a33
--- /dev/null
+++ b/arch/powerpc/lib/checksum_wrappers.c
@@ -0,0 +1,102 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2010
+ *
+ * Author: Anton Blanchard <[email protected]>
+ */
+#include <linux/export.h>
+#include <linux/compiler.h>
+#include <linux/types.h>
+#include <asm/checksum.h>
+#include <asm/uaccess.h>
+
+__wsum csum_and_copy_from_user(const void __user *src, void *dst,
+ int len, __wsum sum, int *err_ptr)
+{
+ unsigned int csum;
+
+ might_sleep();
+
+ *err_ptr = 0;
+
+ if (!len) {
+ csum = 0;
+ goto out;
+ }
+
+ if (unlikely((len < 0) || !access_ok(VERIFY_READ, src, len))) {
+ *err_ptr = -EFAULT;
+ csum = (__force unsigned int)sum;
+ goto out;
+ }
+
+ csum = csum_partial_copy_generic((void __force *)src, dst,
+ len, sum, err_ptr, NULL);
+
+ if (unlikely(*err_ptr)) {
+ int missing = __copy_from_user(dst, src, len);
+
+ if (missing) {
+ memset(dst + len - missing, 0, missing);
+ *err_ptr = -EFAULT;
+ } else {
+ *err_ptr = 0;
+ }
+
+ csum = csum_partial(dst, len, sum);
+ }
+
+out:
+ return (__force __wsum)csum;
+}
+EXPORT_SYMBOL(csum_and_copy_from_user);
+
+__wsum csum_and_copy_to_user(const void *src, void __user *dst, int len,
+ __wsum sum, int *err_ptr)
+{
+ unsigned int csum;
+
+ might_sleep();
+
+ *err_ptr = 0;
+
+ if (!len) {
+ csum = 0;
+ goto out;
+ }
+
+ if (unlikely((len < 0) || !access_ok(VERIFY_WRITE, dst, len))) {
+ *err_ptr = -EFAULT;
+ csum = -1; /* invalid checksum */
+ goto out;
+ }
+
+ csum = csum_partial_copy_generic(src, (void __force *)dst,
+ len, sum, NULL, err_ptr);
+
+ if (unlikely(*err_ptr)) {
+ csum = csum_partial(src, len, sum);
+
+ if (copy_to_user(dst, src, len)) {
+ *err_ptr = -EFAULT;
+ csum = -1; /* invalid checksum */
+ }
+ }
+
+out:
+ return (__force __wsum)csum;
+}
+EXPORT_SYMBOL(csum_and_copy_to_user);
diff --git a/arch/powerpc/lib/checksum_wrappers_64.c b/arch/powerpc/lib/checksum_wrappers_64.c
deleted file mode 100644
index 08e3a33..0000000
--- a/arch/powerpc/lib/checksum_wrappers_64.c
+++ /dev/null
@@ -1,102 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
- *
- * Copyright (C) IBM Corporation, 2010
- *
- * Author: Anton Blanchard <[email protected]>
- */
-#include <linux/export.h>
-#include <linux/compiler.h>
-#include <linux/types.h>
-#include <asm/checksum.h>
-#include <asm/uaccess.h>
-
-__wsum csum_and_copy_from_user(const void __user *src, void *dst,
- int len, __wsum sum, int *err_ptr)
-{
- unsigned int csum;
-
- might_sleep();
-
- *err_ptr = 0;
-
- if (!len) {
- csum = 0;
- goto out;
- }
-
- if (unlikely((len < 0) || !access_ok(VERIFY_READ, src, len))) {
- *err_ptr = -EFAULT;
- csum = (__force unsigned int)sum;
- goto out;
- }
-
- csum = csum_partial_copy_generic((void __force *)src, dst,
- len, sum, err_ptr, NULL);
-
- if (unlikely(*err_ptr)) {
- int missing = __copy_from_user(dst, src, len);
-
- if (missing) {
- memset(dst + len - missing, 0, missing);
- *err_ptr = -EFAULT;
- } else {
- *err_ptr = 0;
- }
-
- csum = csum_partial(dst, len, sum);
- }
-
-out:
- return (__force __wsum)csum;
-}
-EXPORT_SYMBOL(csum_and_copy_from_user);
-
-__wsum csum_and_copy_to_user(const void *src, void __user *dst, int len,
- __wsum sum, int *err_ptr)
-{
- unsigned int csum;
-
- might_sleep();
-
- *err_ptr = 0;
-
- if (!len) {
- csum = 0;
- goto out;
- }
-
- if (unlikely((len < 0) || !access_ok(VERIFY_WRITE, dst, len))) {
- *err_ptr = -EFAULT;
- csum = -1; /* invalid checksum */
- goto out;
- }
-
- csum = csum_partial_copy_generic(src, (void __force *)dst,
- len, sum, NULL, err_ptr);
-
- if (unlikely(*err_ptr)) {
- csum = csum_partial(src, len, sum);
-
- if (copy_to_user(dst, src, len)) {
- *err_ptr = -EFAULT;
- csum = -1; /* invalid checksum */
- }
- }
-
-out:
- return (__force __wsum)csum;
-}
-EXPORT_SYMBOL(csum_and_copy_to_user);
--
2.1.0
csum_partial_copy_generic() does the same as copy_tofrom_user and also
calculates the checksum during the copy. Unlike copy_tofrom_user(), the existing
version of csum_partial_copy_generic() doesn't take benefit of the cache
This patch is a rewrite of csum_partial_copy_generic() based on
copy_tofrom_user().
The previous version of csum_partial_copy_generic() was handling errors. Now we
have the checksum wrapper functions to handle the error case like in powerpc64
so we can make the error case simple: just return -EFAULT.
copy_tofrom_user() only has r12 available => we use it for the checksum
r7 and r8 which contains pointers to error feedback are used, so we stack them.
On a TCP benchmark using socklib on the loopback interface on which checksum
offload and scatter/gather have been deactivated, we get about 20% performance
increase.
Signed-off-by: Christophe Leroy <[email protected]>
---
arch/powerpc/lib/checksum_32.S | 320 +++++++++++++++++++++++++++--------------
1 file changed, 209 insertions(+), 111 deletions(-)
diff --git a/arch/powerpc/lib/checksum_32.S b/arch/powerpc/lib/checksum_32.S
index 7874e8a..7b95a68 100644
--- a/arch/powerpc/lib/checksum_32.S
+++ b/arch/powerpc/lib/checksum_32.S
@@ -14,6 +14,7 @@
#include <linux/sys.h>
#include <asm/processor.h>
+#include <asm/cache.h>
#include <asm/errno.h>
#include <asm/ppc_asm.h>
@@ -103,123 +104,220 @@ _GLOBAL(csum_partial)
*
* csum_partial_copy_generic(src, dst, len, sum, src_err, dst_err)
*/
+#define CSUM_COPY_16_BYTES_WITHEX(n) \
+8 ## n ## 0: \
+ lwz r7,4(r4); \
+8 ## n ## 1: \
+ lwz r8,8(r4); \
+8 ## n ## 2: \
+ lwz r9,12(r4); \
+8 ## n ## 3: \
+ lwzu r10,16(r4); \
+8 ## n ## 4: \
+ stw r7,4(r6); \
+ adde r12,r12,r7; \
+8 ## n ## 5: \
+ stw r8,8(r6); \
+ adde r12,r12,r8; \
+8 ## n ## 6: \
+ stw r9,12(r6); \
+ adde r12,r12,r9; \
+8 ## n ## 7: \
+ stwu r10,16(r6); \
+ adde r12,r12,r10
+
+#define CSUM_COPY_16_BYTES_EXCODE(n) \
+.section __ex_table,"a"; \
+ .align 2; \
+ .long 8 ## n ## 0b,src_error; \
+ .long 8 ## n ## 1b,src_error; \
+ .long 8 ## n ## 2b,src_error; \
+ .long 8 ## n ## 3b,src_error; \
+ .long 8 ## n ## 4b,dst_error; \
+ .long 8 ## n ## 5b,dst_error; \
+ .long 8 ## n ## 6b,dst_error; \
+ .long 8 ## n ## 7b,dst_error; \
+ .text
+
+ .text
+ .stabs "arch/powerpc/lib/",N_SO,0,0,0f
+ .stabs "checksum_32.S",N_SO,0,0,0f
+0:
+
+CACHELINE_BYTES = L1_CACHE_BYTES
+LG_CACHELINE_BYTES = L1_CACHE_SHIFT
+CACHELINE_MASK = (L1_CACHE_BYTES-1)
+
_GLOBAL(csum_partial_copy_generic)
- addic r0,r6,0
- subi r3,r3,4
- subi r4,r4,4
- srwi. r6,r5,2
- beq 3f /* if we're doing < 4 bytes */
- andi. r9,r4,2 /* Align dst to longword boundary */
- beq+ 1f
-81: lhz r6,4(r3) /* do 2 bytes to get aligned */
- addi r3,r3,2
- subi r5,r5,2
-91: sth r6,4(r4)
- addi r4,r4,2
- addc r0,r0,r6
- srwi. r6,r5,2 /* # words to do */
- beq 3f
-1: srwi. r6,r5,4 /* # groups of 4 words to do */
- beq 10f
- mtctr r6
-71: lwz r6,4(r3)
-72: lwz r9,8(r3)
-73: lwz r10,12(r3)
-74: lwzu r11,16(r3)
- adde r0,r0,r6
-75: stw r6,4(r4)
- adde r0,r0,r9
-76: stw r9,8(r4)
- adde r0,r0,r10
-77: stw r10,12(r4)
- adde r0,r0,r11
-78: stwu r11,16(r4)
- bdnz 71b
-10: rlwinm. r6,r5,30,30,31 /* # words left to do */
- beq 13f
- mtctr r6
-82: lwzu r9,4(r3)
-92: stwu r9,4(r4)
- adde r0,r0,r9
- bdnz 82b
-13: andi. r5,r5,3
-3: cmpwi 0,r5,2
- blt+ 4f
-83: lhz r6,4(r3)
- addi r3,r3,2
- subi r5,r5,2
-93: sth r6,4(r4)
+ stwu r1,-16(r1)
+ stw r7,12(r1)
+ stw r8,8(r1)
+
+ andi. r0,r4,1 /* is destination address even ? */
+ cmplwi cr7,r0,0
+ addic r12,r6,0
+ addi r6,r4,-4
+ neg r0,r4
+ addi r4,r3,-4
+ andi. r0,r0,CACHELINE_MASK /* # bytes to start of cache line */
+ beq 58f
+
+ cmplw 0,r5,r0 /* is this more than total to do? */
+ blt 63f /* if not much to do */
+ andi. r8,r0,3 /* get it word-aligned first */
+ mtctr r8
+ beq+ 61f
+ li r3,0
+70: lbz r9,4(r4) /* do some bytes */
+ addi r4,r4,1
+ slwi r3,r3,8
+ rlwimi r3,r9,0,24,31
+71: stb r9,4(r6)
+ addi r6,r6,1
+ bdnz 70b
+ adde r12,r12,r3
+61: subf r5,r0,r5
+ srwi. r0,r0,2
+ mtctr r0
+ beq 58f
+72: lwzu r9,4(r4) /* do some words */
+ adde r12,r12,r9
+73: stwu r9,4(r6)
+ bdnz 72b
+
+58: srwi. r0,r5,LG_CACHELINE_BYTES /* # complete cachelines */
+ clrlwi r5,r5,32-LG_CACHELINE_BYTES
+ li r11,4
+ beq 63f
+
+ /* Here we decide how far ahead to prefetch the source */
+ li r3,4
+ cmpwi r0,1
+ li r7,0
+ ble 114f
+ li r7,1
+#if MAX_COPY_PREFETCH > 1
+ /* Heuristically, for large transfers we prefetch
+ MAX_COPY_PREFETCH cachelines ahead. For small transfers
+ we prefetch 1 cacheline ahead. */
+ cmpwi r0,MAX_COPY_PREFETCH
+ ble 112f
+ li r7,MAX_COPY_PREFETCH
+112: mtctr r7
+111: dcbt r3,r4
+ addi r3,r3,CACHELINE_BYTES
+ bdnz 111b
+#else
+ dcbt r3,r4
+ addi r3,r3,CACHELINE_BYTES
+#endif /* MAX_COPY_PREFETCH > 1 */
+
+114: subf r8,r7,r0
+ mr r0,r7
+ mtctr r8
+
+53: dcbt r3,r4
+54: dcbz r11,r6
+/* the main body of the cacheline loop */
+ CSUM_COPY_16_BYTES_WITHEX(0)
+#if L1_CACHE_BYTES >= 32
+ CSUM_COPY_16_BYTES_WITHEX(1)
+#if L1_CACHE_BYTES >= 64
+ CSUM_COPY_16_BYTES_WITHEX(2)
+ CSUM_COPY_16_BYTES_WITHEX(3)
+#if L1_CACHE_BYTES >= 128
+ CSUM_COPY_16_BYTES_WITHEX(4)
+ CSUM_COPY_16_BYTES_WITHEX(5)
+ CSUM_COPY_16_BYTES_WITHEX(6)
+ CSUM_COPY_16_BYTES_WITHEX(7)
+#endif
+#endif
+#endif
+ bdnz 53b
+ cmpwi r0,0
+ li r3,4
+ li r7,0
+ bne 114b
+
+63: srwi. r0,r5,2
+ mtctr r0
+ beq 64f
+30: lwzu r0,4(r4)
+ adde r12,r12,r0
+31: stwu r0,4(r6)
+ bdnz 30b
+
+64: andi. r0,r5,2
+ beq+ 65f
+40: lhz r0,4(r4)
addi r4,r4,2
- adde r0,r0,r6
-4: cmpwi 0,r5,1
- bne+ 5f
-84: lbz r6,4(r3)
-94: stb r6,4(r4)
- slwi r6,r6,8 /* Upper byte of word */
- adde r0,r0,r6
-5: addze r3,r0 /* add in final carry */
+41: sth r0,4(r6)
+ adde r12,r12,r0
+ addi r6,r6,2
+65: andi. r0,r5,1
+ beq+ 66f
+50: lbz r0,4(r4)
+51: stb r0,4(r6)
+ slwi r0,r0,8
+ adde r12,r12,r0
+66: addze r3,r12
+ addi r1,r1,16
+ beqlr+ cr7
+ rlwinm r3,r3,8,0,31 /* swap bytes for odd destination */
blr
-/* These shouldn't go in the fixup section, since that would
- cause the ex_table addresses to get out of order. */
-
-src_error_4:
- mfctr r6 /* update # bytes remaining from ctr */
- rlwimi r5,r6,4,0,27
- b 79f
-src_error_1:
- li r6,0
- subi r5,r5,2
-95: sth r6,4(r4)
- addi r4,r4,2
-79: srwi. r6,r5,2
- beq 3f
- mtctr r6
-src_error_2:
- li r6,0
-96: stwu r6,4(r4)
- bdnz 96b
-3: andi. r5,r5,3
- beq src_error
-src_error_3:
- li r6,0
- mtctr r5
- addi r4,r4,3
-97: stbu r6,1(r4)
- bdnz 97b
+/* read fault */
src_error:
- cmpwi 0,r7,0
- beq 1f
- li r6,-EFAULT
- stw r6,0(r7)
-1: addze r3,r0
+ lwz r7,12(r1)
+ addi r1,r1,16
+ cmpwi cr0,r7,0
+ beqlr
+ li r0,-EFAULT
+ stw r0,0(r7)
blr
-
+/* write fault */
dst_error:
- cmpwi 0,r8,0
- beq 1f
- li r6,-EFAULT
- stw r6,0(r8)
-1: addze r3,r0
+ lwz r8,8(r1)
+ addi r1,r1,16
+ cmpwi cr0,r8,0
+ beqlr
+ li r0,-EFAULT
+ stw r0,0(r8)
blr
-.section __ex_table,"a"
- .long 81b,src_error_1
- .long 91b,dst_error
- .long 71b,src_error_4
- .long 72b,src_error_4
- .long 73b,src_error_4
- .long 74b,src_error_4
- .long 75b,dst_error
- .long 76b,dst_error
- .long 77b,dst_error
- .long 78b,dst_error
- .long 82b,src_error_2
- .long 92b,dst_error
- .long 83b,src_error_3
- .long 93b,dst_error
- .long 84b,src_error_3
- .long 94b,dst_error
- .long 95b,dst_error
- .long 96b,dst_error
- .long 97b,dst_error
+ .section __ex_table,"a"
+ .align 2
+ .long 70b,src_error
+ .long 71b,dst_error
+ .long 72b,src_error
+ .long 73b,dst_error
+ .long 54b,dst_error
+ .text
+
+/*
+ * this stuff handles faults in the cacheline loop and branches to either
+ * src_error (if in read part) or dst_error (if in write part)
+ */
+ CSUM_COPY_16_BYTES_EXCODE(0)
+#if L1_CACHE_BYTES >= 32
+ CSUM_COPY_16_BYTES_EXCODE(1)
+#if L1_CACHE_BYTES >= 64
+ CSUM_COPY_16_BYTES_EXCODE(2)
+ CSUM_COPY_16_BYTES_EXCODE(3)
+#if L1_CACHE_BYTES >= 128
+ CSUM_COPY_16_BYTES_EXCODE(4)
+ CSUM_COPY_16_BYTES_EXCODE(5)
+ CSUM_COPY_16_BYTES_EXCODE(6)
+ CSUM_COPY_16_BYTES_EXCODE(7)
+#endif
+#endif
+#endif
+
+ .section __ex_table,"a"
+ .align 2
+ .long 30b,src_error
+ .long 31b,dst_error
+ .long 40b,src_error
+ .long 41b,dst_error
+ .long 50b,src_error
+ .long 51b,dst_error
--
2.1.0
On Mon, 2015-06-22 at 19:01 +0200, Christophe Leroy wrote:
> The powerpc64 checksum wrapper functions adds the
> csum_and_copy_to_user() which
> otherwise is implemented in include/net/checksum.h by using
> csum_partial() then
> copy_to_user()
>
> Those two wrapper fonctions are also applicable to powerpc32 as it
> is based on
> the use of csum_partial_copy_generic() which also exists on powerpc32
>
> This patch renames arch/powerpc/lib/checksum_wrappers_64.c to
> arch/powerpc/lib/checksum_wrappers.c and
> makes it non-conditional to CONFIG_WORD_SIZE
>
> Signed-off-by: Christophe Leroy <[email protected]>
> ---
> arch/powerpc/include/asm/checksum.h | 9 ---
> arch/powerpc/lib/Makefile | 3 +-
> arch/powerpc/lib/checksum_wrappers.c | 102
> ++++++++++++++++++++++++++++++++
> arch/powerpc/lib/checksum_wrappers_64.c | 102 ----------------------
> ----------
Please pass "-M -C" to git format-patch so we can see if anything
changed while being moved.
-Scott