Hi Matteo, Have you tried Glibc generic implementation code? ref: https://lore.kernel.org/linux-arch/20190629053641.3iBfk9-I_D29cDp9yJnIdIg7oMtHNZlDmhLQPTumhEc@z/#t If Glibc codes have the same performance in your hardware, then you could give a generic implementation first. The current Linux generic implementation is so simple in lib/string.c: #ifndef __HAVE_ARCH_MEMCPY /** * memcpy - Copy one area of memory to another * @dest: Where to copy to * @src: Where to copy from * @count: The size of the area. * * You should not use this function to access IO space, use memcpy_toio() * or memcpy_fromio() instead. */ void *memcpy(void *dest, const void *src, size_t count) { char *tmp = dest; const char *s = src; while (count--) *tmp++ = *s++; return dest; } EXPORT_SYMBOL(memcpy); #endif On Tue, Jun 15, 2021 at 10:42 AM Matteo Croce <mcroce@xxxxxxxxxxxxxxxxxxx> wrote: > > From: Matteo Croce <mcroce@xxxxxxxxxxxxx> > > Write a C version of memcpy() which uses the biggest data size allowed, > without generating unaligned accesses. > > The procedure is made of three steps: > First copy data one byte at time until the destination buffer is aligned > to a long boundary. > Then copy the data one long at time shifting the current and the next u8 > to compose a long at every cycle. > Finally, copy the remainder one byte at time. > > On a BeagleV, the TCP RX throughput increased by 45%: > > before: > > $ iperf3 -c beaglev > Connecting to host beaglev, port 5201 > [ 5] local 192.168.85.6 port 44840 connected to 192.168.85.48 port 5201 > [ ID] Interval Transfer Bitrate Retr Cwnd > [ 5] 0.00-1.00 sec 76.4 MBytes 641 Mbits/sec 27 624 KBytes > [ 5] 1.00-2.00 sec 72.5 MBytes 608 Mbits/sec 0 708 KBytes > [ 5] 2.00-3.00 sec 73.8 MBytes 619 Mbits/sec 10 451 KBytes > [ 5] 3.00-4.00 sec 72.5 MBytes 608 Mbits/sec 0 564 KBytes > [ 5] 4.00-5.00 sec 73.8 MBytes 619 Mbits/sec 0 658 KBytes > [ 5] 5.00-6.00 sec 73.8 MBytes 619 Mbits/sec 14 522 KBytes > [ 5] 6.00-7.00 sec 73.8 MBytes 619 Mbits/sec 0 621 KBytes > [ 5] 7.00-8.00 sec 72.5 MBytes 608 Mbits/sec 0 706 KBytes > [ 5] 8.00-9.00 sec 73.8 MBytes 619 Mbits/sec 20 580 KBytes > [ 5] 9.00-10.00 sec 73.8 MBytes 619 Mbits/sec 0 672 KBytes > - - - - - - - - - - - - - - - - - - - - - - - - - > [ ID] Interval Transfer Bitrate Retr > [ 5] 0.00-10.00 sec 736 MBytes 618 Mbits/sec 71 sender > [ 5] 0.00-10.01 sec 733 MBytes 615 Mbits/sec receiver > > after: > > $ iperf3 -c beaglev > Connecting to host beaglev, port 5201 > [ 5] local 192.168.85.6 port 44864 connected to 192.168.85.48 port 5201 > [ ID] Interval Transfer Bitrate Retr Cwnd > [ 5] 0.00-1.00 sec 109 MBytes 912 Mbits/sec 48 559 KBytes > [ 5] 1.00-2.00 sec 108 MBytes 902 Mbits/sec 0 690 KBytes > [ 5] 2.00-3.00 sec 106 MBytes 891 Mbits/sec 36 396 KBytes > [ 5] 3.00-4.00 sec 108 MBytes 902 Mbits/sec 0 567 KBytes > [ 5] 4.00-5.00 sec 106 MBytes 891 Mbits/sec 0 699 KBytes > [ 5] 5.00-6.00 sec 106 MBytes 891 Mbits/sec 32 414 KBytes > [ 5] 6.00-7.00 sec 106 MBytes 891 Mbits/sec 0 583 KBytes > [ 5] 7.00-8.00 sec 106 MBytes 891 Mbits/sec 0 708 KBytes > [ 5] 8.00-9.00 sec 106 MBytes 891 Mbits/sec 28 433 KBytes > [ 5] 9.00-10.00 sec 108 MBytes 902 Mbits/sec 0 591 KBytes > - - - - - - - - - - - - - - - - - - - - - - - - - > [ ID] Interval Transfer Bitrate Retr > [ 5] 0.00-10.00 sec 1.04 GBytes 897 Mbits/sec 144 sender > [ 5] 0.00-10.01 sec 1.04 GBytes 894 Mbits/sec receiver > > And the decreased CPU time of the memcpy() is observable with perf top. > This is the `perf top -Ue task-clock` output when doing the test: > > before: > > Overhead Shared O Symbol > 42.22% [kernel] [k] memcpy > 35.00% [kernel] [k] __asm_copy_to_user > 3.50% [kernel] [k] sifive_l2_flush64_range > 2.30% [kernel] [k] stmmac_napi_poll_rx > 1.11% [kernel] [k] memset > > after: > > Overhead Shared O Symbol > 45.69% [kernel] [k] __asm_copy_to_user > 29.06% [kernel] [k] memcpy > 4.09% [kernel] [k] sifive_l2_flush64_range > 2.77% [kernel] [k] stmmac_napi_poll_rx > 1.24% [kernel] [k] memset > > Signed-off-by: Matteo Croce <mcroce@xxxxxxxxxxxxx> > --- > arch/riscv/include/asm/string.h | 8 ++- > arch/riscv/kernel/riscv_ksyms.c | 2 - > arch/riscv/lib/Makefile | 2 +- > arch/riscv/lib/memcpy.S | 108 -------------------------------- > arch/riscv/lib/string.c | 94 +++++++++++++++++++++++++++ > 5 files changed, 101 insertions(+), 113 deletions(-) > delete mode 100644 arch/riscv/lib/memcpy.S > create mode 100644 arch/riscv/lib/string.c > > diff --git a/arch/riscv/include/asm/string.h b/arch/riscv/include/asm/string.h > index 909049366555..6b5d6fc3eab4 100644 > --- a/arch/riscv/include/asm/string.h > +++ b/arch/riscv/include/asm/string.h > @@ -12,9 +12,13 @@ > #define __HAVE_ARCH_MEMSET > extern asmlinkage void *memset(void *, int, size_t); > extern asmlinkage void *__memset(void *, int, size_t); > + > +#ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE > #define __HAVE_ARCH_MEMCPY > -extern asmlinkage void *memcpy(void *, const void *, size_t); > -extern asmlinkage void *__memcpy(void *, const void *, size_t); > +extern void *memcpy(void *dest, const void *src, size_t count); > +extern void *__memcpy(void *dest, const void *src, size_t count); > +#endif > + > #define __HAVE_ARCH_MEMMOVE > extern asmlinkage void *memmove(void *, const void *, size_t); > extern asmlinkage void *__memmove(void *, const void *, size_t); > diff --git a/arch/riscv/kernel/riscv_ksyms.c b/arch/riscv/kernel/riscv_ksyms.c > index 5ab1c7e1a6ed..3f6d512a5b97 100644 > --- a/arch/riscv/kernel/riscv_ksyms.c > +++ b/arch/riscv/kernel/riscv_ksyms.c > @@ -10,8 +10,6 @@ > * Assembly functions that may be used (directly or indirectly) by modules > */ > EXPORT_SYMBOL(memset); > -EXPORT_SYMBOL(memcpy); > EXPORT_SYMBOL(memmove); > EXPORT_SYMBOL(__memset); > -EXPORT_SYMBOL(__memcpy); > EXPORT_SYMBOL(__memmove); > diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile > index 25d5c9664e57..2ffe85d4baee 100644 > --- a/arch/riscv/lib/Makefile > +++ b/arch/riscv/lib/Makefile > @@ -1,9 +1,9 @@ > # SPDX-License-Identifier: GPL-2.0-only > lib-y += delay.o > -lib-y += memcpy.o > lib-y += memset.o > lib-y += memmove.o > lib-$(CONFIG_MMU) += uaccess.o > lib-$(CONFIG_64BIT) += tishift.o > +lib-$(CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE) += string.o > > obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o > diff --git a/arch/riscv/lib/memcpy.S b/arch/riscv/lib/memcpy.S > deleted file mode 100644 > index 51ab716253fa..000000000000 > --- a/arch/riscv/lib/memcpy.S > +++ /dev/null > @@ -1,108 +0,0 @@ > -/* SPDX-License-Identifier: GPL-2.0-only */ > -/* > - * Copyright (C) 2013 Regents of the University of California > - */ > - > -#include <linux/linkage.h> > -#include <asm/asm.h> > - > -/* void *memcpy(void *, const void *, size_t) */ > -ENTRY(__memcpy) > -WEAK(memcpy) > - move t6, a0 /* Preserve return value */ > - > - /* Defer to byte-oriented copy for small sizes */ > - sltiu a3, a2, 128 > - bnez a3, 4f > - /* Use word-oriented copy only if low-order bits match */ > - andi a3, t6, SZREG-1 > - andi a4, a1, SZREG-1 > - bne a3, a4, 4f > - > - beqz a3, 2f /* Skip if already aligned */ > - /* > - * Round to nearest double word-aligned address > - * greater than or equal to start address > - */ > - andi a3, a1, ~(SZREG-1) > - addi a3, a3, SZREG > - /* Handle initial misalignment */ > - sub a4, a3, a1 > -1: > - lb a5, 0(a1) > - addi a1, a1, 1 > - sb a5, 0(t6) > - addi t6, t6, 1 > - bltu a1, a3, 1b > - sub a2, a2, a4 /* Update count */ > - > -2: > - andi a4, a2, ~((16*SZREG)-1) > - beqz a4, 4f > - add a3, a1, a4 > -3: > - REG_L a4, 0(a1) > - REG_L a5, SZREG(a1) > - REG_L a6, 2*SZREG(a1) > - REG_L a7, 3*SZREG(a1) > - REG_L t0, 4*SZREG(a1) > - REG_L t1, 5*SZREG(a1) > - REG_L t2, 6*SZREG(a1) > - REG_L t3, 7*SZREG(a1) > - REG_L t4, 8*SZREG(a1) > - REG_L t5, 9*SZREG(a1) > - REG_S a4, 0(t6) > - REG_S a5, SZREG(t6) > - REG_S a6, 2*SZREG(t6) > - REG_S a7, 3*SZREG(t6) > - REG_S t0, 4*SZREG(t6) > - REG_S t1, 5*SZREG(t6) > - REG_S t2, 6*SZREG(t6) > - REG_S t3, 7*SZREG(t6) > - REG_S t4, 8*SZREG(t6) > - REG_S t5, 9*SZREG(t6) > - REG_L a4, 10*SZREG(a1) > - REG_L a5, 11*SZREG(a1) > - REG_L a6, 12*SZREG(a1) > - REG_L a7, 13*SZREG(a1) > - REG_L t0, 14*SZREG(a1) > - REG_L t1, 15*SZREG(a1) > - addi a1, a1, 16*SZREG > - REG_S a4, 10*SZREG(t6) > - REG_S a5, 11*SZREG(t6) > - REG_S a6, 12*SZREG(t6) > - REG_S a7, 13*SZREG(t6) > - REG_S t0, 14*SZREG(t6) > - REG_S t1, 15*SZREG(t6) > - addi t6, t6, 16*SZREG > - bltu a1, a3, 3b > - andi a2, a2, (16*SZREG)-1 /* Update count */ > - > -4: > - /* Handle trailing misalignment */ > - beqz a2, 6f > - add a3, a1, a2 > - > - /* Use word-oriented copy if co-aligned to word boundary */ > - or a5, a1, t6 > - or a5, a5, a3 > - andi a5, a5, 3 > - bnez a5, 5f > -7: > - lw a4, 0(a1) > - addi a1, a1, 4 > - sw a4, 0(t6) > - addi t6, t6, 4 > - bltu a1, a3, 7b > - > - ret > - > -5: > - lb a4, 0(a1) > - addi a1, a1, 1 > - sb a4, 0(t6) > - addi t6, t6, 1 > - bltu a1, a3, 5b > -6: > - ret > -END(__memcpy) > diff --git a/arch/riscv/lib/string.c b/arch/riscv/lib/string.c > new file mode 100644 > index 000000000000..525f9ee25a74 > --- /dev/null > +++ b/arch/riscv/lib/string.c > @@ -0,0 +1,94 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * String functions optimized for hardware which doesn't > + * handle unaligned memory accesses efficiently. > + * > + * Copyright (C) 2021 Matteo Croce > + */ > + > +#include <linux/types.h> > +#include <linux/module.h> > + > +/* size below a classic byte at time copy is done */ > +#define MIN_THRESHOLD 64 > + > +/* convenience types to avoid cast between different pointer types */ > +union types { > + u8 *u8; > + unsigned long *ulong; > + uintptr_t uptr; > +}; > + > +union const_types { > + const u8 *u8; > + unsigned long *ulong; > +}; > + > +void *memcpy(void *dest, const void *src, size_t count) > +{ > + const int bytes_long = BITS_PER_LONG / 8; > +#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS > + const int mask = bytes_long - 1; > + const int distance = (src - dest) & mask; > +#endif > + union const_types s = { .u8 = src }; > + union types d = { .u8 = dest }; > + > +#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS > + if (count <= MIN_THRESHOLD) > + goto copy_remainder; > + > + /* copy a byte at time until destination is aligned */ > + for (; count && d.uptr & mask; count--) > + *d.u8++ = *s.u8++; > + > + if (distance) { > + unsigned long last, next; > + > + /* move s backward to the previous alignment boundary */ > + s.u8 -= distance; > + > + /* 32/64 bit wide copy from s to d. > + * d is aligned now but s is not, so read s alignment wise, > + * and do proper shift to get the right value. > + * Works only on Little Endian machines. > + */ > + for (next = s.ulong[0]; count >= bytes_long + mask; count -= bytes_long) { > + last = next; > + next = s.ulong[1]; > + > + d.ulong[0] = last >> (distance * 8) | > + next << ((bytes_long - distance) * 8); > + > + d.ulong++; > + s.ulong++; > + } > + > + /* restore s with the original offset */ > + s.u8 += distance; > + } else > +#endif > + { > + /* if the source and dest lower bits are the same, do a simple > + * 32/64 bit wide copy. > + */ > + for (; count >= bytes_long; count -= bytes_long) > + *d.ulong++ = *s.ulong++; > + } > + > + /* suppress warning when CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y */ > + goto copy_remainder; > + > +copy_remainder: > + while (count--) > + *d.u8++ = *s.u8++; > + > + return dest; > +} > +EXPORT_SYMBOL(memcpy); > + > +void *__memcpy(void *dest, const void *src, size_t count) > +{ > + return memcpy(dest, src, count); > +} > +EXPORT_SYMBOL(__memcpy); > -- > 2.31.1 > -- Best Regards Guo Ren ML: https://lore.kernel.org/linux-csky/
