From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 98D0AC433F5 for ; Thu, 30 Sep 2021 01:25:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 71296615E5 for ; Thu, 30 Sep 2021 01:25:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346718AbhI3B0m (ORCPT ); Wed, 29 Sep 2021 21:26:42 -0400 Received: from mail.kernel.org ([198.145.29.99]:54858 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229477AbhI3B0l (ORCPT ); Wed, 29 Sep 2021 21:26:41 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3A745615E6; Thu, 30 Sep 2021 01:24:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1632965099; bh=9UwRNhH+QUgXvsQcSHsRIJoQjd68Bzhy/GzdrwVADlc=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=kxaMWiBvWWzwdWP6y5ScKiNQ+rgkQosRAEYFE+4JQyW2MeFx1CVAy6mH302q+A4WC 0ABkq5tC0detJXp1DDwitkPCf5eWjZ2r77QtMR9PtIlpD1QXALOHUAWmZZnYoAUq2J WDnr0zk4gTKtYAnucun3KXWYnuW2u7gR+EhmRfNyb/O6MK7/zd+gZusfuv4VgrfAxA 05QF8cqS4xYWJAWk+kbCUcBlHwGhSIs2FjZRv6PPzWmAObu6rqCvT7u0GUOn8yIEnF AwCIUhkdLGwaL2xWbeF+ltmDApMUGxvvb5WbeuKCYdLjeLsxMhu0aXHdGfMlyl6Wla PKssoHytbSqtg== Received: by mail-ua1-f44.google.com with SMTP id c33so2969780uae.9; Wed, 29 Sep 2021 18:24:59 -0700 (PDT) X-Gm-Message-State: AOAM532kPQq1tlZjn+FmXOJMP/2y3Qx5X2z6f/mrmPBJAlaayqzqanPR heoVCUM39TkH01ZTN4CI7AZgluFX/245kAahGPg= X-Google-Smtp-Source: ABdhPJxr4nyuS3T6e/1IiTSYUMT71ALIxV3VM+0ngW+OYcCbfpfRLq7KAUbH04GJbR74OsIrmP3zaH8LcVoJbV1j7Rs= X-Received: by 2002:ab0:6ec6:: with SMTP id c6mr3629624uav.97.1632965098324; Wed, 29 Sep 2021 18:24:58 -0700 (PDT) MIME-Version: 1.0 References: <20210929172234.31620-1-mcroce@linux.microsoft.com> <20210929172234.31620-2-mcroce@linux.microsoft.com> In-Reply-To: <20210929172234.31620-2-mcroce@linux.microsoft.com> From: Guo Ren Date: Thu, 30 Sep 2021 09:24:47 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v5 1/3] riscv: optimized memcpy To: Matteo Croce Cc: linux-riscv , Linux Kernel Mailing List , linux-arch , Paul Walmsley , Palmer Dabbelt , Albert Ou , Atish Patra , Emil Renner Berthing , Akira Tsukamoto , Drew Fustini , Bin Meng , David Laight , Christoph Hellwig Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 30, 2021 at 1:22 AM Matteo Croce wrote: > > From: Matteo Croce > > 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 > Reported-by: kernel test robot > --- > 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 | 90 ++++++++++++++++++++++++++ > 5 files changed, 97 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 What's the problem with the -O3 & -Os? If the user uses CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 that will cause bad performance for memcpy? Seems asm version is more compatible? > #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 > -#include > - > -/* 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..bfc912ee23f8 > --- /dev/null > +++ b/arch/riscv/lib/string.c > @@ -0,0 +1,90 @@ > +// 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 > +#include > + > +/* Minimum size for a word copy to be convenient */ > +#define BYTES_LONG sizeof(long) > +#define WORD_MASK (BYTES_LONG - 1) > +#define MIN_THRESHOLD (BYTES_LONG * 2) > + > +/* convenience union to avoid cast between different pointer types */ > +union types { > + u8 *as_u8; > + unsigned long *as_ulong; > + uintptr_t as_uptr; > +}; > + > +union const_types { > + const u8 *as_u8; > + unsigned long *as_ulong; > + uintptr_t as_uptr; > +}; > + > +void *__memcpy(void *dest, const void *src, size_t count) How about using __attribute__((optimize("-O2"))) here to replace your previous "#ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE"? > +{ > + union const_types s = { .as_u8 = src }; > + union types d = { .as_u8 = dest }; > + int distance = 0; > + > + if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) { > + if (count < MIN_THRESHOLD) > + goto copy_remainder; > + > + /* Copy a byte at time until destination is aligned. */ > + for (; d.as_uptr & WORD_MASK; count--) > + *d.as_u8++ = *s.as_u8++; > + > + distance = s.as_uptr & WORD_MASK; > + } > + > + if (distance) { > + unsigned long last, next; > + > + /* > + * s is distance bytes ahead of d, and d just reached > + * the alignment boundary. Move s backward to word align it > + * and shift data to compensate for distance, in order to do > + * word-by-word copy. > + */ > + s.as_u8 -= distance; > + > + next = s.as_ulong[0]; > + for (; count >= BYTES_LONG; count -= BYTES_LONG) { > + last = next; > + next = s.as_ulong[1]; > + > + d.as_ulong[0] = last >> (distance * 8) | > + next << ((BYTES_LONG - distance) * 8); > + > + d.as_ulong++; > + s.as_ulong++; > + } > + > + /* Restore s with the original offset. */ > + s.as_u8 += distance; > + } else { > + /* > + * 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.as_ulong++ = *s.as_ulong++; > + } > + > +copy_remainder: > + while (count--) > + *d.as_u8++ = *s.as_u8++; > + > + return dest; > +} > +EXPORT_SYMBOL(__memcpy); > + > +void *memcpy(void *dest, const void *src, size_t count) __weak __alias(__memcpy); > +EXPORT_SYMBOL(memcpy); > -- > 2.31.1 > -- Best Regards Guo Ren ML: https://lore.kernel.org/linux-csky/ From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9EFAAC433F5 for ; Thu, 30 Sep 2021 01:25:38 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5D83C615E5 for ; Thu, 30 Sep 2021 01:25:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 5D83C615E5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:Subject:Message-ID:Date:From: In-Reply-To:References:MIME-Version:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=bpp1CmW5lUCsdY8Qb5w+o4mEvrNj36wl/agP9g4KiEU=; b=fn+7lJVAMEts4+ sfEOrAB8lpJpkFbjAYApCCRhKryaXcFenWnS8yx2X4iNE81j5Dn+gANBk21p2liu/YwILZsVelU+y OksyDp2TEZTRKNfBFEq+3Bui462JjOuD5JAwUk2IUPlY8z2qGuQTd7n8IldjZHLeXxFYx0s2eWDqj pYNEYMasu5Ayy1GMkVozju9Cc6JRkfhDL71aVGIrQQWwg1JVDY0YggfaAadlXcQhzxFRLA7Y3RLI8 5w9GYqGinvLnDgKP62rdjcTl6hevSxjdvZ6sZIcGAq/cf9P2ZzaLbBwITk+yQAmuq+CZXRxGDcdCM VA+i0dNfJuYvmHTmgyhQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mVkot-00Ci2N-ER; Thu, 30 Sep 2021 01:25:07 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mVkom-00Ci1h-5j for linux-riscv@lists.infradead.org; Thu, 30 Sep 2021 01:25:02 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3FFC5611C0 for ; Thu, 30 Sep 2021 01:24:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1632965099; bh=9UwRNhH+QUgXvsQcSHsRIJoQjd68Bzhy/GzdrwVADlc=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=kxaMWiBvWWzwdWP6y5ScKiNQ+rgkQosRAEYFE+4JQyW2MeFx1CVAy6mH302q+A4WC 0ABkq5tC0detJXp1DDwitkPCf5eWjZ2r77QtMR9PtIlpD1QXALOHUAWmZZnYoAUq2J WDnr0zk4gTKtYAnucun3KXWYnuW2u7gR+EhmRfNyb/O6MK7/zd+gZusfuv4VgrfAxA 05QF8cqS4xYWJAWk+kbCUcBlHwGhSIs2FjZRv6PPzWmAObu6rqCvT7u0GUOn8yIEnF AwCIUhkdLGwaL2xWbeF+ltmDApMUGxvvb5WbeuKCYdLjeLsxMhu0aXHdGfMlyl6Wla PKssoHytbSqtg== Received: by mail-ua1-f51.google.com with SMTP id b34so2976615uad.8 for ; Wed, 29 Sep 2021 18:24:59 -0700 (PDT) X-Gm-Message-State: AOAM533sbjKkMaSs+w1geaF42McfsA4V/nRvoUHQGp8uZUlknw1yo0BQ AITAowG7J5SIlnxs4rf+kTGScOQdEpLP1o8LOgE= X-Google-Smtp-Source: ABdhPJxr4nyuS3T6e/1IiTSYUMT71ALIxV3VM+0ngW+OYcCbfpfRLq7KAUbH04GJbR74OsIrmP3zaH8LcVoJbV1j7Rs= X-Received: by 2002:ab0:6ec6:: with SMTP id c6mr3629624uav.97.1632965098324; Wed, 29 Sep 2021 18:24:58 -0700 (PDT) MIME-Version: 1.0 References: <20210929172234.31620-1-mcroce@linux.microsoft.com> <20210929172234.31620-2-mcroce@linux.microsoft.com> In-Reply-To: <20210929172234.31620-2-mcroce@linux.microsoft.com> From: Guo Ren Date: Thu, 30 Sep 2021 09:24:47 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v5 1/3] riscv: optimized memcpy To: Matteo Croce Cc: linux-riscv , Linux Kernel Mailing List , linux-arch , Paul Walmsley , Palmer Dabbelt , Albert Ou , Atish Patra , Emil Renner Berthing , Akira Tsukamoto , Drew Fustini , Bin Meng , David Laight , Christoph Hellwig X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210929_182500_285245_B4662178 X-CRM114-Status: GOOD ( 40.53 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Thu, Sep 30, 2021 at 1:22 AM Matteo Croce wrote: > > From: Matteo Croce > > 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 > Reported-by: kernel test robot > --- > 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 | 90 ++++++++++++++++++++++++++ > 5 files changed, 97 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 What's the problem with the -O3 & -Os? If the user uses CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 that will cause bad performance for memcpy? Seems asm version is more compatible? > #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 > -#include > - > -/* 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..bfc912ee23f8 > --- /dev/null > +++ b/arch/riscv/lib/string.c > @@ -0,0 +1,90 @@ > +// 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 > +#include > + > +/* Minimum size for a word copy to be convenient */ > +#define BYTES_LONG sizeof(long) > +#define WORD_MASK (BYTES_LONG - 1) > +#define MIN_THRESHOLD (BYTES_LONG * 2) > + > +/* convenience union to avoid cast between different pointer types */ > +union types { > + u8 *as_u8; > + unsigned long *as_ulong; > + uintptr_t as_uptr; > +}; > + > +union const_types { > + const u8 *as_u8; > + unsigned long *as_ulong; > + uintptr_t as_uptr; > +}; > + > +void *__memcpy(void *dest, const void *src, size_t count) How about using __attribute__((optimize("-O2"))) here to replace your previous "#ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE"? > +{ > + union const_types s = { .as_u8 = src }; > + union types d = { .as_u8 = dest }; > + int distance = 0; > + > + if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) { > + if (count < MIN_THRESHOLD) > + goto copy_remainder; > + > + /* Copy a byte at time until destination is aligned. */ > + for (; d.as_uptr & WORD_MASK; count--) > + *d.as_u8++ = *s.as_u8++; > + > + distance = s.as_uptr & WORD_MASK; > + } > + > + if (distance) { > + unsigned long last, next; > + > + /* > + * s is distance bytes ahead of d, and d just reached > + * the alignment boundary. Move s backward to word align it > + * and shift data to compensate for distance, in order to do > + * word-by-word copy. > + */ > + s.as_u8 -= distance; > + > + next = s.as_ulong[0]; > + for (; count >= BYTES_LONG; count -= BYTES_LONG) { > + last = next; > + next = s.as_ulong[1]; > + > + d.as_ulong[0] = last >> (distance * 8) | > + next << ((BYTES_LONG - distance) * 8); > + > + d.as_ulong++; > + s.as_ulong++; > + } > + > + /* Restore s with the original offset. */ > + s.as_u8 += distance; > + } else { > + /* > + * 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.as_ulong++ = *s.as_ulong++; > + } > + > +copy_remainder: > + while (count--) > + *d.as_u8++ = *s.as_u8++; > + > + return dest; > +} > +EXPORT_SYMBOL(__memcpy); > + > +void *memcpy(void *dest, const void *src, size_t count) __weak __alias(__memcpy); > +EXPORT_SYMBOL(memcpy); > -- > 2.31.1 > -- Best Regards Guo Ren ML: https://lore.kernel.org/linux-csky/ _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv