From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lj1-x22e.google.com (mail-lj1-x22e.google.com [IPv6:2a00:1450:4864:20::22e]) by sourceware.org (Postfix) with ESMTPS id B57C73858D1E for ; Wed, 2 Aug 2023 16:04:20 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org B57C73858D1E Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=rivosinc.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=rivosinc.com Received: by mail-lj1-x22e.google.com with SMTP id 38308e7fff4ca-2b962c226ceso106726501fa.3 for ; Wed, 02 Aug 2023 09:04:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rivosinc-com.20221208.gappssmtp.com; s=20221208; t=1690992259; x=1691597059; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=gxR3qDjTeGsUAvbbhaY8MHvFL5mt1Qp+wlBK8ORHcRY=; b=zVFWoIIYiE0Glb6b4oKyzLk5IyYwFnbY3GanumUqf+ecvOPVa9iQm8snB6YXwtWjkZ d3+cxO12FfHhWUBwlrP0FSqJy4PwCPuibh1iUny9F92GKJmI03MyDa869VVxkoZVK9ot fYJwvaUNeHANn1TdhTF/9rlKPqNAkAx9iFF8wvB2bWBKAlTMgfakzLlomLeaf8+tHAtH 9gYEe8ENnHiTl41QP6r8zEMqQ8Q6Iis51FwN+LtbqF5lhVog507R8l1GDwJLGdZfsvfg ZwdgIviPZonFzVjZcSothU+WZID8+wk4A57n0Fze79Iq9WIP06guzRX6btNy9UyJ6MW1 oz/w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690992259; x=1691597059; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=gxR3qDjTeGsUAvbbhaY8MHvFL5mt1Qp+wlBK8ORHcRY=; b=c792JQ0wP+bDkvtdbrMENxXrRB1UFk8lucfUg2IIB6kC4F+zvaE4ec+JzWgGM8IgFS gLbEgnLoxjnz9i33hOfDj1wdCZVyxts09YP7l+fQ8s3nW8/3JxBSE26YA6TkRoaNKnAT qQe0sc/f6w/+VWrVfc66QPPE8+TjxsbMmn6r8+Id2VP30meV1WUWYViQtaayGsCLAe7/ uGKoTnybCNzYC+CeaPSa+PP3d9IVryWZiEYqLHNRnK1jdlKz7TO15XPP8dFNpf86va7E 1Jvl+axsdDfqsty5yq+ePAgZZR6pb+W1Spzvd+deNI3O+LvCcU1xi3Sd4re7Qf4pSorn +Z2Q== X-Gm-Message-State: ABy/qLZWF0atIQnSVgJefjxvv3r/thbVQsdvR/s3W4JWM9Bgpvxg+R0n RtSydyWuY+iQa3BBfsjT7IEpOTf6UiabJ3kaPQxQkQBjg/zyah94 X-Google-Smtp-Source: APBJJlEtMc7+8m/fXDxEPFE6+G4dfKN01ebD+DtWxL27RdznplLNPA0A2vpvXEyO09WuOtbzKdzCv1dm/t2nWUcTNpg= X-Received: by 2002:a19:2d57:0:b0:4fe:1f02:e54b with SMTP id t23-20020a192d57000000b004fe1f02e54bmr4598540lft.56.1690992258868; Wed, 02 Aug 2023 09:04:18 -0700 (PDT) MIME-Version: 1.0 References: <20230802155903.2552780-1-evan@rivosinc.com> In-Reply-To: <20230802155903.2552780-1-evan@rivosinc.com> From: Evan Green Date: Wed, 2 Aug 2023 09:03:42 -0700 Message-ID: Subject: Re: [PATCH v6 0/5] RISC-V: ifunced memcpy using new kernel hwprobe interface To: libc-alpha@sourceware.org Cc: slewis@rivosinc.com, Florian Weimer , palmer@rivosinc.com, vineetg@rivosinc.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-3.6 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Wed, Aug 2, 2023 at 8:59=E2=80=AFAM Evan Green wrote= : > > > This series illustrates the use of a recently accepted Linux syscall that > enumerates architectural information about the RISC-V cores the system > is running on. In this series we expose a small wrapper function around > the syscall. An ifunc selector for memcpy queries it to see if unaligned > access is "fast" on this hardware. If it is, it selects a newly provided > implementation of memcpy that doesn't work hard at aligning the src and > destination buffers. > > For applications and libraries outside of glibc that want to use > __riscv_hwprobe() in ifunc selectors, this series also introduces > __riscv_hwprobe_early(), which works correctly even before all symbols > have been resolved. Minor correction: This paragraph above is stale. In this series I implemented Florian's suggestion of passing a pointer to __riscv_hwprobe as a second argument to ifunc selectors. It works well, except it requires a little bit of libc-symbols.h macro rearranging to allow something like libc_ifunc() to handle multiple arguments. You'll see that in a new patch within this series. > > The memcpy implementation is independent enough from the rest of the > series that it can be omitted safely if desired. > > Performance numbers were compared using a small test program [1], run on > a D1 Nezha board, which supports fast unaligned access. "Fast" here > means copying unaligned words is faster than copying byte-wise, but > still slower than copying aligned words. Here's the speed of various > memcpy()s with the generic implementation. The numbers before are using > v4's memcpy implementation, with the "copy last byte via overlapping > misaligned word" fix this should get even better, though I'm having > trouble with my setup right now and wasn't able to re-run the numbers > on the same hardware. I'll keep working on that. > > memcpy size 1 count 1000000 offset 0 took 109564 us > memcpy size 3 count 1000000 offset 0 took 138425 us > memcpy size 4 count 1000000 offset 0 took 148374 us > memcpy size 7 count 1000000 offset 0 took 178433 us > memcpy size 8 count 1000000 offset 0 took 188430 us > memcpy size f count 1000000 offset 0 took 266118 us > memcpy size f count 1000000 offset 1 took 265940 us > memcpy size f count 1000000 offset 3 took 265934 us > memcpy size f count 1000000 offset 7 took 266215 us > memcpy size f count 1000000 offset 8 took 265954 us > memcpy size f count 1000000 offset 9 took 265886 us > memcpy size 10 count 1000000 offset 0 took 195308 us > memcpy size 11 count 1000000 offset 0 took 205161 us > memcpy size 17 count 1000000 offset 0 took 274376 us > memcpy size 18 count 1000000 offset 0 took 199188 us > memcpy size 19 count 1000000 offset 0 took 209258 us > memcpy size 1f count 1000000 offset 0 took 278263 us > memcpy size 20 count 1000000 offset 0 took 207364 us > memcpy size 21 count 1000000 offset 0 took 217143 us > memcpy size 3f count 1000000 offset 0 took 300023 us > memcpy size 40 count 1000000 offset 0 took 231063 us > memcpy size 41 count 1000000 offset 0 took 241259 us > memcpy size 7c count 100000 offset 0 took 32807 us > memcpy size 7f count 100000 offset 0 took 36274 us > memcpy size ff count 100000 offset 0 took 47818 us > memcpy size ff count 100000 offset 0 took 47932 us > memcpy size 100 count 100000 offset 0 took 40468 us > memcpy size 200 count 100000 offset 0 took 64245 us > memcpy size 27f count 100000 offset 0 took 82549 us > memcpy size 400 count 100000 offset 0 took 111254 us > memcpy size 407 count 100000 offset 0 took 119364 us > memcpy size 800 count 100000 offset 0 took 203899 us > memcpy size 87f count 100000 offset 0 took 222465 us > memcpy size 87f count 100000 offset 3 took 222289 us > memcpy size 1000 count 100000 offset 0 took 388846 us > memcpy size 1000 count 100000 offset 1 took 468827 us > memcpy size 1000 count 100000 offset 3 took 397098 us > memcpy size 1000 count 100000 offset 4 took 397379 us > memcpy size 1000 count 100000 offset 5 took 397368 us > memcpy size 1000 count 100000 offset 7 took 396867 us > memcpy size 1000 count 100000 offset 8 took 389227 us > memcpy size 1000 count 100000 offset 9 took 395949 us > memcpy size 3000 count 50000 offset 0 took 674837 us > memcpy size 3000 count 50000 offset 1 took 676944 us > memcpy size 3000 count 50000 offset 3 took 679709 us > memcpy size 3000 count 50000 offset 4 took 680829 us > memcpy size 3000 count 50000 offset 5 took 678024 us > memcpy size 3000 count 50000 offset 7 took 681097 us > memcpy size 3000 count 50000 offset 8 took 670004 us > memcpy size 3000 count 50000 offset 9 took 674553 us > > Here is that same test run with the assembly memcpy() in this series: > memcpy size 1 count 1000000 offset 0 took 92703 us > memcpy size 3 count 1000000 offset 0 took 112527 us > memcpy size 4 count 1000000 offset 0 took 120481 us > memcpy size 7 count 1000000 offset 0 took 149558 us > memcpy size 8 count 1000000 offset 0 took 90617 us > memcpy size f count 1000000 offset 0 took 174373 us > memcpy size f count 1000000 offset 1 took 178615 us > memcpy size f count 1000000 offset 3 took 178845 us > memcpy size f count 1000000 offset 7 took 178636 us > memcpy size f count 1000000 offset 8 took 174442 us > memcpy size f count 1000000 offset 9 took 178660 us > memcpy size 10 count 1000000 offset 0 took 99845 us > memcpy size 11 count 1000000 offset 0 took 112522 us > memcpy size 17 count 1000000 offset 0 took 179735 us > memcpy size 18 count 1000000 offset 0 took 110870 us > memcpy size 19 count 1000000 offset 0 took 121472 us > memcpy size 1f count 1000000 offset 0 took 188231 us > memcpy size 20 count 1000000 offset 0 took 119571 us > memcpy size 21 count 1000000 offset 0 took 132429 us > memcpy size 3f count 1000000 offset 0 took 227021 us > memcpy size 40 count 1000000 offset 0 took 166416 us > memcpy size 41 count 1000000 offset 0 took 180206 us > memcpy size 7c count 100000 offset 0 took 28602 us > memcpy size 7f count 100000 offset 0 took 31676 us > memcpy size ff count 100000 offset 0 took 39257 us > memcpy size ff count 100000 offset 0 took 39176 us > memcpy size 100 count 100000 offset 0 took 21928 us > memcpy size 200 count 100000 offset 0 took 35814 us > memcpy size 27f count 100000 offset 0 took 60315 us > memcpy size 400 count 100000 offset 0 took 63652 us > memcpy size 407 count 100000 offset 0 took 73160 us > memcpy size 800 count 100000 offset 0 took 121532 us > memcpy size 87f count 100000 offset 0 took 147269 us > memcpy size 87f count 100000 offset 3 took 144744 us > memcpy size 1000 count 100000 offset 0 took 232057 us > memcpy size 1000 count 100000 offset 1 took 254319 us > memcpy size 1000 count 100000 offset 3 took 256973 us > memcpy size 1000 count 100000 offset 4 took 257655 us > memcpy size 1000 count 100000 offset 5 took 259456 us > memcpy size 1000 count 100000 offset 7 took 260849 us > memcpy size 1000 count 100000 offset 8 took 232347 us > memcpy size 1000 count 100000 offset 9 took 254330 us > memcpy size 3000 count 50000 offset 0 took 382376 us > memcpy size 3000 count 50000 offset 1 took 389872 us > memcpy size 3000 count 50000 offset 3 took 385310 us > memcpy size 3000 count 50000 offset 4 took 389748 us > memcpy size 3000 count 50000 offset 5 took 391707 us > memcpy size 3000 count 50000 offset 7 took 386778 us > memcpy size 3000 count 50000 offset 8 took 385691 us > memcpy size 3000 count 50000 offset 9 took 392030 us > > The assembly routine is measurably better. > > [1] https://pastebin.com/DRyECNQW > > > Changes in v6: > - Prefixed __riscv_hwprobe() parameters names with __ to avoid user > macro namespace pollution (Joseph) > - Introduced riscv-ifunc.h for multi-arg ifunc selectors. > - Fix a couple regressions in the assembly from v5 :/ > - Use passed hwprobe pointer in memcpy ifunc selector. > > Changes in v5: > - Do unaligned word access for final trailing bytes (Richard) > > Changes in v4: > - Remove __USE_GNU (Florian) > - __nonnull, __wur, __THROW, and __fortified_attr_access decorations > (Florian) > - change long to long int (Florian) > - Fix comment formatting (Florian) > - Update backup kernel header content copy. > - Fix function declaration formatting (Florian) > - Changed export versions to 2.38 > - Fixed comment style (Florian) > > Changes in v3: > - Update argument types to match v4 kernel interface > - Add the "return" to the vsyscall > - Fix up vdso arg types to match kernel v4 version > - Remove ifdef around INLINE_VSYSCALL (Adhemerval) > - Word align dest for large memcpy()s. > - Add tags > - Remove spurious blank line from sysdeps/riscv/memcpy.c > > Changes in v2: > - hwprobe.h: Use __has_include and duplicate Linux content to make > compilation work when Linux headers are absent (Adhemerval) > - hwprobe.h: Put declaration under __USE_GNU (Adhemerval) > - Use INLINE_SYSCALL_CALL (Adhemerval) > - Update versions > - Update UNALIGNED_MASK to match kernel v3 series. > - Add vDSO interface > - Used _MASK instead of _FAST value itself. > > Evan Green (5): > riscv: Add Linux hwprobe syscall support > riscv: Add hwprobe vdso call support > riscv: Add __riscv_hwprobe pointer to ifunc calls > riscv: Enable multi-arg ifunc resolvers > riscv: Add and use alignment-ignorant memcpy > > include/libc-symbols.h | 28 ++-- > sysdeps/riscv/dl-irel.h | 8 +- > sysdeps/riscv/memcopy.h | 26 ++++ > sysdeps/riscv/memcpy.c | 66 +++++++++ > sysdeps/riscv/memcpy_noalignment.S | 138 ++++++++++++++++++ > sysdeps/riscv/riscv-ifunc.h | 27 ++++ > sysdeps/unix/sysv/linux/dl-vdso-setup.c | 10 ++ > sysdeps/unix/sysv/linux/dl-vdso-setup.h | 3 + > sysdeps/unix/sysv/linux/riscv/Makefile | 8 +- > sysdeps/unix/sysv/linux/riscv/Versions | 3 + > sysdeps/unix/sysv/linux/riscv/hwprobe.c | 32 ++++ > .../unix/sysv/linux/riscv/memcpy-generic.c | 24 +++ > .../unix/sysv/linux/riscv/rv32/libc.abilist | 1 + > .../unix/sysv/linux/riscv/rv64/libc.abilist | 1 + > sysdeps/unix/sysv/linux/riscv/sys/hwprobe.h | 82 +++++++++++ > sysdeps/unix/sysv/linux/riscv/sysdep.h | 1 + > 16 files changed, 441 insertions(+), 17 deletions(-) > create mode 100644 sysdeps/riscv/memcopy.h > create mode 100644 sysdeps/riscv/memcpy.c > create mode 100644 sysdeps/riscv/memcpy_noalignment.S > create mode 100644 sysdeps/riscv/riscv-ifunc.h > create mode 100644 sysdeps/unix/sysv/linux/riscv/hwprobe.c > create mode 100644 sysdeps/unix/sysv/linux/riscv/memcpy-generic.c > create mode 100644 sysdeps/unix/sysv/linux/riscv/sys/hwprobe.h > > -- > 2.34.1 >