Date: Mon, 7 Aug 2023 02:14:57 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Robert Clausecker <fuz@freebsd.org> Cc: src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: 61f4c4d3dd38 - main - lib/libc/amd64/string: add strchrnul implementations (scalar, baseline) Message-ID: <ZNApcX0nJCryu89o@kib.kiev.ua> In-Reply-To: <202308061410.376EA6WM096467@gitrepo.freebsd.org> References: <202308061410.376EA6WM096467@gitrepo.freebsd.org>
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On Sun, Aug 06, 2023 at 02:10:06PM +0000, Robert Clausecker wrote: > The branch main has been updated by fuz: > > URL: https://cgit.FreeBSD.org/src/commit/?id=61f4c4d3dd38c5b79e04fff1dedb02071ebb33f2 > > commit 61f4c4d3dd38c5b79e04fff1dedb02071ebb33f2 > Author: Robert Clausecker <fuz@FreeBSD.org> > AuthorDate: 2023-06-30 14:45:11 +0000 > Commit: Robert Clausecker <fuz@FreeBSD.org> > CommitDate: 2023-08-06 13:58:27 +0000 > > lib/libc/amd64/string: add strchrnul implementations (scalar, baseline) > > A lot better than the generic (pre) implementaion. We do not beat glibc > for long strings, likely due to glibc switching to AVX once the input is > sufficiently long. X86-64-v3 and v4 implementations may be added at a > future time. > > os: FreeBSD > arch: amd64 > cpu: 11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz > │ strchrnul_pre.out │ strchrnul_scalar.out │ strchrnul_baseline.out │ > │ sec/op │ sec/op vs base │ sec/op vs base │ > Short 129.68µ ± 3% 59.91µ ± 1% -53.80% (p=0.000 n=20) 44.37µ ± 1% -65.79% (p=0.000 n=20) > Mid 21.15µ ± 0% 19.30µ ± 0% -8.76% (p=0.000 n=20) 12.30µ ± 0% -41.85% (p=0.000 n=20) > Long 13.772µ ± 0% 11.028µ ± 0% -19.92% (p=0.000 n=20) 3.285µ ± 0% -76.15% (p=0.000 n=20) > geomean 33.55µ 23.36µ -30.37% 12.15µ -63.80% > > │ strchrnul_pre.out │ strchrnul_scalar.out │ strchrnul_baseline.out │ > │ B/s │ B/s vs base │ B/s vs base │ > Short 919.3Mi ± 3% 1989.7Mi ± 1% +116.45% (p=0.000 n=20) 2686.8Mi ± 1% +192.28% (p=0.000 n=20) > Mid 5.505Gi ± 0% 6.033Gi ± 0% +9.60% (p=0.000 n=20) 9.466Gi ± 0% +71.97% (p=0.000 n=20) > Long 8.453Gi ± 0% 10.557Gi ± 0% +24.88% (p=0.000 n=20) 35.441Gi ± 0% +319.26% (p=0.000 n=20) > geomean 3.470Gi 4.983Gi +43.62% 9.584Gi +176.22% > > For comparison, glibc on the same machine: > > │ strchrnul_glibc.out │ > │ sec/op │ > Short 49.73µ ± 0% > Mid 14.60µ ± 0% > Long 1.237µ ± 0% > geomean 9.646µ > > │ strchrnul_glibc.out │ > │ B/s │ > Short 2.341Gi ± 0% > Mid 7.976Gi ± 0% > Long 94.14Gi ± 0% > geomean 12.07Gi > > Sponsored by: The FreeBSD Foundation > Approved by: mjg > Differential Revision: https://reviews.freebsd.org/D41333 > --- > lib/libc/amd64/string/Makefile.inc | 1 + > lib/libc/amd64/string/strchrnul.S | 167 +++++++++++++++++++++++++++++++++++++ > 2 files changed, 168 insertions(+) > > diff --git a/lib/libc/amd64/string/Makefile.inc b/lib/libc/amd64/string/Makefile.inc > index 1bfefa7be98c..b5260cfd78d1 100644 > --- a/lib/libc/amd64/string/Makefile.inc > +++ b/lib/libc/amd64/string/Makefile.inc > @@ -8,6 +8,7 @@ MDSRCS+= \ > memmove.S \ > memset.S \ > strcat.S \ > + strchrnul.S \ > strcmp.S \ > strlen.S \ > stpcpy.S > diff --git a/lib/libc/amd64/string/strchrnul.S b/lib/libc/amd64/string/strchrnul.S > new file mode 100644 > index 000000000000..6d22f31850f8 > --- /dev/null > +++ b/lib/libc/amd64/string/strchrnul.S > @@ -0,0 +1,167 @@ > +/*- > + * Copyright (c) 2023 The FreeBSD Foundation > + * > + * This software was developed by Robert Clausecker <fuz@FreeBSD.org> > + * under sponsorship from the FreeBSD Foundation. > + * > + * Redistribution and use in source and binary forms, with or without > + * modification, are permitted provided that the following conditions > + * are met: > + * 1. Redistributions of source code must retain the above copyright > + * notice, this list of conditions and the following disclaimer. > + * 2. Redistributions in binary form must reproduce the above copyright > + * notice, this list of conditions and the following disclaimer in the > + * documentation and/or other materials provided with the distribution. > + * > + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ''AS IS'' AND > + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE > + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE > + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE > + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL > + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS > + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) > + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT > + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY > + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF > + * SUCH DAMAGE > + */ > + > +#include <machine/asm.h> > + > +#include "amd64_archlevel.h" > + > +#define ALIGN_TEXT .p2align 4,0x90 # 16-byte alignment, nop-filled > + > + .weak strchrnul > + .set strchrnul, __strchrnul > + > +ARCHFUNCS(__strchrnul) > + ARCHFUNC(__strchrnul, scalar) > + ARCHFUNC(__strchrnul, baseline) > +ENDARCHFUNCS(__strchrnul) ... > +1: sub $8, %rdi # undo advance past buffer > +2: tzcnt %rax, %rax # first NUL or c byte match tzcnt is the _V3 feature, while __strchrnul_scalar seems to be used for _V2. Am I missing something?
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