From: "H.J. Lu" <hjl.tools@gmail.com>
To: Noah Goldstein <goldstein.w.n@gmail.com>
Cc: GNU C Library <libc-alpha@sourceware.org>
Subject: Re: [PATCH] x86: Set rep_movsb_threshold to 2112 on processors with FSRM
Date: Fri, 30 Apr 2021 18:26:43 -0700 [thread overview]
Message-ID: <CAMe9rOpRHGYJ=9-WCONL-YxcaVEGcR7jRQTRUPTpQRRv6bKZOQ@mail.gmail.com> (raw)
In-Reply-To: <CAFUsyf+1=2hPNOth42pspXfGueGSpyHWY09ZP3xdJDW5KRnLcw@mail.gmail.com>
On Fri, Apr 30, 2021 at 5:17 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> On Fri, Apr 30, 2021 at 4:51 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > On Fri, Apr 30, 2021 at 3:59 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> > >
> > > On Fri, Apr 30, 2021 at 4:43 PM H.J. Lu via Libc-alpha
> > > <libc-alpha@sourceware.org> wrote:
> > > >
> > > > The glibc memcpy benchmark on Intel Core i7-1065G7 (Ice Lake) showed
> > > > that REP MOVSB became faster after 2112 bytes:
> > > >
> > > > Vector + REP MOVSB REP MOVSB
> > > > length=2112, align1=0, align2=0: 24.20 24.40
> > > > length=2112, align1=1, align2=0: 26.07 23.13
> > > > length=2112, align1=0, align2=1: 27.18 28.13
> > > > length=2112, align1=1, align2=1: 26.23 25.16
> > > > length=2176, align1=0, align2=0: 23.18 22.52
> > > > length=2176, align1=2, align2=0: 25.45 22.52
> > > > length=2176, align1=0, align2=2: 27.14 27.82
> > > > length=2176, align1=2, align2=2: 22.73 25.56
> > > > length=2240, align1=0, align2=0: 24.62 24.25
> > > > length=2240, align1=3, align2=0: 29.77 27.15
> > > > length=2240, align1=0, align2=3: 35.55 29.93
> > > > length=2240, align1=3, align2=3: 34.49 25.15
> > > > length=2304, align1=0, align2=0: 34.75 26.64
> > > > length=2304, align1=4, align2=0: 32.09 22.63
> > > > length=2304, align1=0, align2=4: 28.43 31.24
> > > >
> > >
> > > Do you know what is happening at:
> > > length=2304, align1=0, align2=4: 28.43 31.24
> > >
> > > Seems align2 > align1 gets worse for larger sizes as well.
> > >
> > > I.e from my Icelake (1 run):
> > > w/o
> > > Patch w/ Patch
> > > length=3648, align1=0, align2=25: 72.91 83.99
> > > length=3712, align1=0, align2=26: 72.52 84.92
> > > length=3776, align1=0, align2=27: 76.16 84.02
> > > length=3840, align1=0, align2=28: 75.44 90.13
> > > length=3904, align1=0, align2=29: 81.62 84.43
> > > length=3968, align1=0, align2=30: 76.82 93.39
> > > length=4032, align1=0, align2=31: 80.01 89.89
> > > length=4096, align1=0, align2=32: 72.89 97.50
> >
> > On Intel Core i7-1165G7 (Tiger Lake), I got
>
> Where the original numbers icl or tgl? But was just wondering
Here are numbers on Core i7-1065G7 (Ice Lake):
__memcpy_evex_unaligned_erms __memcpy_erms
length=2048, align1=0, align2=0: 21.51 22.52
length=2048, align1=0, align2=0: 22.11 21.50
length=2048, align1=0, align2=0: 21.96 22.10
length=2048, align1=0, align2=0: 22.58 21.51
length=2112, align1=0, align2=0: 24.20 24.40
length=2112, align1=1, align2=0: 26.07 23.13
length=2112, align1=0, align2=1: 27.18 28.13
length=2112, align1=1, align2=1: 26.23 25.16
length=2176, align1=0, align2=0: 23.18 22.52
length=2176, align1=2, align2=0: 25.45 22.52
length=2176, align1=0, align2=2: 27.14 35.82
length=2176, align1=2, align2=2: 22.73 25.56
length=2240, align1=0, align2=0: 24.62 24.25
length=2240, align1=3, align2=0: 29.77 27.15
length=2240, align1=0, align2=3: 35.55 29.93
length=2240, align1=3, align2=3: 34.49 25.15
length=2304, align1=0, align2=0: 34.75 26.64
length=2304, align1=4, align2=0: 32.09 22.63
length=2304, align1=0, align2=4: 28.43 31.24
length=2304, align1=4, align2=4: 23.95 25.56
length=2368, align1=0, align2=0: 25.57 24.34
length=2368, align1=5, align2=0: 30.57 23.94
length=2368, align1=0, align2=5: 31.29 31.24
length=2368, align1=5, align2=5: 25.57 26.69
length=2432, align1=0, align2=0: 25.16 23.77
length=2432, align1=6, align2=0: 29.27 23.13
length=2432, align1=0, align2=6: 30.40 33.77
length=2432, align1=6, align2=6: 25.16 26.37
length=2496, align1=0, align2=0: 26.85 24.34
length=2496, align1=7, align2=0: 32.04 24.75
length=2496, align1=0, align2=7: 32.70 33.06
length=2496, align1=7, align2=7: 26.79 25.97
length=2560, align1=0, align2=0: 61.84 23.53
length=2560, align1=8, align2=0: 30.74 23.53
length=2560, align1=0, align2=8: 33.35 35.44
length=2560, align1=8, align2=8: 27.94 27.52
length=2624, align1=0, align2=0: 27.60 24.75
length=2624, align1=9, align2=0: 33.28 25.16
length=2624, align1=0, align2=9: 34.14 34.48
length=2624, align1=9, align2=9: 28.00 26.78
length=2688, align1=0, align2=0: 38.94 24.61
length=2688, align1=10, align2=0: 31.23 23.94
length=2688, align1=0, align2=10: 33.89 37.11
length=2688, align1=10, align2=10: 28.40 27.18
length=2752, align1=0, align2=0: 36.17 25.56
length=2752, align1=11, align2=0: 35.88 25.57
length=2752, align1=0, align2=11: 35.40 36.11
length=2752, align1=11, align2=11: 28.82 27.94
length=2816, align1=0, align2=0: 33.78 24.54
length=2816, align1=12, align2=0: 33.75 25.96
length=2816, align1=0, align2=12: 34.24 37.73
length=2816, align1=12, align2=12: 29.22 27.59
length=2880, align1=0, align2=0: 39.76 25.97
length=2880, align1=13, align2=0: 41.26 26.66
length=2880, align1=0, align2=13: 40.72 37.73
length=2880, align1=13, align2=13: 35.13 27.59
length=2944, align1=0, align2=0: 32.09 24.75
length=2944, align1=14, align2=0: 40.27 26.78
length=2944, align1=0, align2=14: 45.59 39.55
length=2944, align1=14, align2=14: 40.94 28.00
length=3008, align1=0, align2=0: 42.17 25.97
length=3008, align1=15, align2=0: 41.81 27.07
length=3008, align1=0, align2=15: 42.67 39.35
length=3008, align1=15, align2=15: 42.18 28.00
length=3072, align1=0, align2=0: 34.71 25.16
length=3072, align1=16, align2=0: 43.31 26.37
length=3072, align1=0, align2=16: 43.41 40.98
length=3072, align1=16, align2=16: 36.62 27.99
length=3136, align1=0, align2=0: 45.75 26.78
length=3136, align1=17, align2=0: 43.29 27.59
length=3136, align1=0, align2=17: 44.44 41.16
length=3136, align1=17, align2=17: 34.99 28.59
length=3200, align1=0, align2=0: 43.12 25.16
length=3200, align1=18, align2=0: 43.04 27.59
length=3200, align1=0, align2=18: 45.08 42.59
length=3200, align1=18, align2=18: 36.00 28.81
length=3264, align1=0, align2=0: 43.01 27.48
length=3264, align1=19, align2=0: 47.72 28.61
length=3264, align1=0, align2=19: 47.00 42.60
length=3264, align1=19, align2=19: 44.44 28.81
length=3328, align1=0, align2=0: 35.50 25.75
length=3328, align1=20, align2=0: 44.84 27.19
length=3328, align1=0, align2=20: 46.38 44.41
length=3328, align1=20, align2=20: 33.68 28.81
length=3392, align1=0, align2=0: 43.82 27.18
length=3392, align1=21, align2=0: 45.91 28.81
length=3392, align1=0, align2=21: 47.61 43.06
length=3392, align1=21, align2=21: 43.82 29.21
length=3456, align1=0, align2=0: 43.83 26.64
length=3456, align1=22, align2=0: 44.77 29.49
length=3456, align1=0, align2=22: 47.57 46.01
length=3456, align1=22, align2=22: 44.11 29.62
length=3520, align1=0, align2=0: 45.04 27.99
length=3520, align1=23, align2=0: 46.59 30.55
length=3520, align1=0, align2=23: 50.58 44.80
length=3520, align1=23, align2=23: 43.85 29.21
length=3584, align1=0, align2=0: 45.04 26.88
length=3584, align1=24, align2=0: 47.22 29.21
length=3584, align1=0, align2=24: 50.12 47.47
length=3584, align1=24, align2=24: 45.04 29.80
length=3648, align1=0, align2=0: 47.13 28.40
length=3648, align1=25, align2=0: 48.78 30.94
length=3648, align1=0, align2=25: 49.25 61.42
length=3648, align1=25, align2=25: 45.85 30.02
length=3712, align1=0, align2=0: 47.24 27.19
length=3712, align1=26, align2=0: 48.41 30.79
length=3712, align1=0, align2=26: 49.65 51.57
length=3712, align1=26, align2=26: 48.76 30.33
length=3776, align1=0, align2=0: 47.35 34.61
length=3776, align1=27, align2=0: 49.16 31.99
length=3776, align1=0, align2=27: 52.06 49.38
length=3776, align1=27, align2=27: 47.36 30.43
length=3840, align1=0, align2=0: 49.70 28.35
length=3840, align1=28, align2=0: 50.29 31.81
length=3840, align1=0, align2=28: 51.15 50.71
length=3840, align1=28, align2=28: 47.07 31.65
length=3904, align1=0, align2=0: 48.28 29.21
length=3904, align1=29, align2=0: 51.96 32.99
length=3904, align1=0, align2=29: 53.24 50.71
length=3904, align1=29, align2=29: 47.88 31.64
length=3968, align1=0, align2=0: 47.89 29.19
length=3968, align1=30, align2=0: 51.52 32.57
length=3968, align1=0, align2=30: 54.03 52.33
length=3968, align1=30, align2=30: 46.62 33.15
length=4032, align1=0, align2=0: 49.77 29.62
length=4032, align1=31, align2=0: 53.62 34.27
length=4032, align1=0, align2=31: 56.44 52.33
length=4032, align1=31, align2=31: 48.94 33.16
length=4096, align1=0, align2=0: 49.37 29.21
length=4096, align1=32, align2=0: 50.46 33.00
length=4096, align1=0, align2=32: 49.31 55.14
length=4096, align1=32, align2=32: 49.28 33.05
> if the align2 != 0, align1 = 0 case on Icelake warranted more investigation.
> That being said the change is a clear winner on Icelake as well
> for any other alignment schema.
True, REP MOVSB is more efficient.
> >
> > Vector
> > REP MOVSB
> > length=2112, align1=0, align2=1: 45.21 43.69
> > length=2176, align1=0, align2=2: 45.20 45.82
> > length=2240, align1=0, align2=3: 53.46 51.41
> > length=2304, align1=0, align2=4: 47.65 48.28
> > length=2368, align1=0, align2=5: 50.10 48.27
> > length=2432, align1=0, align2=6: 50.10 50.70
> > length=2496, align1=0, align2=7: 52.54 50.71
> > length=2560, align1=0, align2=8: 52.83 53.15
> > length=2624, align1=0, align2=9: 64.98 53.15
> > length=2688, align1=0, align2=10: 54.98 55.59
> > length=2752, align1=0, align2=11: 57.43 55.59
> > length=2816, align1=0, align2=12: 57.87 58.03
> > length=2880, align1=0, align2=13: 61.97 58.03
> > length=2944, align1=0, align2=14: 71.97 60.79
> > length=3008, align1=0, align2=15: 65.02 60.47
> > length=3072, align1=0, align2=16: 65.39 63.23
> > length=3136, align1=0, align2=17: 72.54 62.92
> > length=3200, align1=0, align2=18: 69.91 65.39
> > length=3264, align1=0, align2=19: 73.38 65.39
> > length=3328, align1=0, align2=20: 73.50 67.81
> > length=3392, align1=0, align2=21: 76.81 67.81
> > length=3456, align1=0, align2=22: 76.88 70.79
> > length=3520, align1=0, align2=23: 80.30 71.07
> > length=3584, align1=0, align2=24: 80.25 72.69
> > length=3648, align1=0, align2=25: 84.58 73.01
> > length=3712, align1=0, align2=26: 85.02 75.13
> > length=3776, align1=0, align2=27: 87.51 75.14
> > length=3840, align1=0, align2=28: 87.20 77.67
> > length=3904, align1=0, align2=29: 89.82 77.99
> > length=3968, align1=0, align2=30: 102.59 80.45
> > length=4032, align1=0, align2=31: 92.38 80.60
> > length=4096, align1=0, align2=32: 85.69 84.69
> >
> > REP MOVSB is a little bit faster.
> >
> > > > Use REP MOVSB for data size > 2112 bytes in memcpy on processors with
> > > > fast short REP MOVSB (FSRM).
> > > >
> > > > * sysdeps/x86/dl-cacheinfo.h (dl_init_cacheinfo): Set
> > > > rep_movsb_threshold to 2112 on processors with fast short REP
> > > > MOVSB (FSRM).
> > > > ---
> > > > sysdeps/x86/dl-cacheinfo.h | 10 ++++++++--
> > > > 1 file changed, 8 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/sysdeps/x86/dl-cacheinfo.h b/sysdeps/x86/dl-cacheinfo.h
> > > > index d9944250fc..3f04fb5019 100644
> > > > --- a/sysdeps/x86/dl-cacheinfo.h
> > > > +++ b/sysdeps/x86/dl-cacheinfo.h
> > > > @@ -871,7 +871,10 @@ dl_init_cacheinfo (struct cpu_features *cpu_features)
> > > > if (CPU_FEATURE_USABLE_P (cpu_features, AVX512F)
> > > > && !CPU_FEATURE_PREFERRED_P (cpu_features, Prefer_No_AVX512))
> > > > {
> > > > - rep_movsb_threshold = 2048 * (64 / 16);
> > > > + if (CPU_FEATURE_USABLE_P (cpu_features, FSRM))
> > > > + rep_movsb_threshold = 2112;
> > > > + else
> > > > + rep_movsb_threshold = 2048 * (64 / 16);
> > > > #if HAVE_TUNABLES
> > > > minimum_rep_movsb_threshold = 64 * 8;
> > > > #endif
> > > > @@ -879,7 +882,10 @@ dl_init_cacheinfo (struct cpu_features *cpu_features)
> > > > else if (CPU_FEATURE_PREFERRED_P (cpu_features,
> > > > AVX_Fast_Unaligned_Load))
> > > > {
> > > > - rep_movsb_threshold = 2048 * (32 / 16);
> > > > + if (CPU_FEATURE_USABLE_P (cpu_features, FSRM))
> > > > + rep_movsb_threshold = 2112;
> > > > + else
> > > > + rep_movsb_threshold = 2048 * (32 / 16);
> > > > #if HAVE_TUNABLES
> > > > minimum_rep_movsb_threshold = 32 * 8;
> > > > #endif
> > > > --
> > > > 2.31.1
> > > >
> >
> >
> >
> > --
> > H.J.
--
H.J.
next prev parent reply other threads:[~2021-05-01 1:27 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-30 18:24 H.J. Lu
2021-04-30 22:59 ` Noah Goldstein
2021-04-30 23:50 ` H.J. Lu
2021-05-01 0:17 ` Noah Goldstein
2021-05-01 1:26 ` H.J. Lu [this message]
2021-05-01 14:08 ` [PATCH v2] " H.J. Lu
2021-05-01 18:45 ` Noah Goldstein
2022-04-27 23:56 ` Sunil Pandey
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