From: Sunil Pandey <skpgkp2@gmail.com>
To: Noah Goldstein <goldstein.w.n@gmail.com>, libc-stable@sourceware.org
Cc: "H.J. Lu" <hjl.tools@gmail.com>,
GNU C Library <libc-alpha@sourceware.org>
Subject: Re: [PATCH v2] x86: Set rep_movsb_threshold to 2112 on processors with FSRM
Date: Wed, 27 Apr 2022 16:56:34 -0700 [thread overview]
Message-ID: <CAMAf5_e_au9vxhcX69sODVQMQCho+0v1BUPjujWZaEjshya3Hg@mail.gmail.com> (raw)
In-Reply-To: <CAFUsyfLU-y3FAnSnVjeyO4ZxGV9kwoAugJvVppP9dS-X2W_aQw@mail.gmail.com>
On Sat, May 1, 2021 at 12:47 PM Noah Goldstein via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> On Sat, May 1, 2021 at 10:09 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > On Fri, Apr 30, 2021 at 6:26 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> > >
> > > 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.
> > >
> >
> > This is the v2 patch I am checking in next week.
>
> Sorry! LGTM. Change is a big net gain :)
>
> >
> > Thanks.
> >
> > --
> > H.J.
I would like to backport this patch to release branches.
Any comments or objections?
--Sunil
parent reply other threads:[~2022-04-27 23:57 UTC|newest]
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