Thanks for all the nice inputs!

I'd appreciate an effort to bring more optimized routines to the
kernel/libc/etc.

On 29/11/24(Fri) 23:08, Mark Kettenis wrote:
> > From: Mateusz Guzik <mjguzik@gmail.com>
> > Date: Fri, 29 Nov 2024 02:01:45 +0100
> > 
> > The rep-prefixed cmps is incredibly slow even on modern CPUs.
> > 
> > The new implementation uses regular cmp to do it.
> > 
> > The code got augmented to account for retguard, otherwise it matches FreeBSD.
> > 
> > On Sapphire Rapids open1 (open + close in a loop) from will-it-scale (ops/s):
> > before:	436177
> > after:	464670 (+6.5%)
> 
> That is a nice speedup, but you'd need to present more than a single
> microbenchmark on a single microarchitecture to convince me that this
> is worth the extra complication of the assembly code.

Here are numbers from my favorite microbenchmark, on a 24 CPUs
ThinkCentre M90s Gen 5, dmesg below.

vanilla
=======
kernel		1m07.05s real     8m37.97s user     6m14.12s system
libLLVM		12m41.54s real   195m02.44s user    80m11.87s system

with memcpy
===========
kernel		1m00.66s real     8m28.24s user     5m56.32s system
libLLVM		12m27.16s real   193m46.84s user    75m29.95s system


OpenBSD 7.6-current (GENERIC.MP) #31: Sat Nov 30 14:52:25 CET 2024
    root@caju.grenadille.net:/sys/arch/amd64/compile/GENERIC.MP
real mem = 33942417408 (32370MB)
avail mem = 32635703296 (31123MB)
random: good seed from bootblocks
mpath0 at root
scsibus0 at mpath0: 256 targets
mainbus0 at root
bios0 at mainbus0: SMBIOS rev. 3.6 @ 0x71357000 (102 entries)
bios0: vendor LENOVO version "M4SKT67A" date 05/13/2024
bios0: LENOVO 12V4CTO1WW
efi0 at bios0: UEFI 2.8
efi0: American Megatrends rev 0x5001b
acpi0 at bios0: ACPI 6.5
acpi0: sleep states S0 S3 S4 S5
acpi0: tables DSDT FACP SSDT FIDT SSDT SSDT SSDT SSDT SSDT HPET APIC MCFG SSDT UEFI NHLT LPIT SSDT SSDT DBGP DBG2 SSDT DMAR FPDT SSDT SSDT BGRT LUFT TPM2 PHAT ASF! WSMT
acpi0: wakeup devices PEG1(S4) PEGP(S4) PEGP(S4) PEGP(S4) SIO1(S3) RP09(S4) PXSX(S4) RP10(S4) PXSX(S4) RP11(S4) PXSX(S4) RP12(S4) PXSX(S4) RP13(S4) PXSX(S4) RP14(S4) [...]
acpitimer0 at acpi0: 3579545 Hz, 24 bits
acpihpet0 at acpi0: 19200000 Hz
acpimadt0 at acpi0 addr 0xfee00000: PC-AT compat
cpu0 at mainbus0: apid 0 (boot processor)
cpu0: Intel(R) Core(TM) i9-14900, 5488.56 MHz, 06-b7-01, patch 0000012b
cpu0: cpuid 1 edx=bfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE> ecx=77fafbff<SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,SDBG,FMA3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,x2APIC,MOVBE,POPCNT,DEADLINE,AES,XSAVE,AVX,F16C,RDRAND>
cpu0: cpuid 6 eax=dfcff7<SENSOR,ARAT> ecx=409<EFFFREQ>
cpu0: cpuid 7.0 ebx=239c27eb<FSGSBASE,TSC_ADJUST,BMI1,AVX2,SMEP,BMI2,ERMS,INVPCID,RDSEED,ADX,SMAP,CLFLUSHOPT,CLWB,PT,SHA> ecx=98c027ac<UMIP,PKU,WAITPKG,PKS> edx=fc1cc410<MD_CLEAR,IBT,IBRS,IBPB,STIBP,L1DF,SSBD>
cpu0: cpuid a vers=5, gp=6, gpwidth=48, ff=3, ffwidth=48
cpu0: cpuid d.1 eax=f<XSAVEOPT,XSAVEC,XGETBV1,XSAVES>
cpu0: cpuid 80000001 edx=2c100800<NXE,PAGE1GB,RDTSCP,LONG> ecx=121<LAHF,ABM,3DNOWP>
cpu0: cpuid 80000007 edx=100<ITSC>
cpu0: msr 10a=1488fd6b<IBRS_ALL,SKIP_L1DFL,MDS_NO,IF_PSCHANGE,TAA_NO,MISC_PKG_CT,ENERGY_FILT,DOITM,SBDR_SSDP_N,FBSDP_NO,PSDP_NO,RRSBA,OVERCLOCK,GDS_NO,RFDS_CLEAR>
cpu0: 48KB 64b/line 12-way D-cache, 32KB 64b/line 8-way I-cache, 2MB 64b/line 16-way L2 cache, 36MB 64b/line 12-way L3 cache
cpu0: smt 0, core 0, package 0
mtrr: Pentium Pro MTRR support, 10 var ranges, 88 fixed ranges
cpu0: apic clock running at 38MHz
cpu0: mwait min=64, max=64, C-substates=0.2.0.2.0.1.0.1, IBE
cpu1 at mainbus0: apid 8 (application processor)
cpu1: Intel(R) Core(TM) i9-14900, 5489.15 MHz, 06-b7-01, patch 0000012b
cpu1: smt 0, core 4, package 0
cpu2 at mainbus0: apid 16 (application processor)
cpu2: Intel(R) Core(TM) i9-14900, 5488.76 MHz, 06-b7-01, patch 0000012b
cpu2: smt 0, core 8, package 0
cpu3 at mainbus0: apid 24 (application processor)
cpu3: Intel(R) Core(TM) i9-14900, 5488.84 MHz, 06-b7-01, patch 0000012b
cpu3: smt 0, core 12, package 0
cpu4 at mainbus0: apid 32 (application processor)
cpu4: Intel(R) Core(TM) i9-14900, 5488.65 MHz, 06-b7-01, patch 0000012b
cpu4: smt 0, core 16, package 0
cpu5 at mainbus0: apid 40 (application processor)
cpu5: Intel(R) Core(TM) i9-14900, 5488.63 MHz, 06-b7-01, patch 0000012b
cpu5: smt 0, core 20, package 0
cpu6 at mainbus0: apid 48 (application processor)
cpu6: Intel(R) Core(TM) i9-14900, 5488.74 MHz, 06-b7-01, patch 0000012b
cpu6: smt 0, core 24, package 0
cpu7 at mainbus0: apid 56 (application processor)
cpu7: Intel(R) Core(TM) i9-14900, 5488.88 MHz, 06-b7-01, patch 0000012b
cpu7: smt 0, core 28, package 0
cpu8 at mainbus0: apid 64 (application processor)
cpu8: Intel(R) Core(TM) i9-14900, 4290.12 MHz, 06-b7-01, patch 0000012b
cpu8: 32KB 64b/line 8-way D-cache, 64KB 64b/line 8-way I-cache, 4MB 64b/line 16-way L2 cache, 36MB 64b/line 12-way L3 cache
cpu8: smt 0, core 32, package 0
cpu9 at mainbus0: apid 66 (application processor)
cpu9: Intel(R) Core(TM) i9-14900, 4290.11 MHz, 06-b7-01, patch 0000012b
cpu9: smt 0, core 33, package 0
cpu10 at mainbus0: apid 68 (application processor)
cpu10: Intel(R) Core(TM) i9-14900, 4290.11 MHz, 06-b7-01, patch 0000012b
cpu10: smt 0, core 34, package 0
cpu11 at mainbus0: apid 70 (application processor)
cpu11: Intel(R) Core(TM) i9-14900, 4290.11 MHz, 06-b7-01, patch 0000012b
cpu11: smt 0, core 35, package 0
cpu12 at mainbus0: apid 72 (application processor)
cpu12: Intel(R) Core(TM) i9-14900, 4290.12 MHz, 06-b7-01, patch 0000012b
cpu12: smt 0, core 36, package 0
cpu13 at mainbus0: apid 74 (application processor)
cpu13: Intel(R) Core(TM) i9-14900, 4290.11 MHz, 06-b7-01, patch 0000012b
cpu13: smt 0, core 37, package 0
cpu14 at mainbus0: apid 76 (application processor)
cpu14: Intel(R) Core(TM) i9-14900, 4290.11 MHz, 06-b7-01, patch 0000012b
cpu14: smt 0, core 38, package 0
cpu15 at mainbus0: apid 78 (application processor)
cpu15: Intel(R) Core(TM) i9-14900, 4290.11 MHz, 06-b7-01, patch 0000012b
cpu15: smt 0, core 39, package 0
cpu16 at mainbus0: apid 80 (application processor)
cpu16: Intel(R) Core(TM) i9-14900, 4290.07 MHz, 06-b7-01, patch 0000012b
cpu16: smt 0, core 40, package 0
cpu17 at mainbus0: apid 82 (application processor)
cpu17: Intel(R) Core(TM) i9-14900, 4290.11 MHz, 06-b7-01, patch 0000012b
cpu17: smt 0, core 41, package 0
cpu18 at mainbus0: apid 84 (application processor)
cpu18: Intel(R) Core(TM) i9-14900, 4290.11 MHz, 06-b7-01, patch 0000012b
cpu18: smt 0, core 42, package 0
cpu19 at mainbus0: apid 86 (application processor)
cpu19: Intel(R) Core(TM) i9-14900, 4290.11 MHz, 06-b7-01, patch 0000012b
cpu19: smt 0, core 43, package 0
cpu20 at mainbus0: apid 88 (application processor)
cpu20: Intel(R) Core(TM) i9-14900, 4290.07 MHz, 06-b7-01, patch 0000012b
cpu20: smt 0, core 44, package 0
cpu21 at mainbus0: apid 90 (application processor)
cpu21: Intel(R) Core(TM) i9-14900, 4290.11 MHz, 06-b7-01, patch 0000012b
cpu21: smt 0, core 45, package 0
cpu22 at mainbus0: apid 92 (application processor)
cpu22: Intel(R) Core(TM) i9-14900, 4290.11 MHz, 06-b7-01, patch 0000012b
cpu22: smt 0, core 46, package 0
cpu23 at mainbus0: apid 94 (application processor)
cpu23: Intel(R) Core(TM) i9-14900, 4190.34 MHz, 06-b7-01, patch 0000012b
cpu23: smt 0, core 47, package 0
ioapic0 at mainbus0: apid 2 pa 0xfec00000, version 20, 120 pins
acpimcfg0 at acpi0
acpimcfg0: addr 0xc0000000, bus 0-255
acpiprt0 at acpi0: bus 0 (PC00)
acpiprt1 at acpi0: bus -1 (PEG1)
acpiprt2 at acpi0: bus -1 (RP09)
acpiprt3 at acpi0: bus -1 (RP10)
acpiprt4 at acpi0: bus -1 (RP11)
acpiprt5 at acpi0: bus -1 (RP12)
acpiprt6 at acpi0: bus -1 (RP13)
acpiprt7 at acpi0: bus -1 (RP14)
acpiprt8 at acpi0: bus -1 (RP15)
acpiprt9 at acpi0: bus -1 (RP16)
acpiprt10 at acpi0: bus -1 (RP01)
acpiprt11 at acpi0: bus -1 (RP02)
acpiprt12 at acpi0: bus -1 (RP03)
acpiprt13 at acpi0: bus -1 (RP04)
acpiprt14 at acpi0: bus -1 (RP05)
acpiprt15 at acpi0: bus -1 (RP06)
acpiprt16 at acpi0: bus -1 (RP07)
acpiprt17 at acpi0: bus -1 (RP08)
acpiprt18 at acpi0: bus -1 (RP17)
acpiprt19 at acpi0: bus -1 (RP18)
acpiprt20 at acpi0: bus -1 (RP19)
acpiprt21 at acpi0: bus -1 (RP20)
acpiprt22 at acpi0: bus -1 (RP21)
acpiprt23 at acpi0: bus -1 (RP22)
acpiprt24 at acpi0: bus -1 (RP23)
acpiprt25 at acpi0: bus -1 (RP24)
acpiprt26 at acpi0: bus 1 (RP25)
acpiprt27 at acpi0: bus -1 (RP26)
acpiprt28 at acpi0: bus -1 (RP27)
acpiprt29 at acpi0: bus -1 (RP28)
acpiec0 at acpi0: not present
acpipci0 at acpi0 PC00: 0x00000000 0x00000011 0x00000001
com0 at acpi0 UAR1 addr 0x3f8/0x8 irq 4: ns16550a, 16 byte fifo
com0: console
com1 at acpi0 UAR2 addr 0x2f8/0x8 irq 3: ns16550a, 16 byte fifo
"ACPI000E" at acpi0 not configured
acpibtn0 at acpi0: SLPB
acpicpu0 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu1 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu2 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu3 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu4 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu5 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu6 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu7 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu8 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu9 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu10 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu11 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu12 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu13 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu14 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu15 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu16 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu17 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu18 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu19 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu20 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu21 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu22 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
acpicpu23 at acpi0: C3(200@1048 mwait.1@0x60), C2(350@127 mwait.1@0x21), C1(1000@1 mwait.1), PSS
"PNP0C14" at acpi0 not configured
"PNP0C14" at acpi0 not configured
intelpmc0 at acpi0: PEPD
state 0: 0x7f:1:2:0x00:0x0000000000000060
counter: 0x7f:64:0:0x00:0x0000000000000632
frequency: 0
state 1: 0x7f:1:2:0x00:0x0000000000000060
counter: 0x00:32:0:0x03:0x00000000fe001098
frequency: 32768
acpibtn1 at acpi0: PWRB
tpm0 at acpi0 TPM_ 2.0 (TIS) addr 0xfed40000/0x5000, device 0x001d15d1 rev 0x36
"INTC10A0" at acpi0 not configured
"PNP0C0B" at acpi0 not configured
"PNP0C0B" at acpi0 not configured
"PNP0C0B" at acpi0 not configured
"PNP0C0B" at acpi0 not configured
"PNP0C0B" at acpi0 not configured
"PNP0C14" at acpi0 not configured
"PNP0C14" at acpi0 not configured
"PNP0C14" at acpi0 not configured
acpipwrres0 at acpi0: BTRT
acpipwrres1 at acpi0: DBTR
acpipwrres2 at acpi0: WRST
acpipwrres3 at acpi0: FN00, resource for FAN0
acpipwrres4 at acpi0: FN01, resource for FAN1
acpipwrres5 at acpi0: FN02, resource for FAN2
acpipwrres6 at acpi0: FN03, resource for FAN3
acpipwrres7 at acpi0: FN04, resource for FAN4
acpitz0 at acpi0: critical temperature is 105 degC
acpipwrres8 at acpi0: PIN_
acpivideo0 at acpi0: GFX0
acpivout0 at acpivideo0: DD1F
acpivout1 at acpivideo0: DD2F
cpu0: using VERW MDS workaround
cpu0: Enhanced SpeedStep 5488 MHz: speeds: 2001, 2000, 1900, 1800, 1700, 1600, 1500, 1400, 1300, 1200, 1100, 1000, 900, 800 MHz
pci0 at mainbus0 bus 0
0:31:5: mem address conflict 0xfe010000/0x1000
pchb0 at pci0 dev 0 function 0 "Intel Core 13G Host" rev 0x01
inteldrm0 at pci0 dev 2 function 0 "Intel Graphics" rev 0x04
drm0 at inteldrm0
inteldrm0: msi, ALDERLAKE_S, gen 12
"Intel Core 13G DTT" rev 0x01 at pci0 dev 4 function 0 not configured
xhci0 at pci0 dev 20 function 0 "Intel 600 Series xHCI" rev 0x11: msi, xHCI 1.20
usb0 at xhci0: USB revision 3.0
uhub0 at usb0 configuration 1 interface 0 "Intel xHCI root hub" rev 3.00/1.00 addr 1
"Intel 600 Series Shared SRAM" rev 0x11 at pci0 dev 20 function 2 not configured
iwx0 at pci0 dev 20 function 3 "Intel Wi-Fi 6 AX211" rev 0x11, msix
"Intel 600 Series HECI" rev 0x11 at pci0 dev 22 function 0 not configured
puc0 at pci0 dev 22 function 3 "Intel 600 Series KT" rev 0x11: ports: 16 com
com4 at puc0 port 0 apic 2 int 19: ns16550a, 16 byte fifo
ahci0 at pci0 dev 23 function 0 "Intel 600 Series AHCI" rev 0x11: msi, AHCI 1.3.1
ahci0: PHY offline on port 4
ahci0: PHY offline on port 5
ahci0: PHY offline on port 6
ahci0: PHY offline on port 7
scsibus1 at ahci0: 32 targets
ppb0 at pci0 dev 26 function 0 "Intel 600 Series PCIE" rev 0x11: msi
pci1 at ppb0 bus 1
nvme0 at pci1 dev 0 function 0 "Samsung PM9C1a NVMe" rev 0x00: msix, NVMe 2.0
nvme0: SAMSUNG MZVL81T0HDLB-00BLL, firmware 4L2QKXD7, serial S7G8NF0X420031
scsibus2 at nvme0: 2 targets, initiator 0
sd0 at scsibus2 targ 1 lun 0: <NVMe, SAMSUNG MZVL81T0, 4L2Q>
sd0: 976762MB, 512 bytes/sector, 2000409264 sectors
pcib0 at pci0 dev 31 function 0 vendor "Intel", unknown product 0x7a83 rev 0x11
azalia0 at pci0 dev 31 function 3 "Intel 600 Series HD Audio" rev 0x11: msi
azalia0: codecs: Realtek ALC897, Intel/0x2818, using Realtek ALC897
audio0 at azalia0
ichiic0 at pci0 dev 31 function 4 "Intel 600 Series SMBus" rev 0x11: apic 2 int 18
iic0 at ichiic0
iic0: addr 0x49 15=2c 16=20 19=04 1b=05 1c=60 1e=60 1f=60 20=89 21=78 22=63 25=78 26=63 27=78 28=63 29=80 2a=88 2b=42 2c=20 2d=22 2e=04 2f=5a 32=80 34=0e 3b=06 3c=0b 3d=2a words 00=0000 01=0000 02=0000 03=0000 04=0000 05=0000 06=0000 07=0000
iic0: addr 0x4b 15=2c 16=20 19=04 1b=05 1c=60 1e=60 1f=60 20=89 21=78 22=63 25=78 26=63 27=78 28=63 29=80 2a=88 2b=42 2c=20 2d=22 2e=04 2f=5a 32=80 34=0e 3b=06 3c=0b 3d=2a words 00=0000 01=0000 02=0000 03=0000 04=0000 05=0000 06=0000 07=0000
"Intel 600 Series SPI" rev 0x11 at pci0 dev 31 function 5 not configured
em0 at pci0 dev 31 function 6 "Intel I219-LM" rev 0x11: msi, address 04:7c:16:fb:15:1d
isa0 at pcib0
isadma0 at isa0
pckbc0 at isa0 port 0x60/5 irq 1 irq 12
pckbd0 at pckbc0 (kbd slot)
wskbd0 at pckbd0 mux 1
pcppi0 at isa0 port 0x61
spkr0 at pcppi0
vmm0 at mainbus0: VMX/EPT
efifb at mainbus0 not configured
ugen0 at uhub0 port 14 "Intel Bluetooth" rev 2.01/0.02 addr 2
vscsi0 at root
scsibus3 at vscsi0: 256 targets
softraid0 at root
scsibus4 at softraid0: 256 targets
root on sd0a (3fed1616e6e06415.a) swap on sd0b dump on sd0b
drm:pid0:ct_send *ERROR* [drm] *ERROR* GT0: GUC: CT: No response for request 0x4000 (fence 1)
drm:pid0:intel_guc_ct_send *ERROR* [drm] *ERROR* GT0: GUC: CT: Sending action 0x4000 failed (0xffffffffffffffc4e) status=0
drm:pid0:intel_huc_auth *ERROR* [drm] *ERROR* GT0: HuC: all workloads authentication failed 0xffffffffffffffc4e
drm:pid14050:ct_handle_response *ERROR* [drm] *ERROR* GT0: GUC: CT: Unsolicited response message: len 1, data 0xf0000000 (fence 1, last 1)
drm:pid14050:ct_handle_hxg *ERROR* [drm] *ERROR* GT0: GUC: CT: Failed to handle HXG message (0xfffffffffffffffee) 0xffff800000a79418h
drm:pid14050:ct_handle_msg *ERROR* [drm] *ERROR* GT0: GUC: CT: Failed to process CT message (0xfffffffffffffffee) 0xffff800000a79414h
inteldrm0: 1024x768, 32bpp
wsdisplay0 at inteldrm0 mux 1
pckbd_enable: command error
wsdisplay0: screen 0-5 added (std, vt100 emulation)
iwx0: hw rev 0x430, fw 77.f92b5fed.0, address 6c:f6:da:d6:63:84