Lenovo ThinkPad T440s : just a couple years old. Triple-booting Arch Linux and Windows too, it's plenty fast to watch even huge HD 1080p movies.
But on a new stock OpenBSD (dmesg below) it does that stuttering thing with all video, even the tiniest little YouTube or low-resolution mp4 file, even if only 3 seconds long: "ev.. er...y th... ing... stut... ters... a... few... times... per... sec... ond...", whether using mplayer or browser or any other method I've tried. I saw http://www.openbsd.org/faq/faq13.html#audioserver and tried the `rcctl set sndiod flags -b2400` advice with various frames values, huge and small, but it had no effect. Any pointers for what you'd look at, if it were you, to troubleshoot this? I'm happy to do the work, but sorry I don't know where to start. Thank you. === OpenBSD 5.9 (GENERIC.MP) #4: Thu May 19 08:22:39 CEST 2016 jas...@stable-59-amd64.mtier.org: /binpatchng/work-binpatch59-amd64/src/sys/arch/amd64/compile/GENERIC.MP real mem = 8246124544 (7864MB) avail mem = 7992012800 (7621MB) mpath0 at root scsibus0 at mpath0: 256 targets mainbus0 at root bios0 at mainbus0: SMBIOS rev. 2.7 @ 0xdcd3d000 (61 entries) bios0: vendor LENOVO version "GJET67WW (2.17 )" date 12/10/2013 bios0: LENOVO 20AQCTO1WW acpi0 at bios0: rev 2 acpi0: sleep states S0 S3 S4 S5 acpi0: tables DSDT FACP SLIC DBGP ECDT HPET APIC MCFG SSDT SSDT SSDT SSDT SSDT SSDT SSDT SSDT PCCT SSDT UEFI POAT ASF! BATB FPDT UEFI SSDT DMAR acpi0: wakeup devices LID_(S4) SLPB(S3) IGBE(S4) EXP2(S4) XHCI(S3) EHC1(S3) acpitimer0 at acpi0: 3579545 Hz, 24 bits acpiec0 at acpi0 acpihpet0 at acpi0: 14318179 Hz acpimadt0 at acpi0 addr 0xfee00000: PC-AT compat cpu0 at mainbus0: apid 0 (boot processor) cpu0: Intel(R) Core(TM) i7-4600U CPU @ 2.10GHz, 1995.69 MHz cpu0: FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUS H,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX ,SMX,EST,TM2,SSSE3,FMA3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,x2APIC,MOVBE,POPCNT ,DEADLINE,AES,XSAVE,AVX,F16C,RDRAND,PAGE1GB,LONG,LAHF,ABM,PERF,ITSC,FSGSBASE, BMI1,HLE,AVX2,SMEP,BMI2,ERMS,INVPCID,RTM,SENSOR,ARAT cpu0: 256KB 64b/line 8-way L2 cache cpu0: smt 0, core 0, package 0 mtrr: Pentium Pro MTRR support, 10 var ranges, 88 fixed ranges cpu0: apic clock running at 99MHz cpu0: mwait min=64, max=64, C-substates=0.2.1.2.4.1.1.1, IBE cpu1 at mainbus0: apid 1 (application processor) cpu1: Intel(R) Core(TM) i7-4600U CPU @ 2.10GHz, 1995.38 MHz cpu1: FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUS H,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX ,SMX,EST,TM2,SSSE3,FMA3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,x2APIC,MOVBE,POPCNT ,DEADLINE,AES,XSAVE,AVX,F16C,RDRAND,PAGE1GB,LONG,LAHF,ABM,PERF,ITSC,FSGSBASE, BMI1,HLE,AVX2,SMEP,BMI2,ERMS,INVPCID,RTM,SENSOR,ARAT cpu1: 256KB 64b/line 8-way L2 cache cpu1: smt 1, core 0, package 0 cpu2 at mainbus0: apid 2 (application processor) cpu2: Intel(R) Core(TM) i7-4600U CPU @ 2.10GHz, 1995.38 MHz cpu2: FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUS H,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX ,SMX,EST,TM2,SSSE3,FMA3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,x2APIC,MOVBE,POPCNT ,DEADLINE,AES,XSAVE,AVX,F16C,RDRAND,PAGE1GB,LONG,LAHF,ABM,PERF,ITSC,FSGSBASE, BMI1,HLE,AVX2,SMEP,BMI2,ERMS,INVPCID,RTM,SENSOR,ARAT cpu2: 256KB 64b/line 8-way L2 cache cpu2: smt 0, core 1, package 0 cpu3 at mainbus0: apid 3 (application processor) cpu3: Intel(R) Core(TM) i7-4600U CPU @ 2.10GHz, 1995.38 MHz cpu3: FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUS H,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX ,SMX,EST,TM2,SSSE3,FMA3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,x2APIC,MOVBE,POPCNT ,DEADLINE,AES,XSAVE,AVX,F16C,RDRAND,PAGE1GB,LONG,LAHF,ABM,PERF,ITSC,FSGSBASE, BMI1,HLE,AVX2,SMEP,BMI2,ERMS,INVPCID,RTM,SENSOR,ARAT cpu3: 256KB 64b/line 8-way L2 cache cpu3: smt 1, core 1, package 0 ioapic0 at mainbus0: apid 2 pa 0xfec00000, version 20, 40 pins acpimcfg0 at acpi0 addr 0xf8000000, bus 0-63 acpiprt0 at acpi0: bus 0 (PCI0) acpiprt1 at acpi0: bus -1 (PEG_) acpiprt2 at acpi0: bus 2 (EXP1) acpiprt3 at acpi0: bus 3 (EXP2) acpiprt4 at acpi0: bus -1 (EXP3) acpicpu0 at acpi0: C3(200@506 mwait.1@0x60), C2(200@148 mwait.1@0x33), C1(1000@1 mwait.1), PSS acpicpu1 at acpi0: C3(200@506 mwait.1@0x60), C2(200@148 mwait.1@0x33), C1(1000@1 mwait.1), PSS acpicpu2 at acpi0: C3(200@506 mwait.1@0x60), C2(200@148 mwait.1@0x33), C1(1000@1 mwait.1), PSS acpicpu3 at acpi0: C3(200@506 mwait.1@0x60), C2(200@148 mwait.1@0x33), C1(1000@1 mwait.1), PSS acpipwrres0 at acpi0: PUBS, resource for XHCI, EHC1 acpipwrres1 at acpi0: NVP3, resource for PEG_ acpipwrres2 at acpi0: NVP2, resource for PEG_ acpitz0 at acpi0: critical temperature is 200 degC acpibtn0 at acpi0: LID_ acpibtn1 at acpi0: SLPB acpibat0 at acpi0: BAT0 model "45N1773" serial 32828 type LION oem "SANYO" acpibat1 at acpi0: BAT1 model "45N1737" serial 26275 type LION oem "SANYO" acpiac0 at acpi0: AC unit online acpithinkpad0 at acpi0 cpu0: Enhanced SpeedStep 1995 MHz: speeds: 2701, 2700, 2600, 2400, 2300, 2100, 2000, 1800, 1700, 1600, 1400, 1300, 1100, 1000, 800, 756 MHz pci0 at mainbus0 bus 0 pchb0 at pci0 dev 0 function 0 "Intel Core 4G Host" rev 0x0b inteldrm0 at pci0 dev 2 function 0 "Intel HD Graphics" rev 0x0b drm0 at inteldrm0 inteldrm0: msi inteldrm0: 1920x1080 wsdisplay0 at inteldrm0 mux 1: console (std, vt100 emulation) wsdisplay0: screen 1-5 added (std, vt100 emulation) azalia0 at pci0 dev 3 function 0 "Intel Core 4G HD Audio" rev 0x0b: msi xhci0 at pci0 dev 20 function 0 "Intel 8 Series xHCI" rev 0x04: msi usb0 at xhci0: USB revision 3.0 uhub0 at usb0 "Intel xHCI root hub" rev 3.00/1.00 addr 1 "Intel 8 Series MEI" rev 0x04 at pci0 dev 22 function 0 not configured puc0 at pci0 dev 22 function 3 "Intel 8 Series KT" rev 0x04: ports: 1 com com4 at puc0 port 0 apic 2 int 17: ns16550a, 16 byte fifo com4: probed fifo depth: 0 bytes em0 at pci0 dev 25 function 0 "Intel I218-LM" rev 0x04: msi, address 28:d2:44:52:c6:ca azalia1 at pci0 dev 27 function 0 "Intel 8 Series HD Audio" rev 0x04: msi azalia1: codecs: Realtek ALC292 audio0 at azalia1 ppb0 at pci0 dev 28 function 0 "Intel 8 Series PCIE" rev 0xe4: msi pci1 at ppb0 bus 2 rtsx0 at pci1 dev 0 function 0 "Realtek RTS5227 Card Reader" rev 0x01: msi sdmmc0 at rtsx0 ppb1 at pci0 dev 28 function 1 "Intel 8 Series PCIE" rev 0xe4: msi pci2 at ppb1 bus 3 iwm0 at pci2 dev 0 function 0 "Intel Dual Band Wireless AC 7260" rev 0x83, msi ehci0 at pci0 dev 29 function 0 "Intel 8 Series USB" rev 0x04: apic 2 int 23 usb1 at ehci0: USB revision 2.0 uhub1 at usb1 "Intel EHCI root hub" rev 2.00/1.00 addr 1 pcib0 at pci0 dev 31 function 0 "Intel 8 Series LPC" rev 0x04 ahci0 at pci0 dev 31 function 2 "Intel 8 Series AHCI" rev 0x04: msi, AHCI 1.3 ahci0: port 0: 6.0Gb/s ahci0: port 1: 6.0Gb/s ahci0: port 2: 6.0Gb/s scsibus1 at ahci0: 32 targets sd0 at scsibus1 targ 0 lun 0: <ATA, HGST HTS725050A7, GH2Z> SCSI3 0/direct fixed naa.5000cca77ecc4724 sd0: 476940MB, 512 bytes/sector, 976773168 sectors sd1 at scsibus1 targ 1 lun 0: <ATA, ADATA SP600NS34, 5.8> SCSI3 0/direct fixed naa.5000000000000000 sd1: 122104MB, 512 bytes/sector, 250069680 sectors, thin sd2 at scsibus1 targ 2 lun 0: <ATA, SanDisk SSD U110, U21A> SCSI3 0/direct fixed naa.5001b44a6653307f sd2: 15272MB, 512 bytes/sector, 31277232 sectors, thin ichiic0 at pci0 dev 31 function 3 "Intel 8 Series SMBus" rev 0x04: apic 2 int 18 iic0 at ichiic0 spdmem0 at iic0 addr 0x50: 4GB DDR3 SDRAM PC3-12800 SO-DIMM isa0 at pcib0 isadma0 at isa0 pckbc0 at isa0 port 0x60/5 irq 1 irq 12 pckbd0 at pckbc0 (kbd slot) wskbd0 at pckbd0: console keyboard, using wsdisplay0 pms0 at pckbc0 (aux slot) wsmouse0 at pms0 mux 0 wsmouse1 at pms0 mux 0 pms0: Synaptics clickpad, firmware 8.1 pcppi0 at isa0 port 0x61 spkr0 at pcppi0 error: [drm:pid0:intel_uncore_check_errors] *ERROR* Unclaimed register before interrupt uhub2 at uhub1 port 1 "Intel Rate Matching Hub" rev 2.00/0.04 addr 2 vscsi0 at root scsibus2 at vscsi0: 256 targets softraid0 at root scsibus3 at softraid0: 256 targets root on sd1a (7d72b85cd402347e.a) swap on sd1b dump on sd1b iwm0: hw rev 0x140, fw ver 25.228 (API ver 9), address 5c:51:4f:a1:16:d9 sd3 at scsibus3 targ 1 lun 0: <OPENBSD, SR CRYPTO, 005> SCSI2 0/direct fixed sd3: 4345MB, 512 bytes/sector, 8899482 sectors