Latency-test comes with LinuxCNC, you can run it with 'latency-test' from the prompt. For details, see WhatLatencyTestDoes.

Let the test run for at least 15 minutes (it has been suggested that the longer the better let it run for a day or overnight for instance) while you run glxgears or a similar application to stress the cpu. Move around windows, surf the web, copy files, play music etc.

If you have a multi-cpu machine, it is helpful to report results with the isolcpus boot parameter set appropriately (see elsewhere in this wiki).

Note that the numbers reported in this test are extremely precise but not necessarily extremely reproducible. Results may vary by 1000 ns from one invocation to another (e.g., by a few microseconds).

If you want to add information to this page or add a new page, follow some BasicSteps.

So, what do the results mean? If your "Max Jitter" number is less than about 15-20 microseconds (15000-20000 nanoseconds), the computer should give very nice results with software stepping. If the Max Jitter is more like 30-50 microseconds, you can still get good results, but your maximum step rate might be a little disappointing, especially if you use microstepping or have very fine pitch leadscrews. If the numbers are 100 uS or more (100,000 nanoseconds), then the PC is not a good candidate for software stepping. Numbers over 1 millisecond (1,000,000 nanoseconds) mean the PC is not a good candidate for LinuxCNC, regardless of whether you use software stepping or not.

What can be done about improving latency? See these pages:
FixingSMIIssues
TroubleShooting
If you are going to use software stepping, then read this:
TweakingSoftwareStepGeneration

Hardware that works

Motherboard	CPU	Other hardware comments	Max Interval (1.0 ms thread)	Max Jitter(ns) 1.0 ms thread	Max Interval (25 us thread)	Max Jitter (25 us thread)
Asus M488T-M	AMD Athlon II X4 640 3GHz	10.04LTS installed from LiveCD, onboard ATI Radeon 4250 video, 4GB RAM, C1E off in bios, 3-hour latency-test run with usual torture tests	1004378	7258	29312	4384
Asus M488T-M	AMD Athlon II X4 640 3GHz	10.04LTS installed from LiveCD, onboard ATI Radeon 4250 video, 4GB RAM, C1E off in bios, isolcpus=3, 3-hour latency-test run with usual torture tests	1001521	4401	27306	2378
Asus M5A88-M EVO	AMD Athlon II X2 250 3GHz	10.04LTS, ATI/AMD Radeon XFX HD 5450 512MB C1E off in bios, instances of "gzip -c /dev/urandom > /dev/null" to load up CPUs to 100%	1002993	4513	27267	2305
Asus M5A88-M EVO	AMD Athlon II X2 250 3GHz	10.04LTS, onboard Graphics 512MB, C1E off in bios, instances of "gzip -c /dev/urandom > /dev/null" to load up CPUs to 100%	1003210	4730	28967	4005
HP Compaq 8100 Elite CMT PC, HP 304Bh	i7-860 @ 2.80GHz	10.04LTS LiveCD, nVidia GT215(GeForce GT 240), HT enabled in BIOS, 8 CPUs shown to OS. many instances of "gzip -c /dev/urandom > /dev/null" to load up CPUs to 100%, ran test for 10-15min	991469	9885	30647	5934
Asus A7N8X	AMD Athlon-XP Barton @2.3GHz	Gentoo x86, GeForce2 MX400 nv 2x512MB	1007436	7796	33046	8055
Asus P5P41D	Intel Core2Duo E7400 2.8GHz	Ubuntu 10.01 Live CD, PNY PCI-E GeForce 7300 256mb	1010178	20111	42055	22584
Asus P5G41-M LE/CSM	Intel Core2Duo E6550 2.3GHz	Ubuntu 10.04 LTS, 2G DDR2 1066 Ram (2) 1g sticks, Mesa 5i20, onboard Intel GMA X4500 Video, Intel G41 Chipset, Disabled ACPI, everything just worked	1033641	37161	41631	16719
ABIT KT7A-RAID	AMD Athlon Thunderbird 1200+ (1.2GHz)	ATI Radeon RV100 QY (VE/7000) AGP Card. Disable RAID in BIOS. SIIG LPT2 ISA Card. 3COM Fast Etherlink XL PCI. 2x 256MB Kingston RAM (512 MB). Sinlge HDD and CD-ROM. VESA driver.	1006741	10815	40234	17746
ABIT KT7A-RAID	AMD Athlon Thunderbird 1200+ (1.2GHz)	ATI 3D Rage IIC AGP Card. Disable RAID in BIOS. SIIG LPT2 ISA Card. 3COM Fast Etherlink XL PCI. 2x 256MB Kingston RAM (512 MB). Sinlge HDD and CD-ROM. VESA driver.	1006520	10206	39454	16567
Advantech PCM-9588	Celeron @ 1.0 GHz	Intel 910GMLE Video Card, 1g RAM, Mesa 4i65, Award BIOS	1004842	8337	36363	12058
ASRock H61M-HVS	Intel Celeron G530	4GB Ram, isolcpus=1, C1E/C3/C6 suspend states disabled in BIOS, ATI Radeon 2400HD w/ "radeon" driver. Full details: http://sourceforge.net/mailarchive/forum.php?thread_name=5b3301cccd23%241a33e5e0%244e9bb1a0%24%40d-silva.org&forum_name=emc-users	992204	4364	29631	4935
ASRock P4i65G	Intel Pentium 4 @ 3.0 Ghz	using onboard video 1 GB RAM	1007169	11193	36043	11738
ASRock PV530A-ITX	VIA PV530@1.8GHz, 4GB Ram	ATI Radeon 9200 Pro (256 MB) PCI card. Networking OFF. Ubuntu 10.04. Kingston SSD. glxgears running @ 390 fps. Note: Axis choked using on-board video. Measured 33 Watts total power draw by Mini-ITX computer running LinuxCNC	1001094	5934	33281	9325
ASUS AT5NM10-I	Intel D510 1.66GHz	Ubuntu10.04LTS 2.6.32-122-rtai kernel 2GB RAM, 30GB SATA/SSD, hyperthreading disabled, PS/2 keyboard and mouse, no isolcpus parameter, test ran 15m with 2Xglxgears, web surfing, taking directory listing of external USB HD, playing movie from external HD in VLC	1005425	12225	39555	15616
ASUS AT5NM10-I	Intel D510 1.66GHz	Ubuntu10.04LTS 2.6.32-122-rtai kernel 2GB RAM, 30GB SATA/SSD, hyperthreading disabled, PS/2 keyboard and mouse, isolcpus=1 parameter, same test as above	-	6395	-	9073
ASUS AT5NM10-I	Intel D510 1.66GHz	Ubuntu10.04LTS 2.6.32-122-rtai kernel 2GB RAM, 30GB SATA/SSD, hyperthreading disabled, no keyboard and mouse, isolcpus=1 parameter, running headless with Gnome and X shut down, same test as above while logged in via ssh -Y from remote computer	996411	3211	27885	3222
ASUS M4N78-SE	AMD Athlon II X2 250 - 3.0GHz	Asus HDATI 3450 256MB graphics card	1004855	8403	38677	14372
ASUS P4P800-VM	Intel Pentium 4 - 3.0GHz	Bios A.M. 1014.006, 1GB SDRam, Intel 82865 controller on board video/network/serial/parallel/usb/AC97 sound	1006527	10196	35768	12023
ASUS P4S800D-X	2.6GHZ Pentium 4	GeForce MX4000 AGP	1005493	8988	35368	12443
ASUS P3C2000	600MHZ Pentium III	ATI Rage AGP (might be on the edge)	1029886	33381	49221	24916
ASUS P5B DELUXE	INTEL PENTIUM D915 2800Mhz	ASUS ATI RADEON EAH2400XT, 1Gb RAM	1021102	24597	55135	30830
ASUS PC-DL	Dual Xeon 3.06 (HT Off,P4 style)	Nvidia 6600GT with binary driver, on SMP kernel, Note there is a ~40k latency spike when starting openGL windows, all results are with GLX gears running, as well as xchat and firefox while installing a bunch of software	993562	6471	27011	2458
Biostar M7VIG 400, rev. 7.3	AMD Athlon XP 2600+	512mB RAM, AGP video card running "vesa" driver (STG4000 [3D Prophet Kyro Series] (rev 01))	1,006,353	9,848	39,247	15,099
Compaq Deskpro EN	1GHZ Pentium III	Onboard video - Di/sable power saving in bios - Nice machine	1011400	14895	35748	11876
Dell D600 w/SMI fix, Dapper	1.7GHz	Firefox, Ooo 3.0, Boot with wireless PCMCIA card seems to give immediate unacceptable results (>1.8ms), requires more checking - should check latency-test after boot	1010992	14770	43575	19270
Dell Dimension 2400 Intel 845GV chipset BIOS ver.A05	2.66GHz Pentium 4 512KB cache	1GB RAM - Integrated Intel 3D Extreme Graphics	1006298	9905	35597	11875
Dell Dimension 3100	3GHz P4	Intel 915G chipset, BIOS ver.A04, 512MB, Only 2 PCI slots No Built in Serial or Parallel Ports!!! Onboard video - must disable SMI	1009636	13135	41260	19167
Dell Dimension XPS T450 Intel 440BX AGPset BIOS ver.A04	450MHz Pentium III 512KB cache	384MB RAM ATI Rage 128 AGP	1020462	25170	40680	16375
Dell Dimension 4100	Intel 866 PIII	Intel 815 chipset, nVidea NV34 GeForce FX5200 AGP 128mb video(upgrade), Admtek NC100 10/100 network, 512Mb PC133 ram, legacy usb=disabled and PNP OS=YES, COM1=enabled, LPT=Bidirectional in bios	1010073	13863	37657	13352
Dell Inspiron 530S	Intel(R) Celeron(R) CPU 450 @ 2.20GHz	open glxgears two dozen times and rescaled a small image to 10000 its size	1009695	13833	38635	14386
Dell Inspiron 8500	Intel Pentium Mobile 2GHz	FixingSMIIssues	1006175	12080	36855	12735
Dell Optiplex GX270	2.8GHZ Pentium 4	Onboard video - must disable SMI	1006360	9952	35976	11689
Dell Optiplex 360	E7200 @ 2.53 GHz	Intel G31 onboard Video. SMP Kernel	1010913	16443	39908	14966
Dell Optiplex GX240	1.8GHZ Pentium 4	Ati Rage AGP must disable SMI Caveat:- later versions used the 82801BA_12 chipset which is not one of the ones causing SMI problems. Check the chipset by running lspci -vv and run latency tests before automatically trying to load the rtai_smi module	1010203	13698	38875	14714
Dell Optiplex GX150	P3 1GHz	remote access, NOT using onboard video	1004741	8236	39224	14919
Dell Optiplex 745	Intel Core2 Duo 6300 1.86GHz	3GB RAM, onboard Intel graphics, no bios adjustments or cpu isolation, 1-hour latency-test run from LiveCD?, usual torture tests	163063	63823	49578	24597
ECS KM400-M2 (V1.0)	Sempron 2200	On-board Video	1,005,717	9,460	33,956	9,930
ECS Goal3	AMD Athlon 64 3200+	Ati radeon HD 4650 pci-e video card - on board video seems to work OK for latency but has issue with on screen 'noise' at higher res/color depths	1001253	5044	29867	6203
Fujitsu-Siemens Green PC	Pentium 4 2.4 GHz	Low profile desktop with mini ATX board and Intel 82801EB/ER (ICH5/ICH5R) chipset & 82865G graphics. Running 8.04 with stock 2.6.24-16-rtai kernel, long latency test (UPDATE - CAUTION - Bought another identical computer and it produced 200000+ spikes on base thread, cause not established presently)	1003341	6836	33958	9653
Gigabyte GA-P35-S3G	E4600 Core Duo- 2.4GHz	XFX GeForce 8400GS 256mb graphics card	1002443	5982	34275	9970
Gigabyte GA-P35-S3G	E4600 Core Duo- 2.4GHz	Asus GeForce 8600GT 512mb graphics card	1006082	9577	34775	10580
Gigabyte GA-E350N mini-ITX	AMD E-350D/A45/rev3.0 Dual 1.6 GHz	3.2 GB RAM, Integrated AMD HD 6310 graphics with 384 MB, AMD Catalyst Version 10.12., Ubuntu 10.04, 2.6.32-122-rtai kernel, isolcpus=1, 1 hour test	995422	7468	29337	4869
Gigabyte GA-D525TUD mini-ITX	Atom D525 1.8Ghz	2 GB RAM, BIOS:CPU MULTI=DISABLED CPU SMARTFAN=DISABLED Azealea and other unused devices=DISABLED, noirqbalance grub mod, 2 glxgears for 2 hours	1011281	4142	15390	17561
IBM PC 300GL	PII 400 MHz 128MB RAM Ubuntu804	S3Trio 3D graphics Networking disabled	1004298	7793	32224	7995
IBM Thinkpad 600X w/ Bios version 1.11	PIII 500 MHz	320mb RAM. Runs great with Ubuntu 8.04. Lousy with 6.06.	1009205	12700	42175	17870
Intel D201GLY Mini-ITX Integrated SiS Mirage 1 graphics SiS662 Northbridge SiS964L Southbridge	Integrated Intel Celeron 215 1.33GHz CPU w/Heatsink and Fan	Shared video mem set to 128Mb Marginal for use with software step generation?	1086886	90381	66527	42222
Intel DG33BU	E6850 Core 2 Duo, 3 GHz	Asus GeForce 8200 graphics card	1004554	8879	35151	13099
Intel D945GCLF2 mini-ITX	Atom 330 2x 1.6Ghz	Specifications: http://www.intel.com/products/desktop/motherboards/D945gclf2/D945gclf2-overview.htm Note: Tested using xubuntu	1002816	6484	30998	7148
Intel D525MW mini-ITX	Atom D525 1.8Ghz	Note: Tested using ubuntu 10.04	1010065	15595	36800	11921
Intel D945GCLF2 mini-ITX	Atom 330 2x 1.6Ghz 1 GB DDR 667	Linux 2.6.30.5 + RTAI 3.7.1 with SMP support hyperthreading is disabled from BIOS 2nd core is isolated from GRUB with "isolcpus=1" Debian Lenny from LiveUSB (no harddisk) onboard video with Intel driver	996381	5101	30121	5428
Jetway J7F2WE1G	1.0Ghz Via	Via Unichrome on-board 256M ram - vesa driver via driver has opengl issues	1005013	8902	32938	9020
Jetway J7F2WE1G5D mini-ITX	VIA C7 1.5Ghz	Specifications: http://www.jetway.com.tw/jetway/system/productshow2.asp?id=379&proname=J7F2WE1G5D Note: Tested using xubuntu	1006224	10226	32840	8846
MSI K9N6PGM2-V	Athlon 64 X2 6000+ (3.1 GHz)	onboard video disabled. Used PCI-E GeForce 8600 GTS	1005933	9428	39591	15286
MSI P41-C31	E5400 Core Duo 2.7GHz	2GB Ram DDR3, vesa driver on Radeon R4350	1006443	10031	35114	11770
PCChips M810D	AMD Athlon(tm) XP 2200+	256 M RAM [SiS] 65x/M650/740 PCI/AGP VGA Display Adapter	1005209	8704	34374	10498
Soyo SV-7EVM	800Mhz PIII	Matrox MGA 2064W 8meg- Disable APM ACPI disabled - 512M ram - had to remove ASUS cdrw	1021795	28115	51935	27630
Shuttle ?model	2.0Ghz Celeron	?vid card ?shared mem ? driver ?notes - 496M ram	1011599	15588	38390	15655
VIA PT800DBP r1.0	2.6Ghz P4 512k cache	NVidia GeForce4 MX 440 AGP8X rev193 driver 'nv' 65536Kram- Disable APM ACPI disabled - 512M ram	1012219	15714	40981	19721
Via PCM7G PC2500G	VIA C7-D 1500MHz	Via Unichrome on-board 512M ram - vesa driver Some Bios changes	100832	11824	35941	11636
Vostro 200	2.2Ghz Intel Core Duo	?vid card ? driver ?notes - 1G ram	1006967	10462	36270	12266
ZOTAC GF6100-B-E	Dual Core	Onboard Vid	-	<6000	-	<6000
Dell D600	1.6GHz + ATI Mobility	2GB Ram; Ubuntu 8.04 installed from LiveCD + SMI Fix + 10*Glxgears + 1hour	1703642	707137	103020	78715
Dell D600	1.6GHz + ATI Mobility	2GB Ram; Ubuntu 8.04 installed from LiveCD + without SMI fix + 10*Glxgears -> unusable	37066563	36070058	36060747	36036442
ASRock K10N78FullHD-hSLI R3.0	Athlon 64 X2 6000+ and NVidia 9800GTX+	4GB Ram + Booted from 8.04 LiveCD + 10*Glxgears + 1hour	1005000	6811	39818	15513
GA-MA785GM-UD2H	Athlon Dual Core 4850e and onboard graphic	6GB Ram + Booted from 8.04 LiveCD + 10*Glxgears + 1hour	1005612	9141	34062	9757
eMachines ET1331-45	Athalon II X2 255 dual core - 64 bit (3.1GHz)	Asus GeoForce 210 1GB DDR3 (EN210SILENTDI3) video (proprietary driver "current") + PC 3GB DDR2 RAM + PCI parport Manhattan 158220 - 20 hr test max spike numbers 30% more than typical for all numbers. Spike coincides w/ maximizing flash video window in Firefox. Anything else keeps lower numbers. Before installing video card (using on board video), typical numbers were similar, but with spikes ~2X current max numbers.	1008590	14710	36912	13582
HP Paviliion t3000 on-board graphic (Radeon Xpress G800)	AMD2.4 GHz	Jitter increased dramatically with network use. I won't have a network connection to the machine.	1014699	17649	43168	18448
HP DC7600	P4 3Ghz	4GB RAM, On board video, Ubuntu 10.04 LTS installed from LiveCD?, HT Disabled in BIOS, 2x glxgears running, snd kernel modules disables, SMI disabled	1000587	6107	31292	6430
Intel D425KT Mini ITX	Intel Atom D425 single core 1.8GHz	2GB RAM, disabled Hyperthreading, disabled onboard audio, LinuxCNC liveCD 10.04, 4 x glxgears + firefox running for 10 hours	1010059	14915	43769	20283
ASUS E35M1-I	AMD Fusion E-350 Dual Core 1.6GHz	8GB RAM, LinuxCNC liveCD 10.04, BIOS disabled auto over clocking & C6 (aggressive sleep mode), burn in with 4 hour stress test (I'm a programmer) stress -c 16 -i 16 -m 16 -t 14400"	1001512	12009	34003	9198
ASUS 5900pro PC	Intel P4 1.8GHz dual core	4GB RAM, Ubuntu 10.04 LTS, EIST off, C1E off, Spread Spectrum off, Disable Audio and network support, On-board video, Running GLXGEARS and reading PDFs	1001347	5347	29795	5001
Motherboard	CPU	Other hardware comments	Max Interval (1.0 ms thread)	Max Jitter(ns) 1.0 ms thread	Max Interval (25 us thread)	Max Jitter (25 us thread)

Hardware that does not work

Motherboard	CPU	Other hardware comments	Max Interval (1.0 ms thread)	Max Jitter(ns) 1.0 ms thread	Max Interval (25 us thread)	Max Jitter (25 us thread)
Intel D102GGC2	Celeron 2.4 GHz	Asus GeForce 8200 graphics card	155ms delays every 10 minutes	-	-	-
Tyan S1832D	single PIII Coppermine 700Mhz	Intel 440 AGPset AMIBIOS AF29 1G ram NVidia FX5200 AGP vesa driver	eventual Unexpected RTDelay despite good looking 8 hr test	-	-	-
Tyan S1832D	dual PIII Coppermine 700Mhz	Intel 440 AGPset AMIBIOS AF29 1G ram NVidia FX5200 AGP vesa driver	eventual Unexpected RTDelay despite good looking 8 hr test	-	-	-
Dell Optiplex 740	AMD Athlon 64 X2 Dual	-	Very big max jitter results (>7000000ns). Also problem with keyboard and mouse lockups which I will not investigate further, due to the first problem.	-	-	-
Gigabyte GA-H61MA-D3V	Intel G620	-	Intel Sandy Bridge architectures apparently don't work with RTAI patched kernels	-	-	-
Biostar A68I-E350 Deluxe	AMD APU 350D Dual-Core	4GB RAM, USB keyboard/mouse, VGA output. Factory settings in BIOS.	Very attractive board in price and features BUT within two minutes max jitters were already in the 50000ns range. No improvement running headless. Perhaps some enterprising person can figure out a BIOS setting that will make this board acceptable but for now the competing Gigabyte E350N boards are better choices.	-	-	-
next	entry	here	and here	-	-	-

Latency-Test

Hardware that works

Hardware that does not work