The Raspberry Pi Compute Module 4 Review

six years ago the raspberry pi foundation introduced the compute module a teensy tiny version of the popular raspberry pi board between then and now there have been multiple revisions to the compute module like the three plus that i have in my hand but they've all had the same basic form factor in a very limited feature set but today that all changes with this the fourth generation of the compute module the compute module 4 is basically a raspberry pi 4 model b with all the ports cut off wait wait a second no no no i i didn't tell you to actually cut the pie for just hold the saw like you're gonna cut it that's the last time i asked you to help me with one of these videos sorry about that instead of the ports you plug the compute module into another board with its special board to board connectors but the compute module has a few other tricks up its sleeve it has the option of onboard emmc storage so you can ditch slow micro sd cards it drops the usb 3 ports from the pi4 for a pci express interface meaning you can do some pretty cool things in place of those ports and it also has an external antenna connector for its wireless interface what's that oh yes now there's a version of the compute module with built-in bluetooth and wi-fi in addition to onboard gigabit wired ethernet and that leads me to the other huge difference from older generations there are now 32 different compute module flavors you can choose from whether you want onboard wi-fi or not whether you want emmc or not or whether you want one two four or even eight gigabytes of ram on this tiny thing just like the pi4 you can find all the details on the raspberry pi website but here are the highlights the cheapest cm4 is the light version with one gig of ram and no on-board storage and that runs 25 bucks the most expensive creme de la creme version with wi-fi bluetooth 8 gigs ram and 32 gigs of fast emmc storage costs 90 bucks but to use it you'll either need to build your own board to integrate it or you can buy the pi foundation's new compute module 4 i o board which is an extra 35 bucks this board turns your compute module 4 into a pi 4 on steroids because it has all the ports on a standard model b pi and then some the only thing lacking is the built-in usb 3 ports and that's a difference that might make you do a double take i remember earlier this year even upton mentioned in a podcast that the raspberry pi would someday have its pcie 1x interface exposed directly the raspberry pi 4 compute module the cm4 we will do will support nvme and now it is you get this nice pcie port on the i o board and you can plug in any pcie device as long as it only uses one lane of capacity for example if you just want to have a couple usb 3 ports like you would on a model b you can still do that using something like a seba usb pci express card that i have or if you want to get bleeding edge performance out of disk storage you can pop in an nvme adapter with an nvme drive and enjoy the fastest disk io ever at least on a raspberry pi this was technically possible with the pi4b but it required you to desolder the usb chip and wire up some teeny tiny jumpers and hack it in having a standard pci slot built in makes it easy to use whatever accessory you need i'll do a whole separate live stream later today with more discussion about pcie and the compute module 4 so be sure to subscribe to my channel to see that now before i get into performance i want to talk a little bit about why the compute module is a complete redesign from past versions a few of the things i noted in my touring pi cluster review video included the lack of enough power and onboard space to fit in all the features the pi 4 crams into its small package especially the unthrottled 1.5 gigahertz clock of the pi4 system on a chip also because of the physical constraints of the dim form factor it wouldn't have been possible at least as far as i can tell to include all the features like wi-fi with a built-in antenna emmc storage and an ethernet controller chip for all these reasons and to make it easier to affix the compute module to different boards a more specialized board to board connector was used there are two of them and they each have a hundred pins and they connect power i o and the gpio pins to the compute module one of the biggest changes from the cm3 plus and earlier is the cm4 now includes an onboard gigabit ethernet controller so you can get fast networking without paying for an extra chip on an external i o board or using an external usb adapter the headline feature though for me is the pcie slot but to be clear this is the smallest pcie flavor with just one lane or one x of bandwidth available so not to burst your bubble but you won't be able to use an nvidia rtx 3080 on your raspberry pi it still won't run crysis with 8k resolution at 240 frames per second but it will run a lot of things for starters if you're in love with usb 3 and you're sad to see it missing here you can buy a usb 3 expansion card but be sure it uses the vli vl805 chipset otherwise it might not be compatible with the raspberry pi and you'll get stuck with usb 2 speeds i actually bought three different usb cards to see how they worked and two of the three didn't provide the full usb 3 throughput for most of my devices they kept mounting drives at usb 2 speeds which was really annoying this generic pci experse card and no i didn't misspeak that's how it's actually spelled on the box it has the vl805 chip in it but it only mounted a couple of my usb 3 drives at that rate the other is like the fastest one i tested on a pi 4 mounted as usb 2 and worked fine but could only move data at really slow speeds i had higher hopes for this in a tech card but i was a little nervous about the fresco logic chip on it as it turns out it didn't mount anything at all with usb 3 speeds the best usb 3 card i tested was from seba or cyber you can try correcting a pronunciation in the comments and it even includes a usbc port it mounted all my devices at usb 3 speeds and worked perfectly with raspberry pi os just be careful plugging in power hungry devices like a usb powered spinning hard drive because it can only put through a little power since it shares the same 12v power supply with the i o board itself the thing i was most excited about though was nvme support i had to find out if an nvme drive attached directly to the raspberry pi's bus would run faster than one connected through a usb 3 port so i plugged in my xpg sx6000 drive into an adapter and nothing so i bought two other nvme to pci adapters thinking maybe mine was broken and still nothing i should note here that nvme support isn't enabled out of the box on raspberry pi os you have to run the command mod probe nvme-core and then reboot to enable the nvme kernel module anyways i could use the command lspci and see that the nvme controller from realtek was at least recognized but the drive itself never showed up when i ran lsblk and i found some weird errors in the system's logs using d message so because of the generosity of all of you who've donated to my github or patreon there are links below if you want to start supporting me today i was able to buy another spare nvme for testing i bought this samsung 970 evo plus which is a bit more expensive than the xpg drive but not too bad i popped it in the adapter and booted the pie and it worked i was able to see the device using lsblk so i formatted it and then i mounted it for testing and let me tell you it is fast you're hearing it here first the raspberry pi compute module 4 offers the fastest disk io of any raspberry pi yet and here's a graph to prove it this graph shows the four options for storage on the compute module 4. emmc microsd nvme over usb 3 say that five times fast and native nvme you can see the ability to use usb 3 or nvme drives destroys the performance of onboard emmc or microsd cards ssds are incredibly fast for sequential writes for large files but what really sets this pie apart is the ability to get native nvme performance which more than doubles random 4k performance over usb 3 drive check out that 4k write speed sadly you can't use an nvme drive as a boot volume at least not yet i think it'd be awesome if i could use a few light cm4s with an nvme drive in a tiny cluster that would absolutely knock the socks off the turing pi cluster i built earlier this year speaking of which i heard from turing machines that they do plan on building a new version 2 board with full support for the compute module 4 and i can't wait to see how it turns out alright so you can get usb or nvme over the pci bus but what about upgraded video cards well there are some slower pci video cards that work with just a 1x bus but most of them either have no drivers for linux at all or if they do have linux drivers the drivers are only available for x86 the pi uses an arm processor which wouldn't work with the x86 drivers anyways in all my searching i could only find one pci video card that would be hardware compatible with the compute module 4. but note that i said hardware compatible the graphics chip has linux drivers but only for x86 there might be a way to get it running but i'm not too optimistic but what do you think leave a comment below if you want me to try to buy one of these cards and do another video testing it out on the raspberry pi so video cards are out for now but there are a number of other adapters you can get for pci including sata adapters for hard drives and ssds sound cards network adapters and even old parallel port adapters the most important thing to look at is whether the card has linux support some things are supported out of the box but for other things you need to install a driver and it has to be compatible with not only linux but also arm processors the other headline feature compared to the older compute modules is the inclusion of onboard wi-fi and gigabit ethernet you can choose whether to get wi-fi and bluetooth but all versions even the light ones come with gigabit ethernet in courtesy of this little tiny broadcom chip the cm4 performs just as well as a pi 4 model b in my testing the wired network got 942 megabits which is about as fast as i've seen on my home gigabit network and it's infinitely faster than the lack of a wired network chip on the older compute module boards even with the turing pi cluster board it only gave you 100 megabits per compute module so this feature alone is a huge improvement in wireless which is also not available at all on older compute modules gets up to 80 megabits on my home network now here's where it gets a little more interesting the cm4 is also the first pi of any type to offer a ufl antenna connector since a lot of companies will integrate the cm4 into an industrial device with a metal enclosure if they want wi-fi to work at all they need an external antenna the pi foundation will actually sell you a compatible and certified antenna you can plug into this teeny tiny connector and that antenna can then be mounted somewhere to allow the pi to still get a really good wi-fi connection technically though and you didn't hear this from me you could grab any standard ufl antenna like the one i have here and use it i did some testing with this antenna just to compare the tiny built-in triangular antenna on the pcb and the results kind of surprised me with the built-in pcb antenna which i didn't expect to perform amazing the signal level was negative 43 dbm with a quality rating of 67 out of 70 and that's pretty respectable even though my router is only about 20 feet away with the external antenna i could get it down to negative 40 dbm with a quality rating of 70 out of 70 but that was only after i adjusted its position a bit to get the best possible signal if i unplugged the antenna though the signal was terrible at negative 74 dbm with a quality of 36 out of 70 and it only did about 6 megabits so the onboard antenna is a great design as long as you're not enclosing the pi in a metal box or a faraday cage and one quick note on the external antenna it's actually disabled by default and to enable it and turn off the pcb antenna you have to edit the boot config.txt file on the pi and add the line dt param equals ant2 then reboot your compute module so for both wireless and wired networking the cm4 is on par with the regular pi 4 and far beyond the capability of older compute modules now if you've used the pi 4 you know what kind of cpu performance you'll get with the cm4 but if you use the compute module 3 plus or an older version the compute module 4 is a huge leap in performance for a few different reasons first the cpu clock was increased from an underclocked 1.2 gigahertz on the cm3 plus to 1.5 gigahertz on the cm4 second the cpu itself was upgraded from a cortex a53 to a72 and that means there's more bandwidth more caches and all around better performance even at the same clock speeds but don't take my word for it here are some benchmarks i ran using pharonics that show the difference these three benchmarks represent some real world scenarios that require good cpu performance to run well in every case the compute module 4 is twice as fast as the previous 3 plus it's barely even a contest in real world use for things like web browsing and playing games the difference isn't usually quite as stark but it does feel a lot faster and every time i go back to my 3 plus i remember how big the performance gap is so better cpu better networking what about emmc for storage crazy people like me spend a lot of time trying all kinds of hacky solutions to get the most disk performance possible but for most people i think the built-in emmc is gonna offer the best performance for the dollar the pi engineers increased the emmc bus from 4 bits to 8 bits so you can get more bandwidth out of the same emmc storage and it really shows in the benchmarks i ran random i o is twice as fast on the cm4 than it was on the cm3 and sequential performance is way better too the compute modules 3's emmc was a bit slower than the fastest micro sd cards i tested but the cm4 is neck and neck meaning there are no compromises compared to microsd and since random i o is more important for general computing that makes the built-in emmc the best option for most people especially since it keeps the whole compute module package really tiny so it'll fit almost anywhere now if you need to flash a new os to the emmc it's actually a slight bit more complicated than doing the same thing with microsds but thanks to raspberry pi's usb boot utility it's not too hard as long as you have another computer or pi handy i'll cover how to do that in a later video speaking of usb boot what about booting the compute module from usb drive after all i did a whole video on how to do it with the pi 4. can you also do it with the compute module 4 well yes but if you want usb 3 speeds you'll need to drop a usb pci adapter card in the single pci express slot and plug in your drive through that the ports on the pi itself on the i o board are usb 2 only but it works just as well as on the pi 4 assuming you have a usb 3 adapter i was really hoping to be able to boot the pi off and nvme and do some more testing that way but as i mentioned earlier that's not officially supported yet i even tried doing it with a light compute module but the pi just sits there looking for microsd then usb then microsd then usb and it keeps doing that forever technically you could still boot off an nvme if you put it in a usb 3 adapter and plug that into a pci adapter but that's not the same thing as booting directly off an nvme drive and you miss out on a bit of performance one other thing i wanted to check out though is how well the compute module performs as a nas or network attached storage using nfs i currently have an old mac mini a 2011 that i still use to store many terabytes of old video files and backups of my computers but it's so old it's not even supported by apple anymore so i wanted to see if the compute module could be faster than the 10 year old mac mini i use for file storage and spoiler alert it is on the mac mini the fastest consistent write speed i could get is around 35 megabytes per second mostly because the tribes are all attached to the old usb 2 ports on the pi if i write to either an external usb drive or an nvme drive i could write over the network at about 70 megabytes per second which is double the speed of my old mac mini now a brand new mac mini would saturate the network's bandwidth and give me somewhere around 100 megabytes per second but that would also cost at least 800 bucks and that's a lot to pay to get those extra 30 megabytes and i'm sure there are a few of you watching this video wondering why i jeff gearling don't have a 10 gig fiber home network with a sand for my storage and i'd kindly ask you to direct your questions to my wife who i just can't convince that a san is more essential for our family than things like food or toilet paper alright so enough of the compute module itself it is to put it in the words of steve jobs a screamer compared to all the previous pies what about its official companion development board the i o board has a few tricks up its sleeve too not only does it have all the same breakouts and connections that the old i o board had it also has poe support included standard so you can power and network the pi over just one ethernet cable we've already covered the pcie slot but right above it is a 4-pin psu connector that can be used to provide power to accessories as well as a 4-pin fan connector that can power and control a fan down along the bottom there's a 12-volt barrel plug power jack in the description i actually have a link to the power adapter i'm using with the i o board along with links to all the other accessories that i've mentioned throughout this video then there's a micro sd card slot for use with the compute module lite version two usb 2 ports along with a header for two more usb ports and the network jack it also has two full-size hdmi ports so you can drive up to two external displays just like the regular pi 4. it's interesting that they're full size because now when i'm switching between all my different pi projects i have full size hdmi on the original pi pi 2 pi 3 pi 3 plus pi a plus then i have mini hdmi on the pi zero and finally micro hdmi on the pi 4. so now we're back full circle to full size hdmi on the i o board go figure there's a built-in rtc or real-time clock with a slot for a standard backup battery and there's a standard hat connector and that stands for hardware attached on top and it allows you to interface with the pi's gpio it has mounting holes in the same place as a standard pi b model so you can mount hats on the board directly and finally there are some display and camera connectors along the side and top edge along with a set of jumpers to help when doing things like flashing an emmc module or to disable firmware updates or to boot the pi if it's shut down there are two things i think i could call it as downsides to the i o board and the compute module board to board designs first the i o board is pretty large i understand why since it tries to support every feature of the cm4 including mounting full-size pie hats but it'd be nice if it took up a little bit less space even if it drops a few features second having two 100 pin board to board connectors close together makes attaching and removing the compute module a slight bit more tricky than i think it should be you're supposed to pull straight up to detach the module but it's pretty much impossible to do that unless you use spudgers with your fingers you kind of have to pry up one side first and the module kind of jumps off the board plugging it in is a little bit easier since you can just push down with equal pressure on both sides there are a ton of other little details that i can't cover in this video but i think the pi foundation did a great job with this board given the constraints of the form factor and the price i'm really happy with how the compute module 4 turned out and like i said earlier in this video i talked to turing machines and they said they're already hard at work on a version 2 of their turing pi cluster board the one that i reviewed in my pi cluster series earlier this year once that board comes out i'm going to do everything i can to get one load it up with compute models and rebuild my pi drama cluster on it and i'll be sure to make some videos of that process the compute module 4 offers all the performance of the pi 4 model b and it blows away the compute module 3 plus and all the other versions that came before the new form factor means the compute module 4 is faster takes up less board space and provides useful new features like onboard wireless and wired networking and an external pcie slot check it out and see where you can buy one on raspberrypi.org subscribe and support me on github or patreon if you liked this video until next time i'm jeff gearling but they've all had the very same base the very what i don't even i didn't write that you probably won't be able to use an envy and last time i said nvidia everybody made fun of me so i'm gonna get nvidia right i can't pronounce pronunciation apparently through a usb 3 slot slot who wrote this i bought this samsung 970 evo plus which i forgot to show you here it is performs as a nas or a network attack storage attacked who's attacking my network full circle to full size hdmi on the io man that was so close there's only one more line there

Channel: Jeff Geerling

Views: 266,620

Rating: 4.9345775 out of 5

Keywords: raspberry pi, compute module, compute module 4, pi cluster, cluster, cm4, sbc, single board computer, computer, industrial, performance, review, test, pi 4, pi 3 B+, pi 3+, cm3, raspbian, raspberry pi os, nvme, nvm, emmc, m.2, ssd, usb 3.0, usb, superspeed, pci, pcie, 1x, io board, version 4

Id: HUamq0ey8_M

Length: 21min 33sec (1293 seconds)

Published: Mon Oct 19 2020

Reddit Comments

[u/theoldwizard1]

The folks at Raspberry Pi have just "kicked it up" another notch ! I don't know how other SBC will be able to keep up !!

First, adding (optional) eMMC will stop all of the complaining about boot from an SD card.

Second, the IO expansion board is GENIUS ! Hopefully the Raspberry Pi foundation will release the drawings of this board because I I think true embedded system builder will want to customize this for their applications, adding/subtracting to what is there !

You can bet, RPi5 will have more PCIe ports ! The big problem will be where to mount a PCIe connector and maintain the external footprint. Will RPi5 have eMMC standard ? Will it have SD HS-II or SDe ? Who knows !!

[u/mnewberg]

Since AMD Navi drivers in the in the Linux source code, could you add a AMD card to the raspberry pi to make an open source version of the Jetson platform?

[u/mrjbacon]

I just want to know if you can install an OS img on an M.2 SSD and boot a RPi CM4 from that, can anyone enlighten me? I've been googling different things since the announcement and I can't even find theoretical speculation regarding the topic...

Edit: nvm, found it in the video