How does Windows utilize Hyperthreaded cores? - The Workshop
Linus Tech Tips
·Linus Tech Tips
·2016-05-06
·
1,453 words · ~7 min read
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hyperthreading is a feature that's been on high-end Intel CPUs for a long time
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but has often been misunderstood by the community almost as a whole today we're
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going to check out how actually it works on a Windows level how applications are
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interacting with it and what happens when you put load on actual
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threads the master case 5 by Cooler Master gives you the freedom to truly
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make your midtower PC case your own with a variety of modular parts and
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accessories check out the link in the video description to learn more many
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people are vaguely aware that hyperthreading improves performance of certain applications by making one CPU
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core behave as two so it can split the workload up more effectively but how
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does it work exactly many people seem to assume that there's a difference between
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real cores and hyperthreaded cores I mean it makes sense right once you get
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into your system Windows is going to see eight if you have eight hyperthreaded
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cores and then some of them will probably be weaker than others is that
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really how it works I mean Intel's own specs can be a bit confusing core i7s
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usually have four and then in Brackets eight listed as their number of cores
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does that mean that there are four subordinate cores or something are are
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are are the four extra cores weaker to start answering things instead of just
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repeatedly asking questions for the entire video open up toce manager on any
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system that has an i7 in it or a hyperthreaded CPU you'll see that all of
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the cores in the current case of this system the
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4790k it displays eight CPUs all of
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which show as the same thing that's because there is eight logical cores in
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the system when you read Intel spec sheet the four is for physical cores the
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eight is for what those physical cores result in which is eight logical cores
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that doesn't mean you have 12 cores that doesn't mean you have eight cores
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physically that means you have four cores physically physically and eight
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cores logically different things they don't add together very different things
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so how did these cores actually behave to find out we use unraid to set up two
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Windows Virtual machines we signed each VM four logical cores out of eight total
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then we ran some benchmarks to see if Windows actually cares whe which logical
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core it's using and to see if there's any preference between them if one of
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them is actually better than the other one some people on Forum seem to be
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under the impression that half of them like 0 1 2 and three in terms of cores
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are real cores and half of them four five six and seven are just the the
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extra hyperthreads so we're going to see how that works results showed virtually
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no difference cin bench got between 62
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and 625 per VM when we ran them
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separately when we ran them both at the same time they both got exactly
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383 so it looks like there's a bit of a performance hit even though the VM
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completely Ely separates its logical cores but at the end of the day the
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performance was the same similar story on City skylines which is a fairly CPU
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bound game both got 48 FPS when running
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separately with the performance dropping to 35 and 31 we ran them at the same
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time so there was the difference but not a huge one and due to City skylines not
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being our most consistent Benchmark it might come down to just slightly
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differences within the game we looked at it much more deeply with s zip running
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it simultaneously on both VMS gave nearly identical results between 11k and
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12K mips but when we ran it on just one it jumped to 17K to or 18K mips starting
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one first and then starting the other one a while later while it was running
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allowed us to see this balancing in real
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time it was interesting to watch as the processes were running the one you
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started first would be running faster at the beginning but over time they would
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start to equal out and it didn't actually take that long these results
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seem to make sense as hyperthreading works by sending threads to whatever the
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physical core actually has free to process instructions it doesn't split
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the physical cores into two things and leave the other half unutilized so if
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you have just one thing running it will perform better than if you have two
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running what's actually happening is that Windows can schedule two different
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threads on one physical core at the same time if the physical core is working on
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the first task but still has some resources free it can go ahead and use
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its remaining resources to process the
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second task so you won't always have a
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clean doubling or halfing of performance if you're running One Thing versus two
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but you will see substantial performance differences if you're leveraging the
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hyperthreading feature on a physical core but there is no real distinction to
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draw between The Logical cores on a hyperthreading CPU they're all the same
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thing both physically and how a hyper threading aware OS like Windows 10 sees
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them so no it's not the same thing as having eight physical cores like at all
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but it can be a good way to make sure your CPU Cycles don't go to waste
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hopefully that was interesting I'm sure there will be more questions basically
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the gist of it is you don't have 8 cores but you have a much more effective way
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to utilize the four that you do have today we're highlighting the k7xx
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limited edition ruby red headphones from Mast drop of course Mast drop still has
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a bunch of other cool products you can check out in the link in the video
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description also and hopefully you guys know about Mast drop by now but if not
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the concept is actually pretty simple the more people commit to purchase a
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certain product the lower the price of that product actually goes the product
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we're showcasing today is the same spec-wise as the k7xx headphones that
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lonus reviewed last year you can check that video out up here the only real
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difference is that this run uses red accents on the ear cups and headband
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remember that this is a limited drop so if you want a pair you're going to have
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to act uh pretty fast these headphones were configured by mass drop and
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manufactured by AKG they're open backed headphones with large cushiony ear cups
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they feature a flat wire voice coil ver motion two-layer diaphragm genuine
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leather headband memory foam ear pads with vure covering a 2-year warranty
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covered by massdrop and you can order outside the US but a $25 fee will be
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assessed to all International orders so if you want to check them out and grab a
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pair of ruby red k7xx headphones head over to the link in the video
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description today anyways let me know what you guys
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thought about it comments down below don't forget to like it if you thought I did a good job dislike it if you thought
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I did do a bad job but don't forget to leave the constructive criticism down
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below I would like to know what I can do to be better also be sure to subscribe
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if you want to see more of our videos use our Amazon affiliate code to buy stuff cuz like that's cool I don't know
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that's pretty awesome also we have shirts not this one but they're in the
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link in the description down below you can check out some shirts that we have those are also pretty cool and we have a
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forum that's like awesome and has new software on it and looks super cool and
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like works better and stuff and we're still making tweaks to it there's definitely some things that can still be
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improved the store is a little a little broken it's my bad anyways check out
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this video there's more information up there about like cool computer stuff I
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haven't picked one yet uh but it'll be
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cool Daren put something cool up there
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feel free to put your own video okay bye