Metformin
Gawd
- Joined
- Feb 27, 2013
- Messages
- 690
I have a choice between a x3430 (4 cores,4 threads) and a x3440 (4 cores,8 threads). Just wondering if the extra $10.00 is worth it for the x3440.
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If you do more than 4 threads with heavy CPU load. then yes. depending on code inefficiency it can give you a boostaround of 10-25% at 8 threads
If you do 4 or less heavy CPU threads, then HT will degrade your performance. with around 5-10%
a quick and dirty benhmark
Cinebench R15 4 threads ( I7 920 4C/8T)
With HT enabled: 305-307CB
With HT disabled:: 335-337
7zip benchmark 4 threads 32mb (I7 3770 4C/8T)
with HT enabled 177727KBs / 195486KBs
with HT disabled 18270KBs / 201053KBs
Whenever your CPU can accept more threads than it have in physical hardware you risk threads conflicts, when you don't utilize the CPU fully.
is the same with AMD CMT design since it only has 1 fpu per two cores ( and therby accepting 2 threads to 1 FPU)
if you do go for a CPU with HT and are gaming alot (typical utilize lower numbers of threads" you can use my Project Mercury to disabled HT for you main application and gain a slight CPU performance boost
Also the more inefficient your software is coded. the more gain you get with hyper threading and the less penalty. Which is the reason some highly optimized math libraries disable/circumvent HT ( Linpack among others)
Have you any real proof to your wrong statements?.. those numbers are based on what?.. you are spreading lot of misinformation there without any real base.. with fabricated numbers, last time I did the same test last year I got completely different result to what you state.. so you are saying HT degrade performance? what a joke.. it's a funny fact that even with HT ON and running the benchmark with 4 Threads consistently have better result because the other 4 threads can do the additional job while only 4 threads are working to 100%..
The guy above can't be fucking serious comparing actual cores with mix of real and logical cores (hello,OS scheduler!).
I mean, for fuck's sake, he just compared fake i5 with fake i3 and concluded that fake i3 is, surprise, slower, pretty much.
The guy above can't be fucking serious comparing actual cores with mix of real and logical cores (hello,OS scheduler!).
I mean, for fuck's sake, he just compared fake i5 with fake i3 and concluded that fake i3 is, surprise, slower, pretty much.
So of course SvenBent is going to show us the worst-case performance with a first-generation Core with Hyperthreading.
It would be nice if someone could run the same benchmark with a 6700k to show what 'm talking about. Anyone got five minutes and a 6700k?
Its not for worstcase reason. I did show a 3770 in my first post as well. ( however only in text)
the reason is that the 930 is my work computer im sitting with at of this moment
The 3770 i my home computer.
Please don't directly or indirectly imply a personal bias accidental or not. Its already hard to explain the issues correctly for people that tend to put fingers in their ears and go LALALLAA IM RIGHT YOU ARE NOT...
I Wholehardheartedly agree it very depending on sitatuion and software ( which was my starting argument) and that test with an newer architecture would be interesting.
Haswell added more execution units to improve hyper-threading performance, and Skylake added faster cache AND one more execution unit. Get back to me with 6700k results if you want to be taken seriously in your analysis of HT impact in the modern world.
I wanna see these negative returns on a modern processor with HT that this guy is talking about.
Ive got a 6600k @ 4.5. Ill run it tonight. Someone here has a 6700k @ 4.5 as well. I'm not holding my breath to see the 6700k to come in slower because it's not gonna happen, not never.
Yes, you, because you are comparing i5 with i3 and finding out that i3 is slower. That is the only thing your screenshots show.Wait what? Me or Araxie ? im not sure i follow your statements
anyway for Araxie again here is a bit more "evidence"
The important setting in WPrime
WPrime I7 930 HT enabled
WPrime I7 93- HT disabled
7zip 930 HT enabled
7zip 930 HT disabled
all getting a boost when it only using 4 threads and disabling HT so you only have the 4 physical cores they can go to.
now off cause had i used 8 threads enabling HT would be beneficial.
Again in this topic its about 45nm Xeons with hyper threading i believe the closes I7 architecture to that is indeed the 900 series.
correct me if I'm wrong. I'm simply going but what looks more identical on the Intel ARK
Yes, you, because you are comparing i5 with i3 and finding out that i3 is slower. That is the only thing your screenshots show.
And yes, i see your point, but you could at least show actual real world low-thread count workloads instead of making it look plain stupid with embarrassingly parallel synthetics.
I'm sorry i don't understand at all what you are trying to say with in i3 and i5. I'm running this on an old I7 only enabling and disabling HT. Where do you get this I3 and I5 from ?
If you have any suggestion to software that are better to use I'm all ears but 7-zip is very real world to me. And in many situations i cant utilize 8 threads with 7-zip due to memory requirements.
it takes around a bit more than 16GB of ram per 2 threads to use. So often 7-zip is running with 2 or 4 threads only. currently using affinity to avoid Threads conflicts from HT give me a boost that can shave of a day or 2 of the work.
I simply choose software I knew i could set the threads on and that was not bottle-necked by other system parts to show the effect.
I'm very open for debate on this but I have done tons of tests and benchmark on this over both Intel and AMD system (SMT and CMT) when i implanted the features to avoid this performance drop in my Project Mercury software.
This is an old benchmark from august 2015 on AMD CMT desing with handbrake 2 threads ( more than 2 threads reduced video quality microminimally)
afiinity all = 30-40fps
afiinity 0&1 = 26-30s fps
affinity 0&3 = 38-39fps
now in this case i used affinity to control and avoid the CMT fallbacks
and the FPS increased from 30-40 from to 38-39
Putting the 2 threads on the same CMT unit and thereby forcing the thread conflicts 100% of the time the performance dropped to 26-30fps
This is off cause very artificial but is to show the big difference between sharing a physical core and having one each.
Put again if you know about some software that use only 2-4 CPU heavy threads that yo find more applicable, just drop a link and i will look into it.
Your old i7 doesn't count for a relevant discussion though. Most especially when you place a limit in the software. Handbrake, for instance, will use just about every core you can give it. I call BS on your decreases video quality, as well. That makes zero sense.
As far as I know, there isn't a single piece of modern software (where speed matters) that isn't multi-threaded. Your OS, web browsers, games, and productivity software are all multithreaded now.
You jump around so much. Are we talking about HPC or standard desktop computing?
I would like to see an example of your claims about reduced video quality. Encode a 30 second video with the same quality settings. One in the way you say degrades video quality, and one in the way that you believe is the superior method.
Also, as you describe, that sounds like a downfall of the codec used, rather than a problem with using more threads. You describe an issue that points to poor programming.
I would like to see an example of your claims about reduced video quality. Encode a 30 second video with the same quality settings. One in the way you say degrades video quality, and one in the way that you believe is the superior method.
Keep in mind that threaded performance of many apps is also affected by your underlying storage (Depending on workload) 3D compositing makes heavy use of threads, but you can quickly saturate a spinning drive or even a single SSD with metadata generation with that workload.
Using multiple SSDs is necessary at that level to support full performance for every thread.
thats what i recalled but wasn't sure. I thought HT has some major improvements with removing that penalty the 920 had where HT really doesn't have a pentalty in those work cases anymore.But he's right. HT can sometimes take a performance hit when it's under-utilized. This is why Battlefield 3 and 4 took a small performance hit with HT enabled on a Core i7 (Core i3 saw massive speedup), because the game has four major threads.
But it doesn't happen in every application. And most of the time you won't notice it.
Also, newer CPUs have had better-optimized HT scheduling to counter these negative effects, along with faster cache to mask any performance impact. So of course SvenBent is going to show us the worst-case performance with a first-generation Core with Hyperthreading.
It would be nice if someone could run the same benchmark with a 6700k to show what I'm talking about: there should be a lower performance hit. Anyone got five minutes and a 6700k?
In the meantime, there is this set of gaming benchmarks:
Gaming benchmarks: Core i7 6700K hyperthreading test
OF course, the rest of these benchmarks in this thread are bullshit because we're restricting threads on massive-multithreaded benches. And also, the impact is less than 10 percent in most cases. This is just to demonstrate what can happen.
And then if you really want to get abstract and crazy, 2 CPU systems are faster than 4-CPU systems (depending on application).
Eg: an enterprise database will run faster on a 2 CPU system with flash storage than it will on a 4 CPU system with the same flash storage.
The NUMA overhead with the 4-socket system is quite the bottleneck and requires a ton of process/thread pinning to make it efficient.