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Calypto

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Discussion starter · #1 ·
While I'm pleased with the increased performance of my new Ryzen CPU, I'm extremely displeased with the input lag of this system. I've done just about everything in BIOS and Windows to decrease my DPC latency, yet it's still unchanged. The only misbehaving driver is the nvidia one, yet on my old Intel system I had the same problem but the average DPC latency was around .6us, and eventually I got it down to .4us once the nvidia driver got its **** together, so I know it's not the main culprit.

Specs:
Ryzen 2700 @ 4.0GHz
Gigabyte Ultra Gaming X470
2133MHz RAM (I can't get it to overclock without blue screens, another issue for another thread)
Windows 7 Home Premium via MBR

My average latencies on my new Ryzen system:
Image


My average latencies on my old Intel system:
Image


What is the issue? Do I have a bad motherboard? Is it RAM? Is it Ryzen's architecture? I really want to love this new system, but I simply can't.
 
#2 ·
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#4 ·
3.5 microseconds average is hardly going to be problematic and almost certainly isn't going to be responsible for any input latency you are perceiving.
 
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#6 ·
I know how long a microsecond is and have a good idea of the number of interrupts a system has to process.

There is no issue implied by a 3.5 microsecond average interrupt to process latency, which is not abnormally high, and even if you are a CS:GO player targeting 300 fps, I have difficulty imagining the input latency you are experiencing is directly related, though perhaps they are symptoms of the same issue.

On an academic level, you are never going to get a Ryzen to the same latency floor as a mainstream Intel platform. They are typically clocked lower and require more cycles to access memory or I/O. Shouldn't be a big enough issue to be perceptible and even if you are exceptionally sensitive to such things, I'd double check everything and rule out other possible sources of latency before putting it down to a platform issue.
 
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Discussion starter · #7 · (Edited)
When I was getting the DPC latency down on my old Intel system, I instantly felt the difference after deleting my USB3 drivers and enabling MSI mode for applicable drivers. Once you get your DPC latency down to how I had it, it's easily noticeable. At this point I have no other tweaks remaining to get my DPC latency down. Funny enough, even with the IPC gains and 4.0GHz clock speed, my i5-3330@3.0GHz was able to go down significantly lower than what I have on this new system, which is extremely annoying to me.

The problem with my issue is that any DPC latency thread that comes up in search results involves people getting stuttering/microstuttering, whereas I'm having high average DPC latency but relatively low spikes. It's extremely frustrating because I have nothing to compare my results with. If you have a Ryzen system, I'd love to see what you get. I don't know if I have software/hardware conflicts or am simply at the mercy of the architecture.

Anyway, if you don't think it's the architecture, then what is it?
 
#8 ·
Blameless said:
I know how long a microsecond is and have a good idea of the number of interrupts a system has to process.

There is no issue implied by a 3.5 microsecond average interrupt to process latency, which is not abnormally high, and even if you are a CS:GO player targeting 300 fps, I have difficulty imagining the input latency you are experiencing is directly related, though perhaps they are symptoms of the same issue.

On an academic level, you are never going to get a Ryzen to the same latency floor as a mainstream Intel platform. They are typically clocked lower and require more cycles to access memory or I/O. Shouldn't be a big enough issue to be perceptible and even if you are exceptionally sensitive to such things, I'd double check everything and rule out other possible sources of latency before putting it down to a platform issue.
Click to expand...
Calypto said:
When I was getting the DPC latency down on my old Intel system, I instantly felt the difference after deleting my USB3 drivers and enabling MSI mode for applicable drivers. Once you get your DPC latency down to how I had it, it's easily noticeable. At this point I have no other tweaks remaining to get my DPC latency down. Funny enough, even with the IPC gains and 4.0GHz clock speed, my i5-3330@3.0GHz was able to go down significantly lower than what I have on this new system, which is extremely annoying to me.

The problem with my issue is that any DPC latency thread that comes up in search results involves people getting stuttering/microstuttering, whereas I'm having high average DPC latency but relatively low spikes. It's extremely frustrating because I have nothing to compare my results with. If you have a Ryzen system, I'd love to see what you get. I don't know if I have software/hardware conflicts or am simply at the mercy of the architecture.

Anyway, if you don't think it's the architecture, then what is it?
Click to expand...
Hello guys.

You both are right and wrong in some regards...

Removal of old drivers, or disabling of unused devices - especially with crappy drivers - may improve system performance, while the DPC latency will decrease as a side effect.

However since DPC latencies are measured in microseconds, average values are actually NOT a problem. What is a problem when a driver or a process cause a spike in latency - when microseconds turn into miliseconds.

Lets say that DPC Latency measures average latency 60-120 microseconds. Thats perfectly fine, even when some people will tell you tweaks how to get it down to less than 30. In some cases they even proposed steps which will not help to decrease the latency, but those will make measurings less accurate (everything regarding disabling of HPET).

Check pictures here:
https://www.thesycon.de/eng/latency_check.shtml

You can clearly see where the LAG is present and measurable, and where is everything OK, despite high average latency.
 
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#9 ·
I previously had a Samsung 960 Evo SSD driver that was causing pretty significant dpc latency spikes, although a newer driver fixed that for me.
 
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Discussion starter · #10 ·
Ok, I disabled a CCX and just as I suspected, my DPC and interrupt to process latencies significantly went down. I guess Ryzen's architecture combined with the Windows scheduler aren't conducive for low latency applications such as audio or higher-level FPS gaming. That is extremely unfortunate as I really wanted to stick it to the Jews at Intel.

I included the 2700 in the picture just to prove that I am not lying, as I've been accused of being an Intel shill (not here), which is ridiculous. My CPU is at 4GHz according to HWMonitor.
Image
 
#12 ·
Calypto said:
Ok, I disabled a CCX and just as I suspected, my DPC and interrupt to process latencies significantly went down. I guess Ryzen's architecture combined with the Windows scheduler aren't conducive for low latency applications such as audio or higher-level FPS gaming. That is extremely unfortunate as I really wanted to stick it to the Jews at Intel.

I included the 2700 in the picture just to prove that I am not lying, as I've been accused of being an Intel shill (not here), which is ridiculous. My CPU is at 4GHz according to HWMonitor.
Image
Click to expand...
But it increased maximum measured values. Can you please provide screenshot of the LatencyMon? Dont run any other program while running the benchmark.
 
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Calypto
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