[T510] DPC Latency *LARGE PICS*

[f+m]

Hi all.

I'm about to buy a T510 soon. I'd use the machine for music production/on the stage where I'm dependent on low latency while using an external sound card via Firewire.
Only thing that worries me about the T510 is the DPC latency that was tested on this German site:
http://www.notebookcheck.com/Test-Lenov ... 431.0.html



It shows that some of the deferred procedure calls peaked at > 2000 mu s.

That's why I'd like to ask owners of a T510 (and T410 - I assume latency is similar on both machines) to run the DPC latency checker tool from http://www.thesycon.de/deu/latency_check.shtml (no installation necessary) and report the results.

Thanks a lot!
f+m

Admin note: Allowing somewhat oversized images, but please keep try to keep them around 50KB if possible

[Colonel O'Neill]

Also interested in knowing the DPC latencies, even though I don't do any professional audio of any sort.

[f+m]

anyone?

[darkwish]

This is from my T410:

[f+m]

thx! doesn't look that good :/

[Colonel O'Neill]

O_O

That doesn't look good at all!

[f+m]

D*mn.. being just one click away from ordering a T510.

What model do you have darkwish? do you have a dedicated graphics card? I've read somewhere that the driver of the dedicated Nvidia card might cause DPC latency problems, but this was related to an older Thinkpad model.

[darkwish]

Yes, it's a T410 with discrete graphics.

[Colonel O'Neill]

Is it a preloaded OS or a user-installed OS? Perhaps some driver isn't installed or installed properly?

I know my T400 gets DPC spikes most likely due to the Intel wifi driver.

[darkwish]

User installed OS.

[JonathanBe]

My T510 is only about 30 miles away, should arrive by Monday! I'll try to run the DPC latency test then. It'll be Win7-64, factory-installed, 4 GB RAM, discrete graphics.

Tried it on my X32 (2 GB, XP, ATI mobility radeon 16 MB AGP), running a dozen apps and about 200 browser tabs; the graph typically shows about 350. In several minutes it did once spike over 500. That's some sort of bad if a computer 2-3 generations newer is showing scores over 2,000.

[Colonel O'Neill]

Indeed...

My T400 hovers around 200 microseconds except for 1500-3000 spikes every ten seconds which is apparently due to a poor Intel wifi driver. I have yet to find a solution to this, although I hear regressing drivers way back does remedy the situation.

[JonathanBe]

My T510 is only about 30 miles away, should arrive by Monday! I'll try to run the DPC latency test then. It'll be Win7-64, factory-installed, 4 GB RAM, discrete graphics.

It was far more severe than I expected. At first, it was all around 200 ms, with a red (2000+) every 7 seconds or so. After starting Irfanview, I am now getting 5-8 red bars and 7-10 yellow bars (1000+ ms) appearing all the time (the rest are green bars at about 200 ms).

I then put on Process Explorer. It shows "System Idle Process" at 95% or higher throughout.

After closing application windows, I can still see 4-5 red bars and still 7-10 yellow bars at any time.

I have wireless turned off (with the switch at the bottom left).

I wonder if it has anything to do with UAC in Windows 7 ?

[brixvold]

I'll chime in with a nod to this thread in a different forum
http://www.diyaudio.com/forums/pc-based ... ay-go.html

And I really don't hope you expect snappy performance from any machine running a vista equivalent OS.

[Colonel O'Neill]

It was far more severe than I expected. At first, it was all around 200 ms, with a red (2000+) every 7 seconds or so. After starting Irfanview, I am now getting 5-8 red bars and 7-10 yellow bars (1000+ ms) appearing all the time (the rest are green bars at about 200 ms).

That really sucks.

Hopefully someone's posting this stuff on the Lenovo forums where an engineer might chance upon the situation.

UAC may be an issue, although I've never left UAC on long enough to find out

[rippeer]

I'm in the market for t410, so I thought I'd test my current machine for comparison.
I'm using a

z61t
Centrino Duo t2400 @ 1.83hz
2GB Ram
Audigy 2 ZS notebook
intergrated graphics,
windows xp - me install, or user instal if you prefer .

Anyways At first there was a spike into the Red every 30 seconds but after about a minute and half it stopped and I just about everything was around 200 with a spike to about 550-600 every 30 seconds.

[Colonel O'Neill]

I found out a long while ago that if I locked the CPU to it's highest multiplier, the DPC spike (every ten seconds for me) would top out near ~1800us. If I locked it to the lowest LFM multiplier, then the same spikes would hit almost 3500us.

Although locking the CPU to maximum frequency isn't the greatest solution, it keeps DPC lats in the yellow.

[JonathanBe]

I've now had practical experience. Using either WinDV or VirtualDub to capture DV (Digital Video format) video over the built-in firewire port in the T510, I experience hundreds of dropped frames. Say over 10% of the frames are dropped.

By contrast, my decade-old desktop Pentium-3 at 900 MHz, running Win2K, tends to drop one frame at the beginning of a tape, and then will not drop a single further frame in an hour of capture, in WinDV.

But of course lossily compressing (x70) the DV files to XVID is many times faster on the T510.

There could be alternative explanations. For example, Windows 7 supposedly does not support the DV format as well as Win2K did. Not known for a fact, just internet scuttlebut. Also, I have the x64 form of Windows, so it might be some 32- versus 64- bit incompatibility.

Firewire file transfer seems zippy enough, but no benchmark recorded.

[Colonel O'Neill]

Does it still drop frames if you lock the CPU to Highest using either Power Manager or some other tool? It could be Windows 7 throttling the CPU back and forth between power states, although I hear the Core family does throttling on-die or something of the sort.

[JonathanBe]

Does it still drop frames if you lock the CPU to Highest using either Power Manager or some other tool? It could be Windows 7 throttling the CPU back and forth between power states, although I hear the Core family does throttling on-die or something of the sort.

I've moved the DV capture station back to the basement where the 10-year-old desktop 900 MHz Pentium 3 computer lives. I did achieve another exploit there, though. While the WinDV capture was going on with no frames dropped on one firewire channel, I was able, using the free version of TeraCopy, to write the captured files on the other firewire channel back to an external HD at 10 to 18 MBps. Between the DV capture and file copying, CPU usage was about 80%. Using Win2K Copy, attempting to do that would freeze the DV capture. By contrast, on the T510, file transfer using built-in Windows 7 x64 Copy, from a firewire device through the computer out to a USB device, proceeded at the stately pace of about 2.6 MBps. Using TeraCopy for the same task got up to 10 MBps on the T510.

I'm glad I didn't trash that computer because it was "old".

[albo]

note that there was a LONG discussion about DPC latencies relating to T61 and T400 audio distortion a while back on the lenovo forums site (as much as I hate to direct people there - the moderators are CRAP).

[f+m]

Has someone tested yet if latency is improved when downgrading to XP?

[JonathanBe]

One possibility is an overly-cheap hardware implementation of Firewire 1394 on the T510. It's unfortunate to have to put "T" and "cheap" in the same sentence, but there you are. Certainly, in history, Firewire performance was highly dependent upon the chipset.

Another possibility is that Windows is at work. Maybe the process-slicing capability of Windows 7 (x64 in my case) simply doesn't assign a thick enough slice to Firewire activities. Which would be kind of ironic, because one of the selling points of Firewire is that it does not put a lot of strain on the CPU. I'm mentioning this because of a peculiar observation. If I put DPC latency checker on the taskbar, its screen quickly becomes filled with red, yellow, and yes a few green bars. But if I then run a highly processor-intensive appy in the foreground (Chess Assistant 7 running the 64-bit Stockfish engine, CPU usage in the 98% range according to Process Explorer) for a while, and then switch the window back to the latency checker, its screen is mostly green bars, with only one or two yellow or red bars. As that screen is sitting in front of me, with Stockfish still running full out, the screen begins to fill up with yellow and red bars. So is the UI of the latency checker actually causing the latency? Probably not, but it's almost like a quantum effect. Bwa-ha-ha.

[Colonel O'Neill]

Personally, installing the Intel Rapid Storage drivers over the Intel Matrix Storage drivers helped a lot. YMMV.

[JonathanBe]

Personally, installing the Intel Rapid Storage drivers over the Intel Matrix Storage drivers helped a lot. YMMV.

According to ThinkVantage SystemUpdate, Installation History, the Intel Rapid Storage AHCI Driver for Windows 64-bit version 9.5.7.1002 was installed April 7th. So my results were already improved.

There isn't much recent on DPC Latency (search term) at the Lenovo site. What there is, isn't very helpful or hopeful.

[bemymonkey]

Hi there, this problem isn't new - it's been around for a long time (check out the huge, huge thread about audio dropouts on the T60/61 in the Lenovo forums).

There's a few different factors here, which all contribute to spikes in DPC Latency. I'm listing them in order of severity...

1. nVidia GPU clock speed changes - Whenever nVidia GPUs change clock speeds (they do this on the fly, depending on GPU load), there's a huge spike in DPC Latency... off the charts in the DPC Latency Checker utility (something like 30k us). Solution: Lock the driver into a single "speedstep"... google rivatuner constant performance mode for more info.

2. Intel CPU speedstepping/C-States. These usually produce more subtle problems... usually not noticable as actual pauses, but as the music slowing down for a minimal duration. Switch to high performance mode in the power manager or RMClock or Windows power management.

3. Other misbehaving drivers... Stuff like WiFi or Bluetooth adapters are often to blame, however these usually don't cause audible problems, unlike 1. and 2.. In most cases they're only visible in the DPC Latency Checker, but don't actually cause dropouts or clicks/pops.

4. OS - XP is still the way to go for low latency audio applications... on the same (fully tweaked for lowest, most stable DPC latencies) hardware, I have 200-300us latencies on Windows 7, and 20-60us latencies on Windows XP Pro SP3.



In summary: Go for Intel integrated graphics (no problems there that I know of), put the CPU in full power mode and turn off anything you don't need. All on XP of course...

[omegatron]

This is really disappointing. I saw these good results on http://www.notebookcheck.net/Review-Len ... 368.0.html and assumed it was good to go:

To exclude problems caused by too long latencies when external devices are connected, we checked them with the DPC Latency Checker and can give the go-ahead here. The latencies always stay within a green field. You should test the external device in mind, i.e. an external sound card, beforehand in the notebook to make sure that it really works with the T410 without complaint.

But now I see people have problems even with these machines.

Is it only specific video or Wi-Fi cards that cause the problem? I don't really care which cards I get, as long as they prevent these issues.

Dell seems to be proactive about fixing these issues, but I don't see any similar responses by Lenovo.

http://en.community.dell.com/dell-blogs ... d-you.aspx
http://en.community.dell.com/dell-blogs ... omers.aspx

I'll chime in with a nod to this thread in a different forum
http://www.diyaudio.com/forums/pc-based ... ay-go.html

And I really don't hope you expect snappy performance from any machine running a vista equivalent OS.

After switching to Linux for audio several years ago, and never actually getting audio to work without dropouts or crashes .... ignore this guy.

I really don't hope you expect any kind of performance from any machine running a Windows 95 equivalent OS. After years of constant headaches and weeks of wasted time, I'm switching back to Windows 7. At least it boots reliably.

In summary: Go for Intel integrated graphics (no problems there that I know of), put the CPU in full power mode and turn off anything you don't need. All on XP of course...

"i dont have the nvidia video card, i got the intel hd graphics... its quite dissapointing cuase ive tried everything to find the root of this malfunctioning, its annoying cuase everytime you listen to music theres gaps of distortion"

http://forums.lenovo.com/t5/T400-T500-a ... m-p/271957

[Colonel O'Neill]

I dunno, the two T410's and T510's my friends bought have zero audio playback issues. None of them are particularly tech-savvy enough to know about DPC latencies, so I don't think they had the issue and remedied it themselves.

[omegatron]

I got a T410 i5-560M 2.66GHz, Intel Graphics 5700MHD - AMT, Intel Centrino Advanced-N 6200 (2x2 AGN), 4 GB PC3-8500, Win7 64-bit, 14.1 WXGA+, 500 GB 7200rpm. DPC checker looks like this after a few minutes:

http://i.imgur.com/fp1JH.png

After several hours of normal use, the maximum is 1500 us. Running it for many hours I saw as high as 120 ms, but this is probably due to strange events. So it seems fine to me, at least with the stock software.

[Colonel O'Neill]

Yeah, the DPC's seem to be more or less remedied. The one on the Lenovo Forums hasn't made a reappearance.