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Mark Russinovich On Vista Network Slowdown
koro666 writes "In his latest blog post, Mark Russinovich analyzes the network slowdown experienced by some users when playing multimedia content. 'Tests of MMCSS during Vista development showed that... heavy network traffic can cause enough long-running DPCs to prevent playback threads from keeping up with their media streaming requirements, resulting in glitching. MMCSS' glitch-resistant mechanisms were therefore extended to include throttling of network activity. It does so by issuing a command to the NDIS device driver... [to] pass along, at most 10 packets per millisecond (10,000 packets per second)... [T]he networking team is actively working with the MMCSS team on a fix that allows for not so dramatically penalizing network traffic, while still delivering a glitch-resistant experience.'"
Once again, over-complication and stupid engineering lead to a humiliatingly bad operating system. It's obvious it didn't receive a modicum of real testing.
Sam ty sig.
But don't let logic or common sense get in your way.
Because they're not Vista. Think of Vista as the operating system that the movie and music industry produced.
Because the standard Ethernet frame size is about 1500 bytes, a limit of 10,000 packets per second equals a maximum throughput of roughly 15MB/s. 100Mb networks can handle at most 12MB/s, so if your system is on a 100Mb network, you typically won't see any slowdown. However, if you have a 1Gb network infrastructure and both the sending system and your Vista receiving system have 1Gb network adapters, you'll see throughput drop to roughly 15%."
That is one of the dumbest things I have heard in a while. Let's see:
What an over-engineered non-solution to what should have been a non-problem in the first place. Microsoft is supposed to employ some of the smartest engineers in the world: can none of them optimise their code?
I find this totally interesting. It goes to the heart of what is wrong with Microsoft these days... All seperate groups of folks, not talking to each other, to try and do "what is best" for the user, and then totally stomping on each other. Instead of really looking at thread management and optimising the kernel, they cludge together something to make multi media work by simplying saying "in certain situations, I can't guarentee the thread because of a crappy kernel, so I am going to tell everyone else to slow down".
It is these sorts of things and things like the teams and teams debating the "Shutdown Menu" in Vista that are really showing Microsoft needs to really change if they are going to survive. It amazes me how a bunch of open source developers with all their own agendas do a better job then a bunch of folks all paid by the same company. Of course then there is Apple of an example of a group that shows you can pull it off and still all look like the same organisation.
D.O.U.O.S.V.A.V.V.M.
I haven't been really on the lookout for it, but I haven't seen any posts explaining that as the cause. I'd expect if that really were the cause, there'd be a much bigger outrage from people and it would have blown up and I'd see articles on it whether I wanted to or not. I don't really see any useful DRM techniques for unprotected MP3s anyway. There'd really be nothing that MS could do with that sort of information.
However, this actually does make sense. In all honesty, they probably would have worked on a better answer than cutting back on networking, but with the time crunch on releasing it, they probably cut corners here and there (and by probably, i mean definitely and by here and there, i mean everywhere). They probably viewed this as an acceptable cut for the time being because for a majority of users, they use very little of their networking bandwidth. If its just a PC connected to the internet, they'd most likely never notice. The only time this would be an issue is for heavy network usage, which would normally only occur on work-related machines because let's face it, aside from geeks and techies, not many people have systems set up that max out their network bandwidth, so, if they were work-related machines, well, they probably wouldn't be playing that much music to begin with.
I'm not a MS shill, though I don't assume everything they do has evil intentions. We have to admit that they are great code writers, just not the best. Just because they do shady things here and there (mostly in business practices however) doesn't mean everything they do is evil. This was a problem they ran into and they made a workaround that would only affect a relatively small amount of their users. They were probably hoping no one would notice it at all until they either A) had a fix or B) just let it go because maybe no one would notice it.
Remember, this wouldn't really slow down your internet unless you have an *extremely* high bandwidth and even then, bottlenecks on the information before reaching you would probably still mask the problem. This is only an issue on system that have heavy network usage on some sort of intranet or other type of local area network, because these would account for the majority of networks that could even use a decent amount of your possible networking bandwidth.
"MMCSS is the Multimedia Class Scheduler Service, which a new feature in Vista -- it is not in 98/95/2000/ME/XP. That's why."
Winodws XP -- can play an MP3 file and video file at the same time with no reduction in network speed.
Vista -- same computer, same hardware, -- major reduction in network speed.
In other words, Microsoft tried to "fix" something that wasn't broken.
http://www.ubuntu.com/getubuntu/download
If this isn't "defective by design", I don't know what is.
As goes without saying, arbitrarily throttling one particular task, at some arbitrary level, is the wrong thing.
Perhaps this could go in Wikipedia under "Kludge"?
Shouldn't any computer powerfull enough to run Vista be "powerful enough to not need such a draconian throttling?"
Put identity in the browser.
it was an IMPOSED, HARDCODED limit WITHOUT ASKING the user. They could just add a registry entry of "maximum network packets per millisecond when playing multimedia files" or something.
Microsoft has a long history of hardcoding stuff without thinking of power users. Remember the 10-limit for open TCP connections per program? They did this because viruses and malware open many TCP connections. "Hey, what about P2P?" "What's P2P?".
I'd had two CPU's and Gigabit Ethernet for three years by the time that Vista was on sale to the public. That's not simply "short-sighted with respect to today's systems", that's a total let down to businesses who have high-performance workstations.
> tweaked Windows for profit instead of to improve efficiency or user experience
Did you read the article? It was obviously tweaked to improve the "user experience"; the painful difference between OSS and this being that Microsoft arbitrarily decided for all of Vista's users what "user experience" they would like to experience (i.e., skipless media playback as opposed to maximum network performance). There were bugs in Microsoft's solution, but there are also bugs in OSS.
OSS projects, however, are (usually) much less dictatorial in deciding what the user wants; they can't be, actually, because if he doesn't like what they give him, he can just fork-and-run.
Just what is a "glitch-resistant experience" ? Before he was in M$ payroll, Mark would have called this something else. Sorry, but his "technical authority" value, that Microsoft are hoping to use to explain away their bugs, has lost all value now he's making their excuses for them.
I don't think that you could convince Microsoft to change their code to allow software who's primary usage is piracy, including that of Microsoft products. In fact, I think this particular behavior was indeed by design.
Well.. maybe. Or Maybe not. But Definitely not sort of.
As written in the article...
Besides activity by other threads, media playback can also be affected by network activity. When a network packet arrives at system, it triggers a CPU interrupt, which causes the device driver for the device at which the packet arrived to execute an Interrupt Service Routine (ISR). Other device interrupts are blocked while ISRs run, so ISRs typically do some device book-keeping and then perform the more lengthy transfer of data to or from their device in a Deferred Procedure Call (DPC) that runs with device interrupts enabled. While DPCs execute with interrupts enabled, they take precedence over all thread execution, regardless of priority, on the processor on which they run, and can therefore impede media playback threads. They're saying that every packet received causes an interrupt request, which causes the CPU to get loaded at high transfer speeds.
Apparently they haven't heard of interrupt moderation or polling, technologies that are used by network cards to offload the CPU.
Even my Marvell semi-hardware (I think) Gigabit on-board network card used about 14% CPU (Barton 1833Mhz) when transferring files at about 45Mbps.
I don't know, everything seems really stupid, and I'm not sure it's just a "bug", or their description is just a part of what really happens behind the scene.
I think it's right to at least pose the question, though. Before, Mark was a Windows expert working independently, and was able to voice opinions as he saw fit. Now he's a Windows expert being paid by the company that makes Windows - the very success of Windows Vista will dictate how long his job lasts. He now has an interest in assuring customers and investors that things aren't as bad as they might be. Now, it's all about the bottom line. Of course, he's built up a lot of trust amongst the community, trust which MS themselves are now paying money for. Whilst we can continue to trust him, until proved otherwise, it's not wrong to least ask the question.
It's not a flawed implementation, its defective by design (and I don't mean DRM'd, I mean literally).
On Linux, with the CFS and/or SD schedulers, if your nice levels are set correctly, sound (MP3) will play just fine with your processor(s) pegged at 100. Heck, forget about sound; you can run multiple Quake 4s with high-speed LAN transfers in the background, and everything works just fine (network transfers slowdown slightly, Quake 4's FPS scales down linearly with the number of sessions running, but there are no "hitches" or "glitches", and everything runs smoothly).
A common Microsoft approach to problems with Windows is to create a new daemon (oh, excuse me, Service) that "regulates" the offending behavior. This is not the correct way to fix these problems; rather, there are underlying issues that need to be resolved.
You say:
The MMCSS is for improving multimedia performance on EXTREMELY heavily-loaded processors. I use XP, and my PC is occasionally heavily loaded with a dozen threads, and in those cases I occasionally experience glitches. Thus, I have to manually adjust thread priorities, but it's annoying anyway.
I say it's not about manually adjust thread priorities, or creating a Service that will automatically (dynamically or not) do that for you. Rather, you should have a kernel that better manages multitasking in processor starved scenarios. There's no reason that a particular program running at a particular nice level shouldn't demand a minimum CPU percentage, which for stuff like playing MP3s cannot possibly be much.
WhiteWolf666 an exBush supporter. All you new-school,compassionate,save the children Republicans can rot in hell
So, basically the GP poster was right: 1% goes to WGA.
GPG 0x1B479C78