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Playing Music Slows Vista Network Performance?
An anonymous reader writes "Over the months since Vista's release, there has been no doubt about the reduced level of network performance experienced compared to Windows XP. However, some users over at the 2CPU forums have discovered an unexplained connection with audio playback resulting in a cap at approximately 5%-10% of total network throughput. Whenever any audio is being sent to a sound card (even, several users report, while paused), network performance is instantly reduced. As soon as the audio is stopped, the throughput begins to climb to its expected speed. It's a tough one for users — what do you pick, sound or speed? So much for multi-tasking."
Well we do know that there are new API's in Vista that allow reservations of bandwidth for devices (like disk drives) and that media player does indeed make use of them (this has been demonstrated at events like Tech-Ed and Mark Russinovich's talks have contained demonstrations of this as well). I can't imagine that they purposefully tried to reserve network bandwidth though when the files are local on your hard drive. You can see why they would reserve some hard drive bandwidth though; as the GP said it is to provide skip-free audio and is indeed a new Vista feature. Sounds like they either have a bug with it where it reserves network bandwidth when it doesn't need to, or it is something to do with it having to reserve a certain percentage of the total number of interrupts regardless of which device is being triggered?
Back in 2003, my ethernet card (under debian) would *only* work if I was also playing music. Granted, that was because my ethernet card was broken and didn't properly send interrupts (so the sound card was sending them, and the ethernet driver was being activated when it noticed that it had an interrupt too), but it was still pretty awesome. Perhaps Vista has a similar problem... =)
Vista does put in place measures to ensure that multimedia applications have a higher I/O priority than other operations.
Whoever did these tests should try again with the Multimedia Class Scheduler service disabled to see if it makes a difference. Also they need to try multiple multimedia applications (WMP would benefit from MCS, but other multimedia apps may not yet).
Wine have just moved the direct 3d layer from glx over to wgl, this should mean that it will compile on windows any time soon.
And as soon as it gets directX 10 support you should be able to run the DX10 only games on XP.
thank God the internet isn't a human right.
Except that the Windows Audio service depends on MMCSS, so if you try to disable the Multimedia Class Scheduler, you can't listen to any music at all.
For the record, I just tested this bug on Vista Small Business and found the same result. If I load WMP, I can still utilize ~35% of the network, but as soon as I start a song, or have a song paused (or even stopped but still loaded) it drops down to 8-10% every time.