Vista MMCSS - aneb degradace site kvuli MP3

[Fox!MURDER]

kdyz to tu nekdo vytah tak me zajimalo, jestli to v SP1 nejak vyresili ...

opet to dopadlo, tak, jak by clovek od M$ cekal reseni se nekona, jen je mozne nastavit jak moc to throttluje ... (ale uznavam, ze lepsi, nez puvodni stav ... )

For SP1 we were hoping for a complete overhaul of the MMCSS so that it ceased adversely affecting network performance, unfortunately what we’re getting is something about mid-way towards that. With SP1 it is now possible to control the amount of network throttling that MMCSS does, which means that throttling hasn’t been removed completely nor has it even been adjusted as far as the defaults are concerned. A quick test with Microsoft’s NTttcp tool shows the throttling level remains the same post-SP1 as it was pre-SP1 (roughly 70Mbps on a 1000Mb connection), which means SP1 will not be bringing any immediate relief. Furthermore there’s no GUI component (or real documentation) for this tweak, so users will be left to directly modifying the registry, a very uninviting situation.

What we do know is that this tweak only affects network receive performance, with a key apparently dictating the maximum percentage of the amount of network traffic allowed while the MMCSS is actively working. The key:

HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Network ThrottlingIndex

...defaults to 10 (for 10%) and can be adjusted to between 1 and 100, with the system requiring a reboot between adjustments. We did some quick testing with this key and were easily able to set it to 70%, which got us around 550Mbps of bandwidth through NTttcp, and we probably could have gone higher - especially on multi-core platforms.

tedy zminenej klic v registrech urcuje, jak moc se bude throttlovat.
na anandu sice pisou, ze jsou to procenta (ale bohuzel uz nepisou procenta ceho). podle toho, co pise Mark Russinovich na svym blogu (v prispevku kterej tohle vubec poprve vysvetlil) bych spis ocekaval, ze to bude pocet packetu za sekundu, ktery NDIS povoli.

It does so by issuing a command to the NDIS device driver, which is the driver that gives packets received by network adapter drivers to the TCP/IP driver, that causes NDIS to “indicate”, or pass along, at most 10 packets per millisecond (10,000 packets per second).

[Petrik]

Pro anglicky mene zdatne: Vista pri jakemkoliv prehravani medii (software pristupuje na zvukovku) omezi rychlost site na 10.000pps (packetu za vterinu) a tim zdegraduje vykon gigabitove site na 5%-20% (podle vykonu a nastaveni site). Pri vypnuti prehravace medii je vse opet vporadku....

10k pps dava pri MTU 1500 celkem slusnou propustnost 14MBps, takze budto to neni 10k pps, nebo je problem jinde.

EDIT: jo takze to tak je, mas pravdu, nezbyva nez dodat ze vytahnout z smb protoklu pod woknama vic nez 14MBps chce nejakou snahu i na XPckach, takze to zas takovy problem neni.

[Fox!MURDER]

10k pps dava pri MTU 1500 celkem slusnou propustnost 14MBps, takze budto to neni 10k pps, nebo je problem jinde.

EDIT: jo takze to tak je, mas pravdu, nezbyva nez dodat ze vytahnout z smb protoklu pod woknama vic nez 14MBps chce nejakou snahu i na XPckach, takze to zas takovy problem neni.

ma to jen dve mouchy ... 114Mbps (~14MBps) neni problem ze SMB vytahnout ani na XP ani ve Viste a netyka se to jen SMB protokolu ...

[Koudy]

kdyz to tu nekdo vytah tak me zajimalo, jestli to v SP1 nejak vyresili ...

opet to dopadlo, tak, jak by clovek od M$ cekal reseni se nekona, jen je mozne nastavit jak moc to throttluje ... (ale uznavam, ze lepsi, nez puvodni stav ... )



tedy zminenej klic v registrech urcuje, jak moc se bude throttlovat.
na anandu sice pisou, ze jsou to procenta (ale bohuzel uz nepisou procenta ceho). podle toho, co pise Mark Russinovich na svym blogu (v prispevku kterej tohle vubec poprve vysvetlil) bych spis ocekaval, ze to bude pocet packetu za sekundu, ktery NDIS povoli.

Tak tohle uz pomohlo lip.
Zatizil jsem jadra (rozbalovani rar archivu na disk ze ktereho se prehravaji mp3) a skutecne ten zvuk obcas vytuhnul behem te doby. Vraceni zavislosti MMCSS v registrech, zapnuti sluzby a uprava throttlingu na 80 mi zajistuje lepsi stabilitu.