对于实时应用程序，SetFileBandwidthReservation仍然无法使用 [英] SetFileBandwidthReservation still is unusable for realtime apps

问题描述

我有为实时视频应用保留磁盘带宽的要求。

正如我所见，虽然在Vista时宣布目前仍然是Windows 7实际上并没有提供这样的功能。这里是我找到的信息：

1。从我的测试中，通过SetThreadPriority和SetPriorityClass设置线程/进程优先级不会影响实际的I / O速率。我无法看到运行两个具有不同优先级的磁盘密集型测试程序的区别。

2。我希望SetFileBandwidthReservation可以提供帮助，但我在实践中发现它取决于驱动程序支持。测试AHCI和MegaRAID SCSI驱动程序显示不支持此调用。 "优先提示"也是如此。驱动程序使用NtQueryInformationFile
（FileSfioReserveInformation或FileIoPriorityHintInformation）调用返回错误。

3。此外，在WDK中查找一些信息我发现无法为用户应用程序引发优先级提示。它可以是正常的或背景的。可以仅为分页操作请求最大优先级，而不是用户文件I / O. 

如果我错了可能有人描述系统（磁盘驱动程序） ）配置允许增加应用程序I / O优先级超过其他应用程序（包括Windows文件服务器）？

解决方案

是的，它需要支持驱动程序。

I have the requirements to reserve disk bandwidth for real time video app.

As I see although announced at Vista time currently Windows 7 still does not provide such such features in reality. Here the information I found:

1. From my tests setting thread/process priorities via SetThreadPriority and SetPriorityClass does not affect real I/O rates. I was not able to see the difference running two disk intensive test programs with different priorities.

2. I had a hope that SetFileBandwidthReservation could help, but I found in practice it depends on driver support. Testing AHCI and MegaRAID SCSI driver shows this call was not supported. The same thing with 'priority hint'. Drivers returns error with NtQueryInformationFile (FileSfioReserveInformation or FileIoPriorityHintInformation) calls.

3. Moreover, looking for some information in WDK I see that priority hint could not be raised for user application. It could be either normal or background. Maximum priority could be requested only for paging operation, not by user file I/O. 

If I'm wrong could someone describe system (disk driver) configuration that allow to increase application I/O priority over other apps (including Windows File Server)?

解决方案

Yes, it need the driver supported.

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