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  Message 1 of 7  
16 Aug 17 06:55
vishal ghadge
xxxxxx@gmail.com
Join Date: 09 May 2017
Posts To This List: 7
Verify I/O priority values

I am trying to set I/O priority by below methods, In user mode:Method 1 1. CreateFile() 2. SetFileInformationByHandle(FileIoPriorityHintInfo) 3. ReadFile() In Minifilter driver: Method 2 1. FltCreateFile() 2. FltSetIoPriorityHintIntoFileObject() 3. FltReadFile() When I set priority using method 1 and analyse procmon logs, priority values got reflected as i set in SetFileInformationByHandle() API. When I set priority using Method 2 and analyse procmon logs, Priority values are not shown in procmon logs. In method 2, How do I verify that priority values given by me are reflected or not? Why procmon not showing priority values? Thanks in advance.
  Message 2 of 7  
16 Aug 17 11:56
Slava Imameev
xxxxxx@hotmail.com
Join Date: 13 Sep 2013
Posts To This List: 251
Verify I/O priority values

What is the altitude for your filter? Is it less than procmon's altitude which is by default 385200 ?
  Message 3 of 7  
17 Aug 17 01:43
vishal ghadge
xxxxxx@gmail.com
Join Date: 09 May 2017
Posts To This List: 7
Verify I/O priority values

>>What is the altitude for your filter? Is it less than procmon's altitude which is by default 385200 ? I tried both by keeping procmon below and above my driver. In both cases I don't see priority values.
  Message 4 of 7  
23 Aug 17 06:02
vishal ghadge
xxxxxx@gmail.com
Join Date: 09 May 2017
Posts To This List: 7
Verify I/O priority values

I did below tryout, Instead of calling FltReadFile() I tried to read file using FltPerformSynchronousIo() API. When I set priority values using FltSetIoPriorityHintIntoCallbackData() while issuing IRP_MJ_READ using FltPerformSynchronousIo() API, this priority values gets reflected and procmon shows that priority values. Now I am really confused, Why procmon not shows priority values when I set it using FltSetIoPriorityHintIntoFileObject() API? Is procmon unable to read priority values from File Object? or priority values set in File Object are not properly convey to file system via Filter Manager? any help would be greatly appreciated.
  Message 5 of 7  
29 Aug 17 05:44
vishal ghadge
xxxxxx@gmail.com
Join Date: 09 May 2017
Posts To This List: 7
Verify I/O priority values

Anyone from Microsoft can provide inputs?
  Message 6 of 7  
29 Aug 17 12:30
Scott Noone
xxxxxx@osr.com
Join Date: 10 Jul 2002
Posts To This List: 908
List Moderator
Verify I/O priority values

Sounds like it's either a bug in FltMgr or a bug in Process Monitor. I would throw in a lower filter that calls FltGetIoPriorityHint and prints the results. -scott OSR @OSRDrivers wrote in message news:102949@ntfsd... Anyone from Microsoft can provide inputs?
  Message 7 of 7  
08 Sep 17 01:50
vishal ghadge
xxxxxx@gmail.com
Join Date: 09 May 2017
Posts To This List: 7
Verify I/O priority values

Thanks a lot, Scott. I did tryout suggested by you and in the lower filter, it shows proper priority values which I set in the upper filter. Maybe procmon not able to read/show priority values from File Object.
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