Problem with FILE_SYNCHRONOUS_IO_NONALERT

NTFSD
1

Hi all,
When I specify FILE_SYNCHRONOUS_IO_NONALERT in ZwCreateFile and call ZwWriteFile, the system performance degrade tempestuously, and some applications do not respond. Why did this happen and how can I avoid this?

This only happen when ZwWriteFile is called frequently and a large number of IO.

Thanks & regards.

2

Will it be better if I create a thread to do the WriteFile, and waite the WriteFile return?

3

I’m sure people would like to help, but you haven’t asked anything
meaningful yet.

Which files are you setting this bit to read from? Is this a filter? A file
system? A Minifilter? What are you trying to achieve? How does this ZwWrite
affect the applications which hang? Is this just an application issuing
reads?

4

My driver is a disk upperfillter. I need to write a log file in my driver and I hope the data is written to disk synchronously. The file is created by myself. Many applications will hang, it seems that my driver has blocked disk IO.

5

Without this flag it will cause a system crash.

6

If this log is not written, I will not handle the disk IO. But I find many file system drivers are useing this flag, and they seems to perform well.