Re: Local DoS through write heavy I/O on CFQ & Deadline

From: Chris Friesen
Date: Thu Oct 18 2012 - 18:14:02 EST

On 10/18/2012 03:28 PM, Jan Kara wrote:

Yeah, ionice has its limitations. The problem is that all buffered
writes happen just into memory (so completely independently of ionice
settings). Subsequent writing of dirty memory to disk happens using flusher
thread which is a kernel process and it doesn't know anything about IO
priority set for task which created the file. If you wrote the file with
oflag=direct or oflag=sync you would see that ionice works as expected.

Has anyone looked at storing the ionice value with the buffered write request such that the actual writes to disk could be sorted by priority and done with the ionice level of the original caller?

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