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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