Messages in this thread | | | Date | Sun, 1 May 2016 10:28:54 -0700 | From | Christoph Hellwig <> | Subject | Re: [PATCH v5 0/2] ext4: Improve parallel I/O performance on NVDIMM |
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On Fri, Apr 29, 2016 at 12:38:20PM -0400, Waiman Long wrote: > From my testing, it looked like that parallel overwrites to the same file in > an ext4 filesystem on DAX can happen in parallel even if their range > overlaps. It was mainly because the code will drop the i_mutex before the > write. That means the overlapped blocks can get garbage. I think this is a > problem, but I am not expert in the ext4 filesystem to say for sure. I would > like to know your thought on that.
That's another issue with dax I/O pretending to be direct I/O.. Because it isn't we'll need to synchronize it like buffered I/O and not like direct I/O in all file systems.
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