RE: A blocksize problem about dax and ext4
-----Original Message-----
From: Cholerae Hu [mailto:choleraehyq@gmail.com]
Sent: Wednesday, December 23, 2015 8:36 PM
Subject: Re: A blocksize problem about dax and ext4
...
xfs will silently disable dax when the fs block size is too small,
i.e. your mmap() operations are backed by page cache in this case.
Currently the only indication of whether a mapping is DAX backed or
not is the presence of the VM_MIXEDMAP flag ("mm" in the VmFlags field
of /proc/<pid>/smaps)
Did you mean that I should make the blocksize bigger until the mount
command tell me that dax is enabled?
To really use DAX, the filesystem block size must match the
system CPU's page size, which is probably 4096 bytes.
---
Robert Elliott, HPE Persistent Memory