A blocksize problem about dax and ext4

[Cholerae Hu]

I used ext4 and set the blocksize to 4096, the mount command was silent.
Does it indicate that dax has already been enabled?

2015-12-24 10:47 GMT+08:00 Elliott, Robert (Persistent Memory) <
elliott at hpe.com>:

> > -----Original Message-----
> > From: Cholerae Hu [mailto:choleraehyq at 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
>
>
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