On Mon, May 04, 2020 at 05:20:16PM -0700, 'Ira Weiny' wrote: > From: Ira Weiny <ira.weiny@xxxxxxxxx> > > Linux 5.8 is slated to have STATX_ATTR_DAX support. > > https://lore.kernel.org/lkml/20200428002142.404144-4-ira.weiny@xxxxxxxxx/ > https://lore.kernel.org/lkml/20200504161352.GA13783@magnolia/ > > Add the text to the statx man page. > > Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx> Have I sent this to the wrong list? Or perhaps I have missed a reply. I don't see this applied to the man-pages project.[1] But perhaps I am looking at the wrong place? Thank you, Ira [1] git://git.kernel.org/pub/scm/docs/man-pages/man-pages.git > --- > man2/statx.2 | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/man2/statx.2 b/man2/statx.2 > index 2e90f07dbdbc..14c4ab78e7bd 100644 > --- a/man2/statx.2 > +++ b/man2/statx.2 > @@ -468,6 +468,30 @@ The file has fs-verity enabled. > It cannot be written to, and all reads from it will be verified > against a cryptographic hash that covers the > entire file (e.g., via a Merkle tree). > +.TP > +.BR STATX_ATTR_DAX (since Linux 5.8) > +The file is in the DAX (cpu direct access) state. DAX state attempts to > +minimize software cache effects for both I/O and memory mappings of this file. > +It requires a file system which has been configured to support DAX. > +.PP > +DAX generally assumes all accesses are via cpu load / store instructions which > +can minimize overhead for small accesses, but may adversely affect cpu > +utilization for large transfers. > +.PP > +File I/O is done directly to/from user-space buffers and memory mapped I/O may > +be performed with direct memory mappings that bypass kernel page cache. > +.PP > +While the DAX property tends to result in data being transferred synchronously, > +it does not give the same guarantees of O_SYNC where data and the necessary > +metadata are transferred together. > +.PP > +A DAX file may support being mapped with the MAP_SYNC flag, which enables a > +program to use CPU cache flush instructions to persist CPU store operations > +without an explicit > +.BR fsync(2). > +See > +.BR mmap(2) > +for more information. > .SH RETURN VALUE > On success, zero is returned. > On error, \-1 is returned, and > -- > 2.25.1 >
