Re: [PATCH 3/4] xfs: make xfs_inode_set_eofblocks_tag cheaper for the common case
Dave Chinner <[email protected]>
| Newsgroups | gmane.comp.file-systems.xfs.general |
|---|---|
| Message-ID | <20160830230320.GW19025@dastard> |
On Tue, Aug 30, 2016 at 04:40:06PM +0200, Christoph Hellwig wrote: > On Fri, Aug 26, 2016 at 12:02:09PM -0400, Brian Foster wrote: > > > I don't think taking it should be too bad, but given the ops ordering > > > it also seems entirely pointless to even take it. > > > > > > > Then why are we taking it? I assumed it at least served as a memory > > barrier... > > I meant to take it for that early check, not in general. > > I guess this is another hint we should try to look into using proper > atomic bitops here.. I think we've looked at that in the past, but there were cases where we have to do things atomically with setting/clearing the flags and that required the spinlock to protect the flag modifications as well. IIRC there are also cases where we have to check/set multiple flags at once, which we cannot do with atomic bit ops. Perhaps the code has changed enough that there isn't a problem anymore, but I don't think that is the case... Cheers, Dave. -- Dave Chinner [email protected] _______________________________________________ xfs mailing list [email protected] http://oss.sgi.com/mailman/listinfo/xfs