Hi Jason, On Fri, Jul 26, 2013 at 05:11:55PM -0400, Jason Rosenberg wrote: > Is it safe to say that speculative preallocation will not be used if a file > is opened read-only? The blocks will only be reserved on an appending write. > It turns out that the kafka server does indeed write lots of log files, and > rotate them after they reach a max size, but never closes the files until > the app exits, or until it deletes the files. This is because it needs to > make them available for reading, etc. So, an obvious change for kafka > might be to close each log file after rotating, and then re-open it > read-only for consumers of the data. Does that sound like a solution that > would pro-actively release pre-allocated storage? An interesting idea, and I'm not quite sure. The blocks past EOF are freed in xfs_release on close in some circumstances, and it looks like you have a chance to call xfs_free_eofblocks (at least in the most uptodate codebase) if you did not use explicit preallocation (e.g. fallocate or an xfs ioctl) and did not open it append-only. You could reopen with read-write flags and it wouldn't make a difference vs read-only, so long as you don't do an appending write. Seems like it's worth a try. Another possibility is to look into what would happen if you do a truncate up to i_size when you're ready to stop appending to the file. I haven't checked that out though. Regards, Ben _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
