On Fri, Jul 25, 2014 at 07:08:12PM +0100, Steven Whitehouse wrote: > Hi, > > On 25/07/14 18:52, Zach Brown wrote: > >On Fri, Jul 25, 2014 at 01:37:19PM -0400, Abhijith Das wrote: > >>Hi all, > >> > >>The topic of a readdirplus-like syscall had come up for discussion at last year's > >>LSF/MM collab summit. I wrote a couple of syscalls with their GFS2 implementations > >>to get at a directory's entries as well as stat() info on the individual inodes. > >>I'm presenting these patches and some early test results on a single-node GFS2 > >>filesystem. > >> > >>1. dirreadahead() - This patchset is very simple compared to the xgetdents() system > >>call below and scales very well for large directories in GFS2. dirreadahead() is > >>designed to be called prior to getdents+stat operations. > >Hmm. Have you tried plumbing these read-ahead calls in under the normal > >getdents() syscalls? > > > >We don't have a filereadahead() syscall and yet we somehow manage to > >implement buffered file data read-ahead :). > > > >- z > > > Well I'm not sure thats entirely true... we have readahead() and we also > have fadvise(FADV_WILLNEED) for that. Sure, fair enough. It would have been more precise to say that buffered file data readers see read-ahead without *having* to use a syscall. > doubt, but how would we tell getdents64() when we were going to read the > inodes, rather than just the file names? How does transparent file read-ahead know how far to read-ahead, if at all? How do the file systems that implement directory read-ahead today deal with this? Just playing devil's advocate here: It's not at all obvious that adding more interfaces is necessary to get directory read-ahead working, given our existing read-ahead implementations. - z -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
