On Mon, Jul 11, 2016 at 04:32:58PM -0400, Jeff Layton wrote: > On Mon, 2016-07-11 at 14:04 -0400, J. Bruce Fields wrote: > > On Sun, Jul 10, 2016 at 03:55:57PM -0400, Jeff Layton wrote: > > > From: Jeff Layton <jlayton@xxxxxxxxxxxxxxx> > > > > > > v3: > > > - use sort() from lib/sort.c to sort the list > > > > > > v2: > > > - rework Tigran's patch to preserve existing selection behaviour > > > - simplify layout driver selection by sorting the list > > > > > > This is v3 of the patchset. The main change is that this patch doesn't > > > use a hand-rolled bubble sort, but rather the heapsort library in > > > lib/sort.c. This is mostly for conciseness since the array sizes are > > > generally so small that it shouldn't make any perf difference. > > > > > > Note that this does mean that we need to keep track on the number of > > > elements in the array that the server sends, so there are a few > > > ancillary changes to deal with that as well. > > > > > > Only lightly tested by mounting a server that sends both flexfiles and > > > block layouts. The client successfully selected the block layout in most > > > cases, but if I blacklist blocklayoutdriver then it selects flexfiles > > > instead. > > > > > > I'm sending these together, but I'd expect Bruce to pick up the nfsd > > > patches and Trond or Anna to pick up the client-side ones. > > > > Patches still look fine to me. Feel free to add a Reviewed-by: J. Bruce > > Fields <bfields@xxxxxxxxxx> for the client-side patches. I'll take the > > server-side patch for 4.8 assuming no objections to this approach from > > the client side. > > > > --b. > > > > Sorry, I think you added a Reviewed-by tag on the earlier set, and I > forgot to add it. I'll put it in now. BTW, these patches are in the > nfsd-4.8 branch of my tree if that makes it easier to pick them: > > https://git.samba.org/?p=jlayton/linux.git;a=shortlog;h=refs/heads/nfsd-4.8 > > I still haven't heard from Trond or Anna on the latest iteration of the > series. I think I've addressed Trond's concerns with the earlier set > though. > > The only part that I'm not sure of with the server-side patch is that > it orders the list by numerical layouttype value. In principle, it > shouldn't matter since the client should pick the best one for its > needs, but older clients will just look at the first one on the list. > > In the case where you have both SCSI and FlexFile layouts, older > clients will pick flexfiles over scsi. That may not be what we want. > Should we take more care to order the list by some measure of > "usefulness"? That would be OK with me, but I don't think it's worth a lot of effort at this point. Very few will want the current server flexfiles implementation, and they can live with just the compile-time option. Longer term this doesn't seem like something we can decide algorithmically. The suggestion I've heard is to extend the export syntax to allow "pnfs=scsi,flex" or whatever, and take the ordering as the user's priority. I agree that we want this sorted out eventually, and certainly before flexfiles becomes useful in production. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
