On Thu, Aug 23, 2012 at 08:23:18AM -0400, J. Bruce Fields wrote: > On Thu, Aug 23, 2012 at 02:43:23PM +0400, Cyrill Gorcunov wrote: > > Hi guys, > > > > here is updated version of the fdinfo via procfs series, > > the changes from previous one are the following > > > > - fhandle is carried inside inotify mark but this feature > > is CONFIG dependent to not bloat the kernel for users > > who don't need it > > As Al points out, this doesn't help much: if this feature is something a > distro will want to provide, then in practice all their users are > eventually going to end up with it turned on. > Yes, I remember what Al has said, the problem is that this data attached to inotify mark is not just a couple of bytes but rather about 136 bytes per mark, and encoding this fhandle will take some cycles on mark creation as well. Thus when in a sake of c/r we simply have no other way and are to pay some trade off cost for c/r functionality, i don't think the regular users (and note that CONFIG_CHECKPOINT_RESTORE is off by default) should pay same cost for nothing. That's why I made it config dependant. Again if you still think that making it config-option is a bad idea I'll rip this symbols off, it's not a problem. > Could you quantify the cost somehow? > About 136 bytes per inotify mark. > I wonder if you could get away with something less than MAX_HANDLE_SIZE? > 128 bytes is the maximum allowable by NFSv4. In practice I don't think > any of our filesystems need more than 40 or so right now. Look, Bruce, I would like to follow the limits we have #define'd in kernel, because it makes code easier to support. I can #define some limit for inotify fhandle but what should I print in fdinfo if say there is no space left in buffer? Cyrill -- 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
