On Tue, 11 Dec 2012 11:16:33 -0500 "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote: > On Tue, Dec 11, 2012 at 11:02:28AM +1100, NeilBrown wrote: > > On Thu, 29 Nov 2012 11:30:51 +1100 NeilBrown <neilb@xxxxxxx> wrote: > > > > > On Wed, 28 Nov 2012 08:10:55 -0500 "J. Bruce Fields" <bfields@xxxxxxxxxxxx> > > > wrote: > > > > > > > On Wed, Nov 28, 2012 at 12:11:23PM +1100, Neil Brown wrote: > > > > > We have previously raised the size of the 'pollarray' once (32 -> 256) > > > > > and I have had another request to make it bigger. > > > > > Rather than changing the hard-coded value, make it depend on > > > > > RLIMIT_NOFILE. This is an upper limit on the size of the array > > > > > that can be passed to poll() anyway. > > > > > > > > Sounds like a good idea. > > > > > > > > Just out of curiosity: how does it fail? I guess mounts just start > > > > failing at some point--how do people find the workaround? > > > > > > Error seems to be > > > > > > rpcsec_gss: gss_init_sec_context: (major) Miscellaneous failure - (minor) Cannot contact any KDC for requested realm > > > > > > in rpc.gssd logs. > > > > > > I guess people could read the source to find the work around .... not ideal > > > though. I guess we should get gssd to generate some more helpful message. > > > > > > The seem to be further problems that the customer is experiencing so I might > > > wait until they are completely resolved to ensure I have complete > > > understanding before I propose a further patch. > > > > The "further problem" was that krb5 libraries use select() in a way that does > > not support file descriptors higher than 1024. This is fixed in the latest > > krb5 so that is no longer an issue. > > > > I've been thinking about your question, and about how best to deliver a fix > > to customers, and I really think it should all "just work". > > i.e. the array that gssd should be sized dynamically and RLIMIT_NOFILE should > > be increased as needed. > > Neat-o. > > > I haven't tested this, but what do people think? I don't have a problem > > changing the rlim_cur limit like this, but I wonder if it is OK to > > dynamically set rlim_max. > > What would be the concern, that we'd be depriving an admin of the > ability to set a limit? My concern in that automagically raising a so-called "hard limit" seems to be subverting the very concept of it being a "limit". > > We could instead set only the current limit and set set the max to an > admin-configurable quantity (default very large) when we start gssd. I really want to avoid any configuration. The number of fds that will be used is directly connected to the number of concurrent mounts - as there is no limit on those (I assume), I guess it is fair that there is no limit on fds used by gssd. > > But that sounds more complicated, and off hand I can't think of a reason > an admin would want to do that. OK, let's just modify the hard limit dynamically ... though I'm about to disappear for summer holidays so I doubt you'll see anything for some weeks. thanks, NeilBrown
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