On Nov 11, 2013, at 14:05, Steve Dickson <SteveD@xxxxxxxxxx> wrote: > > > On 11/11/13 13:53, Myklebust, Trond wrote: >> >> On Nov 11, 2013, at 13:43, Steve Dickson <SteveD@xxxxxxxxxx> wrote: >> >>> >>> >>> On 11/11/13 13:25, Myklebust, Trond wrote: >>>> >>>> On Nov 11, 2013, at 13:06, Steve Dickson <SteveD@xxxxxxxxxx> wrote: >>>> >>>>> >>>>> >>>>> On 09/11/13 18:12, Myklebust, Trond wrote: >>>>>> One alternative to the above scheme, which I believe that I’ve >>>>>> suggested before, is to have a permanent entry in rpc_pipefs >>>>>> that rpc.gssd can open and that the kernel can use to detect >>>>>> that it is running. If we make it /var/lib/nfs/rpc_pipefs/gssd/clnt00/gssd, >>>>>> then AFAICS we don’t need to change nfs-utils at all, since all newer >>>>>> versions of rpc.gssd will try to open for read anything of the form >>>>>> /var/lib/nfs/rpc_pipefs/*/clntXX/gssd... >>>>> >>>>> After further review I am going going have to disagree with you on this. >>>>> Since all the context is cached on the initial mount the kernel >>>> >>>> What context? >>> The krb5 blob that the kernel is call up to rpc.gssd to get.. Maybe >>> I'm using the wrong terminology??? >> >> That’s only the machine cred. User credentials get allocated and freed all the time. >> >> When the server reboots, then all GSS contexts need to be re-established, >> which can be a lot of call_usermodehelper() upcalls; that’s one of the >> reasons why we decided in favour of a gssd daemon in the first place. > Just curious... Why is the call_usermodehelper() upcalls more expensive > than the rpc_pipefs upcalls? Each upcall requires you to allocate a complete new process context and run another instance of the gssd executable. If you have enough users, then a reboot situation can quickly escalate into chewing up significantly greater amounts of memory than the single daemon does. -- 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
