On Mon, 2008-12-15 at 15:44 -0800, Harry Edmon wrote: > Trond Myklebust wrote: > > On Thu, 2008-10-23 at 14:36 +0200, Max Kellermann wrote: > > > >> On 2008/10/22 11:12, Max Kellermann <max@xxxxxxxxxxx> wrote: > >> > >>> after I was able to fix http://lkml.org/lkml/2008/10/17/147, the > >>> server which was already upgraded to 2.6.27.2 still gets very high > >>> load. It is a web server with NFS file storage (NetApp), and while > >>> the others in the cluster (kernel 2.6.25) have a load of 1-3, 2.6.27.2 > >>> gets 30-50. > >>> > >>> I did an oprofile, with the following results (server just started, > >>> load "only" 5-10): > >>> > >>> 87593 56.1116 (no location information) vmlinux > >>> vmlinux rpcauth_lookup_credcache > >>> 16037 10.2732 auth_generic.c:0 vmlinux > >>> vmlinux generic_match > >>> 6460 4.1382 (no location information) php4 > >>> php4 (no symbols) > >>> 2478 1.5874 (no location information) libc-2.7.so > >>> libc-2.7.so (no symbols) > >>> [...] > >>> > >>> We havn't configured any special authentication method. It is a NFSv3 > >>> over UDP mount, but the kernel has NFSv4 and therefore KRB5 enabled. > >>> > >>> Any ideas why rpcauth_lookup_credcache() goes overboard with CPU > >>> usage? > >>> > >> I have bisected the problem: 98a8e323 is the result ("SUNRPC: Add a > >> helper rpcauth_lookup_generic_cred()"). 5c691044 is ok. > >> > >> See the attached oprofile annotation data for both commits. I guess > >> that the function rpcauth_lookup_credcache() is waiting for a spinlock > >> too often and too long. Trond, any idea? > >> > > > > Can you add a '-v' to the rpc.gssd daemon startup line? I'd like to see > > how often you are creating new gss contexts. > > > > > >> Harry: added you to Cc because your problem sounds similar. > >> > > > > Harry's problem is should be unrelated. afaik, he is seeing a problem > > with userland RPC code, not kernel rpc code. > > > > Trond > > > > > I am finally getting some time to look at my problem that I originally > reported in October (SUNRPC problem with 2.6.26 and beyond), and I am > seeing the same behavior as Max Kellermann when my machine slows as I > described earlier. The system in question is currently running > 2.6.27.7. Here is what I see when it is misbehaving: > > samples % image name app name > symbol name > 11380517 57.4191 sunrpc.ko sunrpc > rpcauth_lookup_credcache > 3263657 16.4664 sunrpc.ko sunrpc > generic_match > 1081287 5.4555 vmlinux vmlinux > copy_user_generic_string > 499407 2.5197 vmlinux vmlinux > __posix_lock_file > [...] > > And here is what I see when I stop the programs that are chewing up all > the system time, and then starting them up again: > > samples % image name app name > symbol name > 6372650 21.7978 vmlinux vmlinux > copy_user_generic_string > 5401386 18.4755 sunrpc.ko sunrpc > rpcauth_lookup_credcache > 3018753 10.3257 vmlinux vmlinux > __posix_lock_file > 1050095 3.5919 sunrpc.ko sunrpc > generic_match > > > and I am not using Kerberos with NFSv4 (i.e. no rpc.gssd). Did you ever > find a solution for this problem with rpcauth_lookup_credcache? http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git&a=commitdiff&h=23918b03060f6e572168fdde1798a905679d2e06 Trond -- 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
