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 -- 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
