Messages in this thread | | | Date | Mon, 15 Dec 2008 15:44:58 -0800 | From | Harry Edmon <> | Subject | Re: High load in 2.6.27, NFS / rpcauth_lookup_credcache()? |
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Trond Myklebust wrote: > On Thu, 2008-10-23 at 14:36 +0200, Max Kellermann wrote: > >> On 2008/10/22 11:12, Max Kellermann <max@duempel.org> 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?
--
Dr. Harry Edmon E-MAIL: harry@atmos.washington.edu 206-543-0547 harry@washington.edu Dept of Atmospheric Sciences FAX: 206-543-0308 University of Washington, Box 351640, Seattle, WA 98195-1640
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