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    SubjectRe: High load in 2.6.27, NFS / rpcauth_lookup_credcache()?
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    On Wed, Oct 22, 2008 at 11:12:08AM +0200, Max Kellermann wrote:
    > Hi,
    >
    > 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):

    Well, there's only 7 patches to net/sunrpc/auth.c between 2.6.25 and
    today, so worst case a 'git bisect v2.6.25..v2.6.27 net/sunrpc/auth.c'
    might not be too bad.

    No particular idea why rpcauth_lookup_credcache would be a problem,
    though.

    --b.

    >
    > 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?
    >
    > Max


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