• Chuck Lever's avatar
    sunrpc: Disable splice for krb5i · 06eb8a56
    Chuck Lever authored
    Running a multi-threaded 8KB fio test (70/30 mix), three or four out
    of twelve of the jobs fail when using krb5i. The failure is an EIO
    on a read.
    
    Troubleshooting confirmed the EIO results when the client fails to
    verify the MIC of an NFS READ reply. Bruce suggested the problem
    could be due to the data payload changing between the time the
    reply's MIC was computed on the server and the time the reply was
    actually sent.
    
    krb5p gets around this problem by disabling RQ_SPLICE_OK. Use the
    same mechanism for krb5i RPCs.
    
    "iozone -i0 -i1 -s128m -y1k -az -I", export is tmpfs, mount is
    sec=krb5i,vers=3,proto=rdma. The important numbers are the
    read / reread column.
    
    Here's without the RQ_SPLICE_OK patch:
    
                  kB  reclen    write  rewrite    read    reread
              131072       1     7546     7929     8396     8267
              131072       2    14375    14600    15843    15639
              131072       4    19280    19248    21303    21410
              131072       8    32350    31772    35199    34883
              131072      16    36748    37477    49365    51706
              131072      32    55669    56059    57475    57389
              131072      64    74599    75190    74903    75550
              131072     128    99810   101446   102828   102724
              131072     256   122042   122612   124806   125026
              131072     512   137614   138004   141412   141267
              131072    1024   146601   148774   151356   151409
              131072    2048   180684   181727   293140   292840
              131072    4096   206907   207658   552964   549029
              131072    8192   223982   224360   454493   473469
              131072   16384   228927   228390   654734   632607
    
    And here's with it:
    
                  kB  reclen    write  rewrite    read    reread
              131072       1     7700     7365     7958     8011
              131072       2    13211    13303    14937    14414
              131072       4    19001    19265    20544    20657
              131072       8    30883    31097    34255    33566
              131072      16    36868    34908    51499    49944
              131072      32    56428    55535    58710    56952
              131072      64    73507    74676    75619    74378
              131072     128   100324   101442   103276   102736
              131072     256   122517   122995   124639   124150
              131072     512   137317   139007   140530   140830
              131072    1024   146807   148923   151246   151072
              131072    2048   179656   180732   292631   292034
              131072    4096   206216   208583   543355   541951
              131072    8192   223738   224273   494201   489372
              131072   16384   229313   229840   691719   668427
    
    I would say that there is not much difference in this test.
    
    For good measure, here's the same test with sec=krb5p:
    
                  kB  reclen    write  rewrite    read    reread
              131072       1     5982     5881     6137     6218
              131072       2    10216    10252    10850    10932
              131072       4    12236    12575    15375    15526
              131072       8    15461    15462    23821    22351
              131072      16    25677    25811    27529    27640
              131072      32    31903    32354    34063    33857
              131072      64    42989    43188    45635    45561
              131072     128    52848    53210    56144    56141
              131072     256    59123    59214    62691    62933
              131072     512    63140    63277    66887    67025
              131072    1024    65255    65299    69213    69140
              131072    2048    76454    76555   133767   133862
              131072    4096    84726    84883   251925   250702
              131072    8192    89491    89482   270821   276085
              131072   16384    91572    91597   361768   336868
    
    BugLink: https://bugzilla.linux-nfs.org/show_bug.cgi?id=307Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
    Reviewed-by: default avatarJeff Layton <jlayton@redhat.com>
    Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
    06eb8a56
svcauth_gss.c 46.2 KB