On Wed, 25 Jun 2003, Nathan Ward wrote:
Several times I have mentioned this and gotten no useful response that I can remember.
I am running OpenAFS on linux machines. Take a look at the context switches
on the client and the server....
(vmstat 1, look at the "cs" column)
NFS solves this problem by having a fully kernel server and client.
Our client is fully kernel, and yet it's the client that people seem to indicate is the big problem.
One moment please...
AFS server on serv-1, client is serv-2. Gigabit ethernet between them...
[EMAIL PROTECTED]:/$ vmstat 1
procs memory swap io system cpu
r b w swpd free buff cache si so bi bo in cs us sy id
0 0 0 576 349032 37444 389620 0 0 1 2 18 11 0 0 6
0 0 0 576 282320 37512 456188 0 0 0 0 268 2707 0 24 76
0 0 0 576 282320 37512 456188 0 0 0 0 876 14909 0 43 57
0 0 0 576 282320 37512 456188 0 0 0 0 881 14884 0 40 60
0 0 0 576 282320 37512 456188 0 0 0 0 865 14917 1 44 55
0 0 0 576 282320 37512 456188 0 0 0 0 846 15008 0 39 61
1 0 0 576 254496 37596 483928 0 0 0 128 713 12035 0 44 56
0 0 2 576 238196 37612 500208 0 0 0 0 687 13162 0 43 57
0 0 2 576 238196 37612 500208 0 0 0 8 821 14754 0 43 57
0 0 1 576 238196 37612 500208 0 0 0 0 854 14737 0 39 61
0 0 1 576 238196 37612 500208 0 0 0 8 846 14696 0 45 55
0 0 0 576 238196 37612 500208 0 0 0 0 777 13821 0 34 65
0 0 0 576 238264 37612 500208 0 0 0 0 238 2982 0 6 93
0 0 0 576 238264 37612 500208 0 0 0 0 103 116 0 0 100
0 0 0 576 238264 37612 500208 0 0 0 0 103 114 0 0 100
serv-1:~# vmstat 1
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu-- --
r b swpd free buff cache si so bi bo in cs us sy id wa
0 0 4452 234396 84868 308172 0 0 1 14 10 6 0 1 99 0
0 0 4452 234388 84868 308172 0 0 0 0 120 45 0 0 100 0
0 0 4452 234388 84868 308172 0 0 0 0 125 56 0 0 100 0
0 0 4452 299904 84884 242636 0 0 0 40 114 54 0 3 97 0
1 0 4452 293592 84892 248844 0 0 0 0 2193 1944 40 12 49 0
1 0 4452 287040 84900 255388 0 0 0 0 2287 1994 45 12 44 0
1 0 4452 280476 84904 261948 0 0 0 0 2266 1838 47 12 42 0
1 0 4452 273932 84916 268476 0 0 0 0 2207 1891 41 12 47 0
1 0 4452 268280 84920 274124 0 0 0 260 2050 1724 37 14 50 0
1 0 4452 263988 84924 278412 0 0 0 0 1494 1231 28 7 64 0
1 0 4452 257436 84932 284956 0 0 0 0 2233 2050 47 9 44 0
2 0 4452 250884 84940 291500 0 0 0 0 2260 1823 48 10 42 0
1 0 4452 244320 84944 298060 0 0 0 0 2251 1922 43 14 43 0
1 0 4452 238168 84952 304204 0 0 0 168 2132 1857 41 10 49 0
0 0 4452 234196 84956 308172 0 0 0 0 1361 1150 25 8 66 0
0 0 4452 234196 84956 308172 0 0 0 0 127 60 0 0 100 0
[EMAIL PROTECTED]:/$ dd if=/dev/zero of=/afs/alb-nz/public/blah bs=256k count=256 256+0 records in
256+0 records out
With a client machine with 100Mbit ethernet, the context switches are roughly halfed, with the speed being roughly halved also.
I am using a disk based cache for these machines. I'll try again with a ramdisk and report back.
People claim that "OpenAFS scales better", sure it definately does, but
should this mean that it's maximum speed is degraded? I don't see how this
can be..?
I don't think it should, or that it does. I think it's incidental.
Right, my point here is that people use it as an excuse, as though its slow because its scalable.
-- Nathan Ward Esphion Ltd.
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