[Xen-devel] Large IO Waits for srm.

[Nicholas Lee <emptysands@xxxxxxxxx>]

I've got four VMs running including dom0, on U320 SCSI md-raid1.

In domO I'm srm (secure delete) a couple 600Mb+ files. The other domUs are idle.

Xen 2.0.6-testing/2.6.11.6

nic@sea:/backup$ vmstat 3
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa
 3  1      4   1976     32  97020    0    0   193  1811  341   512  0  6 23 71
 0  1      4   2136     32  96836    0    0     3  2507  440   650  0  1  0 99
 0  1      4   2104     32  96872    0    0     0  2571  431   664  0  0  0 100
 0  1      4   2104     32  96868    0    0     0  2561  432   668  0  0  0 100
 0  1      4   2200     32  96792    0    0    37  2379  419   656  0  0  0 100

...

nic@sea:/backup$ w
 17:26:16 up  4:21,  1 user,  load average: 1.00, 1.00, 0.92
USER     TTY      FROM              LOGIN@   IDLE   JCPU   PCPU WHAT
nic      pts/1    base-one.kiwa.co 17:22    0.00s  0.01s  0.00s w

The large IO wait level seems more than it should be. Here is an IDE
based non Xen system doing the same.

nic@lode:/home/bak$ vmstat 3
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa
 0  1  41984  57352   5856 352988    0    0     3     4    1     2  1  0 98  1
 1  1  41984  56264   5880 353000    0    0     1 24937 2584  5174  1 29  0 69
 1  0  41984  56264   5880 353020    0    0     0  6161 1417  1073  0 81  0 18
 1  0  41984  56208   5896 353052    0    0    11  1279 1106   462  0 97  0  3
 1  0  41984  56216   5904 353056    0    0     0  1256 1104   457  0 97  0  3
 1  0  41984  56216   5904 353068    0    0     0  1282 1120   457  0 97  0  3


Nicholas

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