Hi.
These patches add the output function for blktap statistics into xentop.
Currently, xentop outputs only blkback statistics, and not blktap statistics.
By these patches, xentop is made cover both blkback and blktap.
In xen, back-end driver has two types; blkback and blktap.
Blkback driver is old back-end driver.
Blktap driver is new back-end driver and is recommended currently.
Usage of both drivers is same, but xentop outputs only blkback statistics.
Therefore, These patches make xentop output statistics of both blkback and
blktap.
These patches include two part as follows.
1. Unification of sysfs entries' names
2. Output of statistics about blkback and blktap into xentop.
1. The name of sysfs entries are unified for VBDs.
Currently, sysfs entries' names of back-end drivers is specified "<I/O
operation type>_<unit of statistics>".
For example, in the case that a operation is "READ" and that units is the
number of requests, sysfs entries' name is "rd-req".
In addition, in the case of blktap, entries' names add prefix "tap_".
In above example, entries' name is "tap_rd_req".
The prefix is redundant.
The word "tap-" in the directory name is sufficient to distinguish VBD
types.
Therefore, it is better to remove the prefix "tap_" in sysfs entries of
blktap.
For example, currently sysfs entries are named as follows.
[root@xenmachine1 ~]# ls /sys/devices/xen-backend/vbd-1-51712/statistics/
br_req oo_req rd_req rd_sect wr_req wr_sect
[root@xenmachine1 ~]# ls /sys/devices/xen-backend/tap-2-51712/statistics/
tap_oo_req tap_rd_req tap_rd_sect tap_wr_req tap_wr_sect
After applying these patches, names of sysfs entries are changed as follows.
[root@xenmachine1 ~]# ls /sys/devices/xen-backend/vbd-1-51712/statistics/
br_req oo_req rd_req rd_sect wr_req wr_sect
[root@xenmachine1 ~]# ls /sys/devices/xen-backend/tap-2-51712/statistics/
oo_req rd_req rd_sect wr_req wr_sect
2. Xentop (and libxenstat) collects and outputs statistics of both blkback and
blktap drivers.
VBDS and VBD_xx fields mean the number of VBDs and a total statistical
amount of them, respectively.
In detail view lines, xentop outputs statistics about each VBD, namely each
thread of blkback and blktap.
In addition, in order to identify driver types, type field is added into
detail view lines.
The type field describes VBD types; "BlkBack" means usage of blkback driver
and "BlkTap" means usage of blktap driver.
For example,
xentop - 11:46:40 Xen 3.0-unstable
3 domains: 1 running, 2 blocked, 0 paused, 0 crashed, 0 dying, 0 shutdown
Mem: 1023220k total, 1022428k used, 792k free CPUs: 2 @ 2658MHz
NAME STATE CPU(sec) CPU(%) MEM(k) MEM(%) MAXMEM(k) MAXMEM(%)
VCPUS NETS NETTX(k) NETRX(k) VBDS VBD_OO VBD_RD VBD_WR SSID
Domain-0 -----r 725 3.4 729088 71.3 no limit n/a
2 4 21 22 0 0 0 0 0
FC6PVM --b--- 62 0.1 131072 12.8 131072 12.8
2 1 10 16 1 0 20537 9600 0
VBD BlkTap 51712 [ca: 0] OO: 0 RD: 20537 WR: 9600
FC6PVM2 --b--- 63 0.1 131072 12.8 131072 12.8
2 1 19 30 1 0 20490 9847 0
VBD BlkBack 51712 [ca: 0] OO: 0 RD: 20490 WR: 9847
--------------------------------------------------
Satoshi UCHIDA
NEC Corporation, Japan
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