admin-guide/cgroup-v1/blkio-controller.rst

16 level logical devices like device mapper.
21 -----------------------------
22 - Enable Block IO controller::
26 - Enable throttling in block layer::
30 - Mount blkio controller (see cgroups.txt, Why are cgroups needed?)::
32         mount -t cgroup -o blkio none /sys/fs/cgroup/blkio
34 - Specify a bandwidth rate on particular device for root group. The format
40   on device having major/minor number 8:16.
42 - Run dd to read a file and see if rate is throttled to 1MB/s or not::
83 	- Block IO controller.
86 	- Debug help. Right now some additional stats file show up in cgroup
90 	- Enable block device throttling support in block layer.
95 --------------------------------
96 - blkio.weight
97 	- Specifies per cgroup weight. This is default weight of the group
98 	  on all the devices until and unless overridden by per device rule.
102 - blkio.weight_device
103 	- One can specify per cgroup per device rules using this interface.
133 - blkio.time
134 	- disk time allocated to cgroup per device in milliseconds. First
135 	  two fields specify the major and minor number of the device and
139 - blkio.sectors
140 	- number of sectors transferred to/from disk by the group. First
141 	  two fields specify the major and minor number of the device and
143 	  group to/from the device.
145 - blkio.io_service_bytes
146 	- Number of bytes transferred to/from the disk by the group. These
147 	  are further divided by the type of operation - read or write, sync
149 	  device, third field specifies the operation type and the fourth field
152 - blkio.io_serviced
153 	- Number of IOs (bio) issued to the disk by the group. These
154 	  are further divided by the type of operation - read or write, sync
156 	  device, third field specifies the operation type and the fourth field
159 - blkio.io_service_time
160 	- Total amount of time between request dispatch and request completion
168 	  the type of operation - read or write, sync or async. First two fields
169 	  specify the major and minor number of the device, third field
173 - blkio.io_wait_time
174 	- Total amount of time the IOs for this cgroup spent waiting in the
180 	  the IO is dispatched to the device but till it actually gets serviced
181 	  (there might be a time lag here due to re-ordering of requests by the
182 	  device). This is in nanoseconds to make it meaningful for flash
183 	  devices too. This time is further divided by the type of operation -
185 	  minor number of the device, third field specifies the operation type
188 - blkio.io_merged
189 	- Total number of bios/requests merged into requests belonging to this
190 	  cgroup. This is further divided by the type of operation - read or
193 - blkio.io_queued
194 	- Total number of requests queued up at any given instant for this
195 	  cgroup. This is further divided by the type of operation - read or
198 - blkio.avg_queue_size
199 	- Debugging aid only enabled if CONFIG_BFQ_CGROUP_DEBUG=y.
204 - blkio.group_wait_time
205 	- Debugging aid only enabled if CONFIG_BFQ_CGROUP_DEBUG=y.
215 - blkio.empty_time
216 	- Debugging aid only enabled if CONFIG_BFQ_CGROUP_DEBUG=y.
224 - blkio.idle_time
225 	- Debugging aid only enabled if CONFIG_BFQ_CGROUP_DEBUG=y.
233 - blkio.dequeue
234 	- Debugging aid only enabled if CONFIG_BFQ_CGROUP_DEBUG=y. This
236 	  from service tree of the device. First two fields specify the major
237 	  and minor number of the device and third field specifies the number
238 	  of times a group was dequeued from a particular device.
240 - blkio.*_recursive
241 	- Recursive version of various stats. These files show the
242           same information as their non-recursive counterparts but
246 -----------------------------------
247 - blkio.throttle.read_bps_device
248 	- Specifies upper limit on READ rate from the device. IO rate is
249 	  specified in bytes per second. Rules are per device. Following is
254 - blkio.throttle.write_bps_device
255 	- Specifies upper limit on WRITE rate to the device. IO rate is
256 	  specified in bytes per second. Rules are per device. Following is
261 - blkio.throttle.read_iops_device
262 	- Specifies upper limit on READ rate from the device. IO rate is
263 	  specified in IO per second. Rules are per device. Following is
268 - blkio.throttle.write_iops_device
269 	- Specifies upper limit on WRITE rate to the device. IO rate is
270 	  specified in io per second. Rules are per device. Following is
275 Note: If both BW and IOPS rules are specified for a device, then IO is
278 - blkio.throttle.io_serviced
279 	- Number of IOs (bio) issued to the disk by the group. These
280 	  are further divided by the type of operation - read or write, sync
282 	  device, third field specifies the operation type and the fourth field
285 - blkio.throttle.io_service_bytes
286 	- Number of bytes transferred to/from the disk by the group. These
287 	  are further divided by the type of operation - read or write, sync
289 	  device, third field specifies the operation type and the fourth field
293 -----------------------------------
294 - blkio.reset_stats
295 	- Writing an int to this file will result in resetting all the stats