blk-cgroup: config options re-arrangement
This patch fixes few usability and configurability issues.
o All the cgroup based controller options are configurable from
"Genral Setup/Control Group Support/" menu. blkio is the only exception.
Hence make this option visible in above menu and make it configurable from
there to bring it inline with rest of the cgroup based controllers.
o Get rid of CONFIG_DEBUG_CFQ_IOSCHED.
This option currently does two things.
- Enable printing of cgroup paths in blktrace
- Enables CONFIG_DEBUG_BLK_CGROUP, which in turn displays additional stat
files in cgroup.
If we are using group scheduling, blktrace data is of not really much use
if cgroup information is not present. To get this data, currently one has to
also enable CONFIG_DEBUG_CFQ_IOSCHED, which in turn brings the overhead of
all the additional debug stat files which is not desired.
Hence, this patch moves printing of cgroup paths under
CONFIG_CFQ_GROUP_IOSCHED.
This allows us to get rid of CONFIG_DEBUG_CFQ_IOSCHED completely. Now all
the debug stat files are controlled only by CONFIG_DEBUG_BLK_CGROUP which
can be enabled through config menu.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Divyesh Shah <dpshah@google.com>
Reviewed-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt
index d422b41..48e0b21 100644
--- a/Documentation/cgroups/blkio-controller.txt
+++ b/Documentation/cgroups/blkio-controller.txt
@@ -17,6 +17,9 @@
You can do a very simple testing of running two dd threads in two different
cgroups. Here is what you can do.
+- Enable Block IO controller
+ CONFIG_BLK_CGROUP=y
+
- Enable group scheduling in CFQ
CONFIG_CFQ_GROUP_IOSCHED=y
@@ -54,25 +57,17 @@
Various user visible config options
===================================
+CONFIG_BLK_CGROUP
+ - Block IO controller.
+
+CONFIG_DEBUG_BLK_CGROUP
+ - Debug help. Right now some additional stats file show up in cgroup
+ if this option is enabled.
+
CONFIG_CFQ_GROUP_IOSCHED
- Enables group scheduling in CFQ. Currently only 1 level of group
creation is allowed.
-CONFIG_DEBUG_CFQ_IOSCHED
- - Enables some debugging messages in blktrace. Also creates extra
- cgroup file blkio.dequeue.
-
-Config options selected automatically
-=====================================
-These config options are not user visible and are selected/deselected
-automatically based on IO scheduler configuration.
-
-CONFIG_BLK_CGROUP
- - Block IO controller. Selected by CONFIG_CFQ_GROUP_IOSCHED.
-
-CONFIG_DEBUG_BLK_CGROUP
- - Debug help. Selected by CONFIG_DEBUG_CFQ_IOSCHED.
-
Details of cgroup files
=======================
- blkio.weight
@@ -174,13 +169,13 @@
write, sync or async.
- blkio.avg_queue_size
- - Debugging aid only enabled if CONFIG_DEBUG_CFQ_IOSCHED=y.
+ - Debugging aid only enabled if CONFIG_DEBUG_BLK_CGROUP=y.
The average queue size for this cgroup over the entire time of this
cgroup's existence. Queue size samples are taken each time one of the
queues of this cgroup gets a timeslice.
- blkio.group_wait_time
- - Debugging aid only enabled if CONFIG_DEBUG_CFQ_IOSCHED=y.
+ - Debugging aid only enabled if CONFIG_DEBUG_BLK_CGROUP=y.
This is the amount of time the cgroup had to wait since it became busy
(i.e., went from 0 to 1 request queued) to get a timeslice for one of
its queues. This is different from the io_wait_time which is the
@@ -191,7 +186,7 @@
got a timeslice and will not include the current delta.
- blkio.empty_time
- - Debugging aid only enabled if CONFIG_DEBUG_CFQ_IOSCHED=y.
+ - Debugging aid only enabled if CONFIG_DEBUG_BLK_CGROUP=y.
This is the amount of time a cgroup spends without any pending
requests when not being served, i.e., it does not include any time
spent idling for one of the queues of the cgroup. This is in
@@ -200,7 +195,7 @@
time it had a pending request and will not include the current delta.
- blkio.idle_time
- - Debugging aid only enabled if CONFIG_DEBUG_CFQ_IOSCHED=y.
+ - Debugging aid only enabled if CONFIG_DEBUG_BLK_CGROUP=y.
This is the amount of time spent by the IO scheduler idling for a
given cgroup in anticipation of a better request than the exising ones
from other queues/cgroups. This is in nanoseconds. If this is read
@@ -209,7 +204,7 @@
the current delta.
- blkio.dequeue
- - Debugging aid only enabled if CONFIG_DEBUG_CFQ_IOSCHED=y. This
+ - Debugging aid only enabled if CONFIG_DEBUG_BLK_CGROUP=y. This
gives the statistics about how many a times a group was dequeued
from service tree of the device. First two fields specify the major
and minor number of the device and third field specifies the number