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Diffstat (limited to 'Documentation/cgroups/unified-hierarchy.txt')
| -rw-r--r-- | Documentation/cgroups/unified-hierarchy.txt | 61 |
1 files changed, 57 insertions, 4 deletions
diff --git a/Documentation/cgroups/unified-hierarchy.txt b/Documentation/cgroups/unified-hierarchy.txt index 1ee9caf29e57..bd1ce15d5178 100644 --- a/Documentation/cgroups/unified-hierarchy.txt +++ b/Documentation/cgroups/unified-hierarchy.txt @@ -27,7 +27,7 @@ CONTENTS 5-3-1. Format 5-3-2. Control Knobs 5-4. Per-Controller Changes - 5-4-1. blkio + 5-4-1. io 5-4-2. cpuset 5-4-3. memory 6. Planned Changes @@ -203,7 +203,7 @@ other issues. The mapping from nice level to weight isn't obvious or universal, and there are various other knobs which simply aren't available for tasks. -The blkio controller implicitly creates a hidden leaf node for each +The io controller implicitly creates a hidden leaf node for each cgroup to host the tasks. The hidden leaf has its own copies of all the knobs with "leaf_" prefixed. While this allows equivalent control over internal tasks, it's with serious drawbacks. It always adds an @@ -438,9 +438,62 @@ may be specified in any order and not all pairs have to be specified. 5-4. Per-Controller Changes -5-4-1. blkio +5-4-1. io -- blk-throttle becomes properly hierarchical. +- blkio is renamed to io. The interface is overhauled anyway. The + new name is more in line with the other two major controllers, cpu + and memory, and better suited given that it may be used for cgroup + writeback without involving block layer. + +- Everything including stat is always hierarchical making separate + recursive stat files pointless and, as no internal node can have + tasks, leaf weights are meaningless. The operation model is + simplified and the interface is overhauled accordingly. + + io.stat + + The stat file. The reported stats are from the point where + bio's are issued to request_queue. The stats are counted + independent of which policies are enabled. Each line in the + file follows the following format. More fields may later be + added at the end. + + $MAJ:$MIN rbytes=$RBYTES wbytes=$WBYTES rios=$RIOS wrios=$WIOS + + io.weight + + The weight setting, currently only available and effective if + cfq-iosched is in use for the target device. The weight is + between 10 and 1000 and defaults to 500. The first line + always contains the default weight in the following format to + use when per-device setting is missing. + + default $WEIGHT + + Subsequent lines list per-device weights of the following + format. + + $MAJ:$MIN $WEIGHT + + Writing "$WEIGHT" or "default $WEIGHT" changes the default + setting. Writing "$MAJ:$MIN $WEIGHT" sets per-device weight + while "$MAJ:$MIN default" clears it. + + This file is available only on non-root cgroups. + + io.max + + The maximum bandwidth and/or iops setting, only available if + blk-throttle is enabled. The file is of the following format. + + $MAJ:$MIN rbps=$RBPS wbps=$WBPS riops=$RIOPS wiops=$WIOPS + + ${R|W}BPS are read/write bytes per second and ${R|W}IOPS are + read/write IOs per second. "max" indicates no limit. Writing + to the file follows the same format but the individual + settings may be ommitted or specified in any order. + + This file is available only on non-root cgroups. 5-4-2. cpuset |