diff options
author | Greg Kroah-Hartman | 2019-06-17 11:23:24 +0200 |
---|---|---|
committer | Greg Kroah-Hartman | 2019-06-17 11:23:24 +0200 |
commit | a954e5fb4bc2d401b8fc3b4c7cd316497ff80225 (patch) | |
tree | 06af23b232c7c2e795a2fef8a5a0604ec64d5092 /Documentation | |
parent | e137d34f94ebcb6508d7c8614ac045583fffbe2a (diff) | |
parent | 9e0babf2c06c73cda2c0cd37a1653d823adb40ec (diff) |
Merge 5.2-rc5 into usb-next
We need the USB fixes in here as well.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/arm64/sve.txt | 16 | ||||
-rw-r--r-- | Documentation/block/switching-sched.txt | 18 | ||||
-rw-r--r-- | Documentation/cgroup-v1/blkio-controller.txt | 96 | ||||
-rw-r--r-- | Documentation/cgroup-v1/hugetlb.txt | 22 | ||||
-rw-r--r-- | Documentation/filesystems/overlayfs.txt | 16 |
5 files changed, 58 insertions, 110 deletions
diff --git a/Documentation/arm64/sve.txt b/Documentation/arm64/sve.txt index 9940e924a47e..5689fc9a976a 100644 --- a/Documentation/arm64/sve.txt +++ b/Documentation/arm64/sve.txt @@ -56,6 +56,18 @@ model features for SVE is included in Appendix A. is to connect to a target process first and then attempt a ptrace(PTRACE_GETREGSET, pid, NT_ARM_SVE, &iov). +* Whenever SVE scalable register values (Zn, Pn, FFR) are exchanged in memory + between userspace and the kernel, the register value is encoded in memory in + an endianness-invariant layout, with bits [(8 * i + 7) : (8 * i)] encoded at + byte offset i from the start of the memory representation. This affects for + example the signal frame (struct sve_context) and ptrace interface + (struct user_sve_header) and associated data. + + Beware that on big-endian systems this results in a different byte order than + for the FPSIMD V-registers, which are stored as single host-endian 128-bit + values, with bits [(127 - 8 * i) : (120 - 8 * i)] of the register encoded at + byte offset i. (struct fpsimd_context, struct user_fpsimd_state). + 2. Vector length terminology ----------------------------- @@ -124,6 +136,10 @@ the SVE instruction set architecture. size and layout. Macros SVE_SIG_* are defined [1] to facilitate access to the members. +* Each scalable register (Zn, Pn, FFR) is stored in an endianness-invariant + layout, with bits [(8 * i + 7) : (8 * i)] stored at byte offset i from the + start of the register's representation in memory. + * If the SVE context is too big to fit in sigcontext.__reserved[], then extra space is allocated on the stack, an extra_context record is written in __reserved[] referencing this space. sve_context is then written in the diff --git a/Documentation/block/switching-sched.txt b/Documentation/block/switching-sched.txt index 3b2612e342f1..7977f6fb8b20 100644 --- a/Documentation/block/switching-sched.txt +++ b/Documentation/block/switching-sched.txt @@ -13,11 +13,9 @@ you can do so by typing: # mount none /sys -t sysfs -As of the Linux 2.6.10 kernel, it is now possible to change the -IO scheduler for a given block device on the fly (thus making it possible, -for instance, to set the CFQ scheduler for the system default, but -set a specific device to use the deadline or noop schedulers - which -can improve that device's throughput). +It is possible to change the IO scheduler for a given block device on +the fly to select one of mq-deadline, none, bfq, or kyber schedulers - +which can improve that device's throughput. To set a specific scheduler, simply do this: @@ -30,8 +28,8 @@ The list of defined schedulers can be found by simply doing a "cat /sys/block/DEV/queue/scheduler" - the list of valid names will be displayed, with the currently selected scheduler in brackets: -# cat /sys/block/hda/queue/scheduler -noop deadline [cfq] -# echo deadline > /sys/block/hda/queue/scheduler -# cat /sys/block/hda/queue/scheduler -noop [deadline] cfq +# cat /sys/block/sda/queue/scheduler +[mq-deadline] kyber bfq none +# echo none >/sys/block/sda/queue/scheduler +# cat /sys/block/sda/queue/scheduler +[none] mq-deadline kyber bfq diff --git a/Documentation/cgroup-v1/blkio-controller.txt b/Documentation/cgroup-v1/blkio-controller.txt index 673dc34d3f78..d1a1b7bdd03a 100644 --- a/Documentation/cgroup-v1/blkio-controller.txt +++ b/Documentation/cgroup-v1/blkio-controller.txt @@ -8,61 +8,13 @@ both at leaf nodes as well as at intermediate nodes in a storage hierarchy. Plan is to use the same cgroup based management interface for blkio controller and based on user options switch IO policies in the background. -Currently two IO control policies are implemented. First one is proportional -weight time based division of disk policy. It is implemented in CFQ. Hence -this policy takes effect only on leaf nodes when CFQ is being used. The second -one is throttling policy which can be used to specify upper IO rate limits -on devices. This policy is implemented in generic block layer and can be -used on leaf nodes as well as higher level logical devices like device mapper. +One IO control policy is throttling policy which can be used to +specify upper IO rate limits on devices. This policy is implemented in +generic block layer and can be used on leaf nodes as well as higher +level logical devices like device mapper. HOWTO ===== -Proportional Weight division of bandwidth ------------------------------------------ -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 - -- Compile and boot into kernel and mount IO controller (blkio); see - cgroups.txt, Why are cgroups needed?. - - mount -t tmpfs cgroup_root /sys/fs/cgroup - mkdir /sys/fs/cgroup/blkio - mount -t cgroup -o blkio none /sys/fs/cgroup/blkio - -- Create two cgroups - mkdir -p /sys/fs/cgroup/blkio/test1/ /sys/fs/cgroup/blkio/test2 - -- Set weights of group test1 and test2 - echo 1000 > /sys/fs/cgroup/blkio/test1/blkio.weight - echo 500 > /sys/fs/cgroup/blkio/test2/blkio.weight - -- Create two same size files (say 512MB each) on same disk (file1, file2) and - launch two dd threads in different cgroup to read those files. - - sync - echo 3 > /proc/sys/vm/drop_caches - - dd if=/mnt/sdb/zerofile1 of=/dev/null & - echo $! > /sys/fs/cgroup/blkio/test1/tasks - cat /sys/fs/cgroup/blkio/test1/tasks - - dd if=/mnt/sdb/zerofile2 of=/dev/null & - echo $! > /sys/fs/cgroup/blkio/test2/tasks - cat /sys/fs/cgroup/blkio/test2/tasks - -- At macro level, first dd should finish first. To get more precise data, keep - on looking at (with the help of script), at blkio.disk_time and - blkio.disk_sectors files of both test1 and test2 groups. This will tell how - much disk time (in milliseconds), each group got and how many sectors each - group dispatched to the disk. We provide fairness in terms of disk time, so - ideally io.disk_time of cgroups should be in proportion to the weight. - Throttling/Upper Limit policy ----------------------------- - Enable Block IO controller @@ -94,7 +46,7 @@ Throttling/Upper Limit policy Hierarchical Cgroups ==================== -Both CFQ and throttling implement hierarchy support; however, +Throttling implements hierarchy support; however, throttling's hierarchy support is enabled iff "sane_behavior" is enabled from cgroup side, which currently is a development option and not publicly available. @@ -107,9 +59,8 @@ If somebody created a hierarchy like as follows. | test3 -CFQ by default and throttling with "sane_behavior" will handle the -hierarchy correctly. For details on CFQ hierarchy support, refer to -Documentation/block/cfq-iosched.txt. For throttling, all limits apply +Throttling with "sane_behavior" will handle the +hierarchy correctly. For throttling, all limits apply to the whole subtree while all statistics are local to the IOs directly generated by tasks in that cgroup. @@ -130,10 +81,6 @@ 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_BLK_DEV_THROTTLING - Enable block device throttling support in block layer. @@ -344,32 +291,3 @@ Common files among various policies - blkio.reset_stats - Writing an int to this file will result in resetting all the stats for that cgroup. - -CFQ sysfs tunable -================= -/sys/block/<disk>/queue/iosched/slice_idle ------------------------------------------- -On a faster hardware CFQ can be slow, especially with sequential workload. -This happens because CFQ idles on a single queue and single queue might not -drive deeper request queue depths to keep the storage busy. In such scenarios -one can try setting slice_idle=0 and that would switch CFQ to IOPS -(IO operations per second) mode on NCQ supporting hardware. - -That means CFQ will not idle between cfq queues of a cfq group and hence be -able to driver higher queue depth and achieve better throughput. That also -means that cfq provides fairness among groups in terms of IOPS and not in -terms of disk time. - -/sys/block/<disk>/queue/iosched/group_idle ------------------------------------------- -If one disables idling on individual cfq queues and cfq service trees by -setting slice_idle=0, group_idle kicks in. That means CFQ will still idle -on the group in an attempt to provide fairness among groups. - -By default group_idle is same as slice_idle and does not do anything if -slice_idle is enabled. - -One can experience an overall throughput drop if you have created multiple -groups and put applications in that group which are not driving enough -IO to keep disk busy. In that case set group_idle=0, and CFQ will not idle -on individual groups and throughput should improve. diff --git a/Documentation/cgroup-v1/hugetlb.txt b/Documentation/cgroup-v1/hugetlb.txt index 106245c3aecc..1260e5369b9b 100644 --- a/Documentation/cgroup-v1/hugetlb.txt +++ b/Documentation/cgroup-v1/hugetlb.txt @@ -32,14 +32,18 @@ Brief summary of control files hugetlb.<hugepagesize>.usage_in_bytes # show current usage for "hugepagesize" hugetlb hugetlb.<hugepagesize>.failcnt # show the number of allocation failure due to HugeTLB limit -For a system supporting two hugepage size (16M and 16G) the control +For a system supporting three hugepage sizes (64k, 32M and 1G), the control files include: -hugetlb.16GB.limit_in_bytes -hugetlb.16GB.max_usage_in_bytes -hugetlb.16GB.usage_in_bytes -hugetlb.16GB.failcnt -hugetlb.16MB.limit_in_bytes -hugetlb.16MB.max_usage_in_bytes -hugetlb.16MB.usage_in_bytes -hugetlb.16MB.failcnt +hugetlb.1GB.limit_in_bytes +hugetlb.1GB.max_usage_in_bytes +hugetlb.1GB.usage_in_bytes +hugetlb.1GB.failcnt +hugetlb.64KB.limit_in_bytes +hugetlb.64KB.max_usage_in_bytes +hugetlb.64KB.usage_in_bytes +hugetlb.64KB.failcnt +hugetlb.32MB.limit_in_bytes +hugetlb.32MB.max_usage_in_bytes +hugetlb.32MB.usage_in_bytes +hugetlb.32MB.failcnt diff --git a/Documentation/filesystems/overlayfs.txt b/Documentation/filesystems/overlayfs.txt index eef7d9d259e8..1da2f1668f08 100644 --- a/Documentation/filesystems/overlayfs.txt +++ b/Documentation/filesystems/overlayfs.txt @@ -336,8 +336,20 @@ the copied layers will fail the verification of the lower root file handle. Non-standard behavior --------------------- -Overlayfs can now act as a POSIX compliant filesystem with the following -features turned on: +Current version of overlayfs can act as a mostly POSIX compliant +filesystem. + +This is the list of cases that overlayfs doesn't currently handle: + +a) POSIX mandates updating st_atime for reads. This is currently not +done in the case when the file resides on a lower layer. + +b) If a file residing on a lower layer is opened for read-only and then +memory mapped with MAP_SHARED, then subsequent changes to the file are not +reflected in the memory mapping. + +The following options allow overlayfs to act more like a standards +compliant filesystem: 1) "redirect_dir" |