diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/cgroups/memory.txt | 16 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/media/coda.txt | 30 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/misc/sram.txt | 16 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/rtc/atmel,at91rm9200-rtc.txt | 15 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/video/simple-framebuffer.txt | 25 | ||||
| -rw-r--r-- | Documentation/filesystems/vfat.txt | 26 | ||||
| -rw-r--r-- | Documentation/sysctl/vm.txt | 83 | ||||
| -rw-r--r-- | Documentation/vm/overcommit-accounting | 8 |
8 files changed, 207 insertions, 12 deletions
diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt index 17b91e012de0..3aaa984856f1 100644 --- a/Documentation/cgroups/memory.txt +++ b/Documentation/cgroups/memory.txt @@ -70,6 +70,7 @@ Brief summary of control files. memory.move_charge_at_immigrate # set/show controls of moving charges memory.oom_control # set/show oom controls. memory.numa_stat # show the number of memory usage per numa node + memory.dangling_memcgs # show debugging information about dangling groups memory.kmem.limit_in_bytes # set/show hard limit for kernel memory memory.kmem.usage_in_bytes # show current kernel memory allocation @@ -577,6 +578,21 @@ unevictable=<total anon pages> N0=<node 0 pages> N1=<node 1 pages> ... And we have total = file + anon + unevictable. +5.7 dangling_memcgs + +This file will only be ever present in the root cgroup, if the option +CONFIG_MEMCG_DEBUG_ASYNC_DESTROY is set. When a memcg is destroyed, the memory +consumed by it may not be immediately freed. This is because when some +extensions are used, such as swap or kernel memory, objects can outlive the +group and hold a reference to it. + +If this is the case, the dangling_memcgs file will show information about what +are the memcgs still alive, and which references are still preventing it to be +freed. There is nothing wrong with that, but it is very useful when debugging, +to know where this memory is being held. This is a developer-oriented debugging +facility only, and no guarantees of interface stability will be given. The file +is read-only, and has the sole purpose of displaying information. + 6. Hierarchy support The memory controller supports a deep hierarchy and hierarchical accounting. diff --git a/Documentation/devicetree/bindings/media/coda.txt b/Documentation/devicetree/bindings/media/coda.txt new file mode 100644 index 000000000000..2865d04e4030 --- /dev/null +++ b/Documentation/devicetree/bindings/media/coda.txt @@ -0,0 +1,30 @@ +Chips&Media Coda multi-standard codec IP +======================================== + +Coda codec IPs are present in i.MX SoCs in various versions, +called VPU (Video Processing Unit). + +Required properties: +- compatible : should be "fsl,<chip>-src" for i.MX SoCs: + (a) "fsl,imx27-vpu" for CodaDx6 present in i.MX27 + (b) "fsl,imx53-vpu" for CODA7541 present in i.MX53 + (c) "fsl,imx6q-vpu" for CODA960 present in i.MX6q +- reg: should be register base and length as documented in the + SoC reference manual +- interrupts : Should contain the VPU interrupt. For CODA960, + a second interrupt is needed for the MJPEG unit. +- clocks : Should contain the ahb and per clocks, in the order + determined by the clock-names property. +- clock-names : Should be "ahb", "per" +- iram : phandle pointing to the SRAM device node + +Example: + +vpu: vpu@63ff4000 { + compatible = "fsl,imx53-vpu"; + reg = <0x63ff4000 0x1000>; + interrupts = <9>; + clocks = <&clks 63>, <&clks 63>; + clock-names = "ahb", "per"; + iram = <&ocram>; +}; diff --git a/Documentation/devicetree/bindings/misc/sram.txt b/Documentation/devicetree/bindings/misc/sram.txt new file mode 100644 index 000000000000..4d0a00e453a8 --- /dev/null +++ b/Documentation/devicetree/bindings/misc/sram.txt @@ -0,0 +1,16 @@ +Generic on-chip SRAM + +Simple IO memory regions to be managed by the genalloc API. + +Required properties: + +- compatible : mmio-sram + +- reg : SRAM iomem address range + +Example: + +sram: sram@5c000000 { + compatible = "mmio-sram"; + reg = <0x5c000000 0x40000>; /* 256 KiB SRAM at address 0x5c000000 */ +}; diff --git a/Documentation/devicetree/bindings/rtc/atmel,at91rm9200-rtc.txt b/Documentation/devicetree/bindings/rtc/atmel,at91rm9200-rtc.txt new file mode 100644 index 000000000000..2a3feabd3b22 --- /dev/null +++ b/Documentation/devicetree/bindings/rtc/atmel,at91rm9200-rtc.txt @@ -0,0 +1,15 @@ +Atmel AT91RM9200 Real Time Clock + +Required properties: +- compatible: should be: "atmel,at91rm9200-rtc" +- reg: physical base address of the controller and length of memory mapped + region. +- interrupts: rtc alarm/event interrupt + +Example: + +rtc@fffffe00 { + compatible = "atmel,at91rm9200-rtc"; + reg = <0xfffffe00 0x100>; + interrupts = <1 4 7>; +}; diff --git a/Documentation/devicetree/bindings/video/simple-framebuffer.txt b/Documentation/devicetree/bindings/video/simple-framebuffer.txt new file mode 100644 index 000000000000..3ea460583111 --- /dev/null +++ b/Documentation/devicetree/bindings/video/simple-framebuffer.txt @@ -0,0 +1,25 @@ +Simple Framebuffer + +A simple frame-buffer describes a raw memory region that may be rendered to, +with the assumption that the display hardware has already been set up to scan +out from that buffer. + +Required properties: +- compatible: "simple-framebuffer" +- reg: Should contain the location and size of the framebuffer memory. +- width: The width of the framebuffer in pixels. +- height: The height of the framebuffer in pixels. +- stride: The number of bytes in each line of the framebuffer. +- format: The format of the framebuffer surface. Valid values are: + - r5g6b5 (16-bit pixels, d[15:11]=r, d[10:5]=g, d[4:0]=b). + +Example: + + framebuffer { + compatible = "simple-framebuffer"; + reg = <0x1d385000 (1600 * 1200 * 2)>; + width = <1600>; + height = <1200>; + stride = <(1600 * 2)>; + format = "r5g6b5"; + }; diff --git a/Documentation/filesystems/vfat.txt b/Documentation/filesystems/vfat.txt index d230dd9c99b0..4a93e98b290a 100644 --- a/Documentation/filesystems/vfat.txt +++ b/Documentation/filesystems/vfat.txt @@ -150,12 +150,28 @@ discard -- If set, issues discard/TRIM commands to the block device when blocks are freed. This is useful for SSD devices and sparse/thinly-provisoned LUNs. -nfs -- This option maintains an index (cache) of directory - inodes by i_logstart which is used by the nfs-related code to - improve look-ups. +nfs=stale_rw|nostale_ro + Enable this only if you want to export the FAT filesystem + over NFS. + + stale_rw: This option maintains an index (cache) of directory + inodes by i_logstart which is used by the nfs-related code to + improve look-ups. Full file operations (read/write) over NFS is + supported but with cache eviction at NFS server, this could + result in ESTALE issues. + + nostale_ro: This option bases the inode number and filehandle + on the on-disk location of a file in the MS-DOS directory entry. + This ensures that ESTALE will not be returned after a file is + evicted from the inode cache. However, it means that operations + such as rename, create and unlink could cause filehandles that + previously pointed at one file to point at a different file, + potentially causing data corruption. For this reason, this + option also mounts the filesystem readonly. + + To maintain backward compatibility, '-o nfs' is also accepted, + defaulting to stale_rw - Enable this only if you want to export the FAT filesystem - over NFS <bool>: 0,1,yes,no,true,false diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index 078701fdbd4d..a5717c38834a 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -18,6 +18,7 @@ files can be found in mm/swap.c. Currently, these files are in /proc/sys/vm: +- admin_reserve_kbytes - block_dump - compact_memory - dirty_background_bytes @@ -53,11 +54,41 @@ Currently, these files are in /proc/sys/vm: - percpu_pagelist_fraction - stat_interval - swappiness +- user_reserve_kbytes - vfs_cache_pressure - zone_reclaim_mode ============================================================== +admin_reserve_kbytes + +The amount of free memory in the system that should be reserved for users +with the capability cap_sys_admin. + +admin_reserve_kbytes defaults to min(3% of free pages, 8MB) + +That should provide enough for the admin to log in and kill a process, +if necessary, under the default overcommit 'guess' mode. + +Systems running under overcommit 'never' should increase this to account +for the full Virtual Memory Size of programs used to recover. Otherwise, +root may not be able to log in to recover the system. + +How do you calculate a minimum useful reserve? + +sshd or login + bash (or some other shell) + top (or ps, kill, etc.) + +For overcommit 'guess', we can sum resident set sizes (RSS). +On x86_64 this is about 8MB. + +For overcommit 'never', we can take the max of their virtual sizes (VSZ) +and add the sum of their RSS. +On x86_64 this is about 128MB. + +Changing this takes effect whenever an application requests memory. + +============================================================== + block_dump block_dump enables block I/O debugging when set to a nonzero value. More @@ -138,18 +169,39 @@ Setting this to zero disables periodic writeback altogether. drop_caches -Writing to this will cause the kernel to drop clean caches, dentries and -inodes from memory, causing that memory to become free. +Writing to this will cause the kernel to drop clean caches, as well as +reclaimable slab objects like dentries and inodes. Once dropped, their +memory becomes free. To free pagecache: echo 1 > /proc/sys/vm/drop_caches -To free dentries and inodes: +To free reclaimable slab objects (includes dentries and inodes): echo 2 > /proc/sys/vm/drop_caches -To free pagecache, dentries and inodes: +To free slab objects and pagecache: echo 3 > /proc/sys/vm/drop_caches -As this is a non-destructive operation and dirty objects are not freeable, the -user should run `sync' first. +This is a non-destructive operation and will not free any dirty objects. +To increase the number of objects freed by this operation, the user may run +`sync' prior to writing to /proc/sys/vm/drop_caches. This will minimize the +number of dirty objects on the system and create more candidates to be +dropped. + +This file is not a means to control the growth of the various kernel caches +(inodes, dentries, pagecache, etc...) These objects are automatically +reclaimed by the kernel when memory is needed elsewhere on the system. + +Use of this file can cause performance problems. Since it discards cached +objects, it may cost a significant amount of I/O and CPU to recreate the +dropped objects, especially if they were under heavy use. Because of this, +use outside of a testing or debugging environment is not recommended. + +You may see informational messages in your kernel log when this file is +used: + + cat (1234): dropped kernel caches: 3 + +These are informational only. They do not mean that anything is wrong +with your system. ============================================================== @@ -542,6 +594,7 @@ memory until it actually runs out. When this flag is 2, the kernel uses a "never overcommit" policy that attempts to prevent any overcommit of memory. +Note that user_reserve_kbytes affects this policy. This feature can be very useful because there are a lot of programs that malloc() huge amounts of memory "just-in-case" @@ -645,6 +698,24 @@ The default value is 60. ============================================================== +- user_reserve_kbytes + +When overcommit_memory is set to 2, "never overommit" mode, reserve +min(3% of current process size, user_reserve_kbytes) of free memory. +This is intended to prevent a user from starting a single memory hogging +process, such that they cannot recover (kill the hog). + +user_reserve_kbytes defaults to min(3% of the current process size, 128MB). + +If this is reduced to zero, then the user will be allowed to allocate +all free memory with a single process, minus admin_reserve_kbytes. +Any subsequent attempts to execute a command will result in +"fork: Cannot allocate memory". + +Changing this takes effect whenever an application requests memory. + +============================================================== + vfs_cache_pressure ------------------ diff --git a/Documentation/vm/overcommit-accounting b/Documentation/vm/overcommit-accounting index 706d7ed9d8d2..8eaa2fc4b8fa 100644 --- a/Documentation/vm/overcommit-accounting +++ b/Documentation/vm/overcommit-accounting @@ -8,7 +8,9 @@ The Linux kernel supports the following overcommit handling modes default. 1 - Always overcommit. Appropriate for some scientific - applications. + applications. Classic example is code using sparse arrays + and just relying on the virtual memory consisting almost + entirely of zero pages. 2 - Don't overcommit. The total address space commit for the system is not permitted to exceed swap + a @@ -18,6 +20,10 @@ The Linux kernel supports the following overcommit handling modes pages but will receive errors on memory allocation as appropriate. + Useful for applications that want to guarantee their + memory allocations will be available in the future + without having to initialize every page. + The overcommit policy is set via the sysctl `vm.overcommit_memory'. The overcommit percentage is set via `vm.overcommit_ratio'. |