From db0fb1848a645b0b1b033765f3a5244e7afd2e3c Mon Sep 17 00:00:00 2001 From: Peter W Morreale Date: Thu, 15 Jan 2009 13:50:42 -0800 Subject: Update of Documentation: vm.txt and proc.txt Update Documentation/sysctl/vm.txt and Documentation/filesystems/proc.txt. More specifically, the section on /proc/sys/vm in Documentation/filesystems/proc.txt was removed and a link to Documentation/sysctl/vm.txt added. Most of the verbiage from proc.txt was simply moved in vm.txt, with new addtional text for "swappiness" and "stat_interval". Signed-off-by: Peter W Morreale Acked-by: Randy Dunlap Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/filesystems/proc.txt | 288 +------------------------------------ 1 file changed, 2 insertions(+), 286 deletions(-) (limited to 'Documentation/filesystems') diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index d105eb45282a..bbebc3a43ac0 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -1371,292 +1371,8 @@ auto_msgmni default value is 1. 2.4 /proc/sys/vm - The virtual memory subsystem ----------------------------------------------- -The files in this directory can be used to tune the operation of the virtual -memory (VM) subsystem of the Linux kernel. - -vfs_cache_pressure ------------------- - -Controls the tendency of the kernel to reclaim the memory which is used for -caching of directory and inode objects. - -At the default value of vfs_cache_pressure=100 the kernel will attempt to -reclaim dentries and inodes at a "fair" rate with respect to pagecache and -swapcache reclaim. Decreasing vfs_cache_pressure causes the kernel to prefer -to retain dentry and inode caches. Increasing vfs_cache_pressure beyond 100 -causes the kernel to prefer to reclaim dentries and inodes. - -dirty_background_bytes ----------------------- - -Contains the amount of dirty memory at which the pdflush background writeback -daemon will start writeback. - -If dirty_background_bytes is written, dirty_background_ratio becomes a function -of its value (dirty_background_bytes / the amount of dirtyable system memory). - -dirty_background_ratio ----------------------- - -Contains, as a percentage of the dirtyable system memory (free pages + mapped -pages + file cache, not including locked pages and HugePages), the number of -pages at which the pdflush background writeback daemon will start writing out -dirty data. - -If dirty_background_ratio is written, dirty_background_bytes becomes a function -of its value (dirty_background_ratio * the amount of dirtyable system memory). - -dirty_bytes ------------ - -Contains the amount of dirty memory at which a process generating disk writes -will itself start writeback. - -If dirty_bytes is written, dirty_ratio becomes a function of its value -(dirty_bytes / the amount of dirtyable system memory). - -dirty_ratio ------------ - -Contains, as a percentage of the dirtyable system memory (free pages + mapped -pages + file cache, not including locked pages and HugePages), the number of -pages at which a process which is generating disk writes will itself start -writing out dirty data. - -If dirty_ratio is written, dirty_bytes becomes a function of its value -(dirty_ratio * the amount of dirtyable system memory). - -dirty_writeback_centisecs -------------------------- - -The pdflush writeback daemons will periodically wake up and write `old' data -out to disk. This tunable expresses the interval between those wakeups, in -100'ths of a second. - -Setting this to zero disables periodic writeback altogether. - -dirty_expire_centisecs ----------------------- - -This tunable is used to define when dirty data is old enough to be eligible -for writeout by the pdflush daemons. It is expressed in 100'ths of a second. -Data which has been dirty in-memory for longer than this interval will be -written out next time a pdflush daemon wakes up. - -highmem_is_dirtyable --------------------- - -Only present if CONFIG_HIGHMEM is set. - -This defaults to 0 (false), meaning that the ratios set above are calculated -as a percentage of lowmem only. This protects against excessive scanning -in page reclaim, swapping and general VM distress. - -Setting this to 1 can be useful on 32 bit machines where you want to make -random changes within an MMAPed file that is larger than your available -lowmem without causing large quantities of random IO. Is is safe if the -behavior of all programs running on the machine is known and memory will -not be otherwise stressed. - -legacy_va_layout ----------------- - -If non-zero, this sysctl disables the new 32-bit mmap mmap layout - the kernel -will use the legacy (2.4) layout for all processes. - -lowmem_reserve_ratio ---------------------- - -For some specialised workloads on highmem machines it is dangerous for -the kernel to allow process memory to be allocated from the "lowmem" -zone. This is because that memory could then be pinned via the mlock() -system call, or by unavailability of swapspace. - -And on large highmem machines this lack of reclaimable lowmem memory -can be fatal. - -So the Linux page allocator has a mechanism which prevents allocations -which _could_ use highmem from using too much lowmem. This means that -a certain amount of lowmem is defended from the possibility of being -captured into pinned user memory. - -(The same argument applies to the old 16 megabyte ISA DMA region. This -mechanism will also defend that region from allocations which could use -highmem or lowmem). - -The `lowmem_reserve_ratio' tunable determines how aggressive the kernel is -in defending these lower zones. - -If you have a machine which uses highmem or ISA DMA and your -applications are using mlock(), or if you are running with no swap then -you probably should change the lowmem_reserve_ratio setting. - -The lowmem_reserve_ratio is an array. You can see them by reading this file. -- -% cat /proc/sys/vm/lowmem_reserve_ratio -256 256 32 -- -Note: # of this elements is one fewer than number of zones. Because the highest - zone's value is not necessary for following calculation. - -But, these values are not used directly. The kernel calculates # of protection -pages for each zones from them. These are shown as array of protection pages -in /proc/zoneinfo like followings. (This is an example of x86-64 box). -Each zone has an array of protection pages like this. - -- -Node 0, zone DMA - pages free 1355 - min 3 - low 3 - high 4 - : - : - numa_other 0 - protection: (0, 2004, 2004, 2004) - ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - pagesets - cpu: 0 pcp: 0 - : -- -These protections are added to score to judge whether this zone should be used -for page allocation or should be reclaimed. - -In this example, if normal pages (index=2) are required to this DMA zone and -pages_high is used for watermark, the kernel judges this zone should not be -used because pages_free(1355) is smaller than watermark + protection[2] -(4 + 2004 = 2008). If this protection value is 0, this zone would be used for -normal page requirement. If requirement is DMA zone(index=0), protection[0] -(=0) is used. - -zone[i]'s protection[j] is calculated by following expression. - -(i < j): - zone[i]->protection[j] - = (total sums of present_pages from zone[i+1] to zone[j] on the node) - / lowmem_reserve_ratio[i]; -(i = j): - (should not be protected. = 0; -(i > j): - (not necessary, but looks 0) - -The default values of lowmem_reserve_ratio[i] are - 256 (if zone[i] means DMA or DMA32 zone) - 32 (others). -As above expression, they are reciprocal number of ratio. -256 means 1/256. # of protection pages becomes about "0.39%" of total present -pages of higher zones on the node. - -If you would like to protect more pages, smaller values are effective. -The minimum value is 1 (1/1 -> 100%). - -page-cluster ------------- - -page-cluster controls the number of pages which are written to swap in -a single attempt. The swap I/O size. - -It is a logarithmic value - setting it to zero means "1 page", setting -it to 1 means "2 pages", setting it to 2 means "4 pages", etc. - -The default value is three (eight pages at a time). There may be some -small benefits in tuning this to a different value if your workload is -swap-intensive. - -overcommit_memory ------------------ - -Controls overcommit of system memory, possibly allowing processes -to allocate (but not use) more memory than is actually available. - - -0 - Heuristic overcommit handling. Obvious overcommits of - address space are refused. Used for a typical system. It - ensures a seriously wild allocation fails while allowing - overcommit to reduce swap usage. root is allowed to - allocate slightly more memory in this mode. This is the - default. - -1 - Always overcommit. Appropriate for some scientific - applications. - -2 - Don't overcommit. The total address space commit - for the system is not permitted to exceed swap plus a - configurable percentage (default is 50) of physical RAM. - Depending on the percentage you use, in most situations - this means a process will not be killed while attempting - to use already-allocated memory but will receive errors - on memory allocation as appropriate. - -overcommit_ratio ----------------- - -Percentage of physical memory size to include in overcommit calculations -(see above.) - -Memory allocation limit = swapspace + physmem * (overcommit_ratio / 100) - - swapspace = total size of all swap areas - physmem = size of physical memory in system - -nr_hugepages and hugetlb_shm_group ----------------------------------- - -nr_hugepages configures number of hugetlb page reserved for the system. - -hugetlb_shm_group contains group id that is allowed to create SysV shared -memory segment using hugetlb page. - -hugepages_treat_as_movable --------------------------- - -This parameter is only useful when kernelcore= is specified at boot time to -create ZONE_MOVABLE for pages that may be reclaimed or migrated. Huge pages -are not movable so are not normally allocated from ZONE_MOVABLE. A non-zero -value written to hugepages_treat_as_movable allows huge pages to be allocated -from ZONE_MOVABLE. - -Once enabled, the ZONE_MOVABLE is treated as an area of memory the huge -pages pool can easily grow or shrink within. Assuming that applications are -not running that mlock() a lot of memory, it is likely the huge pages pool -can grow to the size of ZONE_MOVABLE by repeatedly entering the desired value -into nr_hugepages and triggering page reclaim. - -laptop_mode ------------ - -laptop_mode is a knob that controls "laptop mode". All the things that are -controlled by this knob are discussed in Documentation/laptops/laptop-mode.txt. - -block_dump ----------- - -block_dump enables block I/O debugging when set to a nonzero value. More -information on block I/O debugging is in Documentation/laptops/laptop-mode.txt. - -swap_token_timeout ------------------- - -This file contains valid hold time of swap out protection token. The Linux -VM has token based thrashing control mechanism and uses the token to prevent -unnecessary page faults in thrashing situation. The unit of the value is -second. The value would be useful to tune thrashing behavior. - -drop_caches ------------ - -Writing to this will cause the kernel to drop clean caches, dentries and -inodes from memory, causing that memory to become free. - -To free pagecache: - echo 1 > /proc/sys/vm/drop_caches -To free dentries and inodes: - echo 2 > /proc/sys/vm/drop_caches -To free pagecache, dentries and inodes: - 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. +Please see: Documentation/sysctls/vm.txt for a description of these +entries. 2.5 /proc/sys/dev - Device specific parameters -- cgit v1.2.3 From 096abd77038a2ff74efd194d074eadcde80fb97d Mon Sep 17 00:00:00 2001 From: James Lentini Date: Thu, 8 Jan 2009 13:13:26 -0500 Subject: update port number in NFS/RDMA documentation Update the NFS/RDMA documentation to use the new port number assigned by IANA. Signed-off-by: James Lentini Signed-off-by: J. Bruce Fields --- Documentation/filesystems/nfs-rdma.txt | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'Documentation/filesystems') diff --git a/Documentation/filesystems/nfs-rdma.txt b/Documentation/filesystems/nfs-rdma.txt index 44bd766f2e5d..85eaeaddd27c 100644 --- a/Documentation/filesystems/nfs-rdma.txt +++ b/Documentation/filesystems/nfs-rdma.txt @@ -251,7 +251,7 @@ NFS/RDMA Setup Instruct the server to listen on the RDMA transport: - $ echo rdma 2050 > /proc/fs/nfsd/portlist + $ echo rdma 20049 > /proc/fs/nfsd/portlist - On the client system @@ -263,7 +263,7 @@ NFS/RDMA Setup Regardless of how the client was built (module or built-in), use this command to mount the NFS/RDMA server: - $ mount -o rdma,port=2050 :/ /mnt + $ mount -o rdma,port=20049 :/ /mnt To verify that the mount is using RDMA, run "cat /proc/mounts" and check the "proto" field for the given mount. -- cgit v1.2.3 From 27ad27993313312a4ad0047d0a944c425cd511a5 Mon Sep 17 00:00:00 2001 From: Artem Bityutskiy Date: Thu, 29 Jan 2009 16:34:30 +0200 Subject: UBIFS: remove fast unmounting This UBIFS feature has never worked properly, and it was a mistake to add it because we simply have no use-cases. So, lets still accept the fast_unmount mount option, but ignore it. This does not change much, because UBIFS commit in sync_fs anyway, and sync_fs is called while unmounting. Signed-off-by: Artem Bityutskiy --- Documentation/filesystems/ubifs.txt | 7 ------- 1 file changed, 7 deletions(-) (limited to 'Documentation/filesystems') diff --git a/Documentation/filesystems/ubifs.txt b/Documentation/filesystems/ubifs.txt index 84da2a4ba25a..12fedb7834c6 100644 --- a/Documentation/filesystems/ubifs.txt +++ b/Documentation/filesystems/ubifs.txt @@ -79,13 +79,6 @@ Mount options (*) == default. -norm_unmount (*) commit on unmount; the journal is committed - when the file-system is unmounted so that the - next mount does not have to replay the journal - and it becomes very fast; -fast_unmount do not commit on unmount; this option makes - unmount faster, but the next mount slower - because of the need to replay the journal. bulk_read read more in one go to take advantage of flash media that read faster sequentially no_bulk_read (*) do not bulk-read -- cgit v1.2.3 From 9e9e3cbc62da43c66e894d5a61fa08b427e25202 Mon Sep 17 00:00:00 2001 From: Evgeniy Polyakov Date: Thu, 29 Jan 2009 14:25:09 -0800 Subject: mm: OOM documentation update Signed-off-by: Evgeniy Polyakov Acked-by: David Rientjes Cc: Randy Dunlap Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/filesystems/proc.txt | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) (limited to 'Documentation/filesystems') diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index bbebc3a43ac0..a87be42f8211 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -2027,6 +2027,34 @@ increase the likelihood of this process being killed by the oom-killer. Valid values are in the range -16 to +15, plus the special value -17, which disables oom-killing altogether for this process. +The process to be killed in an out-of-memory situation is selected among all others +based on its badness score. This value equals the original memory size of the process +and is then updated according to its CPU time (utime + stime) and the +run time (uptime - start time). The longer it runs the smaller is the score. +Badness score is divided by the square root of the CPU time and then by +the double square root of the run time. + +Swapped out tasks are killed first. Half of each child's memory size is added to +the parent's score if they do not share the same memory. Thus forking servers +are the prime candidates to be killed. Having only one 'hungry' child will make +parent less preferable than the child. + +/proc//oom_score shows process' current badness score. + +The following heuristics are then applied: + * if the task was reniced, its score doubles + * superuser or direct hardware access tasks (CAP_SYS_ADMIN, CAP_SYS_RESOURCE + or CAP_SYS_RAWIO) have their score divided by 4 + * if oom condition happened in one cpuset and checked task does not belong + to it, its score is divided by 8 + * the resulting score is multiplied by two to the power of oom_adj, i.e. + points <<= oom_adj when it is positive and + points >>= -(oom_adj) otherwise + +The task with the highest badness score is then selected and its children +are killed, process itself will be killed in an OOM situation when it does +not have children or some of them disabled oom like described above. + 2.13 /proc//oom_score - Display current oom-killer score ------------------------------------------------------------- -- cgit v1.2.3 From 97c44836cdec1ea713a15d84098a1a908157e68f Mon Sep 17 00:00:00 2001 From: "Timothy S. Nelson" Date: Fri, 30 Jan 2009 06:12:47 +1100 Subject: PCI: return error on failure to read PCI ROMs This patch makes the ROM reading code return an error to user space if the size of the ROM read is equal to 0. The patch also emits a warnings if the contents of the ROM are invalid, and documents the effects of the "enable" file on ROM reading. Signed-off-by: Timothy S. Nelson Acked-by: Alex Villacis-Lasso Signed-off-by: Jesse Barnes --- Documentation/filesystems/sysfs-pci.txt | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'Documentation/filesystems') diff --git a/Documentation/filesystems/sysfs-pci.txt b/Documentation/filesystems/sysfs-pci.txt index 68ef48839c04..9f8740ca3f3b 100644 --- a/Documentation/filesystems/sysfs-pci.txt +++ b/Documentation/filesystems/sysfs-pci.txt @@ -9,6 +9,7 @@ that support it. For example, a given bus might look like this: | |-- class | |-- config | |-- device + | |-- enable | |-- irq | |-- local_cpus | |-- resource @@ -32,6 +33,7 @@ files, each with their own function. class PCI class (ascii, ro) config PCI config space (binary, rw) device PCI device (ascii, ro) + enable Whether the device is enabled (ascii, rw) irq IRQ number (ascii, ro) local_cpus nearby CPU mask (cpumask, ro) resource PCI resource host addresses (ascii, ro) @@ -57,10 +59,19 @@ used to do actual device programming from userspace. Note that some platforms don't support mmapping of certain resources, so be sure to check the return value from any attempted mmap. +The 'enable' file provides a counter that indicates how many times the device +has been enabled. If the 'enable' file currently returns '4', and a '1' is +echoed into it, it will then return '5'. Echoing a '0' into it will decrease +the count. Even when it returns to 0, though, some of the initialisation +may not be reversed. + The 'rom' file is special in that it provides read-only access to the device's ROM file, if available. It's disabled by default, however, so applications should write the string "1" to the file to enable it before attempting a read -call, and disable it following the access by writing "0" to the file. +call, and disable it following the access by writing "0" to the file. Note +that the device must be enabled for a rom read to return data succesfully. +In the event a driver is not bound to the device, it can be enabled using the +'enable' file, documented above. Accessing legacy resources through sysfs ---------------------------------------- -- cgit v1.2.3 From f8a1af6bbc63218cabce742a7a291ac7c08bbd00 Mon Sep 17 00:00:00 2001 From: Mike Murphy Date: Sun, 22 Feb 2009 01:19:23 -0500 Subject: PATCH [2/2] Documentation/filesystems/sysfs.txt: fix descriptions of device attributes Fix descriptions of device attributes to be consistent with the actual implementations in include/linux/device.h Signed-off-by: Mike Murphy Signed-off-by: Linus Torvalds --- Documentation/filesystems/sysfs.txt | 50 +++++++++++++++++++++---------------- 1 file changed, 28 insertions(+), 22 deletions(-) (limited to 'Documentation/filesystems') diff --git a/Documentation/filesystems/sysfs.txt b/Documentation/filesystems/sysfs.txt index 9e9c348275a9..7e81e37c0b1e 100644 --- a/Documentation/filesystems/sysfs.txt +++ b/Documentation/filesystems/sysfs.txt @@ -2,8 +2,10 @@ sysfs - _The_ filesystem for exporting kernel objects. Patrick Mochel +Mike Murphy -10 January 2003 +Revised: 22 February 2009 +Original: 10 January 2003 What it is: @@ -64,12 +66,13 @@ An attribute definition is simply: struct attribute { char * name; + struct module *owner; mode_t mode; }; -int sysfs_create_file(struct kobject * kobj, struct attribute * attr); -void sysfs_remove_file(struct kobject * kobj, struct attribute * attr); +int sysfs_create_file(struct kobject * kobj, const struct attribute * attr); +void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr); A bare attribute contains no means to read or write the value of the @@ -80,9 +83,11 @@ a specific object type. For example, the driver model defines struct device_attribute like: struct device_attribute { - struct attribute attr; - ssize_t (*show)(struct device * dev, char * buf); - ssize_t (*store)(struct device * dev, const char * buf); + struct attribute attr; + ssize_t (*show)(struct device *dev, struct device_attribute *attr, + char *buf); + ssize_t (*store)(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count); }; int device_create_file(struct device *, struct device_attribute *); @@ -90,12 +95,8 @@ void device_remove_file(struct device *, struct device_attribute *); It also defines this helper for defining device attributes: -#define DEVICE_ATTR(_name, _mode, _show, _store) \ -struct device_attribute dev_attr_##_name = { \ - .attr = {.name = __stringify(_name) , .mode = _mode }, \ - .show = _show, \ - .store = _store, \ -}; +#define DEVICE_ATTR(_name, _mode, _show, _store) \ +struct device_attribute dev_attr_##_name = __ATTR(_name, _mode, _show, _store) For example, declaring @@ -107,9 +108,9 @@ static struct device_attribute dev_attr_foo = { .attr = { .name = "foo", .mode = S_IWUSR | S_IRUGO, + .show = show_foo, + .store = store_foo, }, - .show = show_foo, - .store = store_foo, }; @@ -161,10 +162,12 @@ To read or write attributes, show() or store() methods must be specified when declaring the attribute. The method types should be as simple as those defined for device attributes: - ssize_t (*show)(struct device * dev, char * buf); - ssize_t (*store)(struct device * dev, const char * buf); +ssize_t (*show)(struct device * dev, struct device_attribute * attr, + char * buf); +ssize_t (*store)(struct device * dev, struct device_attribute * attr, + const char * buf); -IOW, they should take only an object and a buffer as parameters. +IOW, they should take only an object, an attribute, and a buffer as parameters. sysfs allocates a buffer of size (PAGE_SIZE) and passes it to the @@ -299,14 +302,16 @@ The following interface layers currently exist in sysfs: Structure: struct device_attribute { - struct attribute attr; - ssize_t (*show)(struct device * dev, char * buf); - ssize_t (*store)(struct device * dev, const char * buf); + struct attribute attr; + ssize_t (*show)(struct device *dev, struct device_attribute *attr, + char *buf); + ssize_t (*store)(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count); }; Declaring: -DEVICE_ATTR(_name, _str, _mode, _show, _store); +DEVICE_ATTR(_name, _mode, _show, _store); Creation/Removal: @@ -342,7 +347,8 @@ Structure: struct driver_attribute { struct attribute attr; ssize_t (*show)(struct device_driver *, char * buf); - ssize_t (*store)(struct device_driver *, const char * buf); + ssize_t (*store)(struct device_driver *, const char * buf, + size_t count); }; Declaring: -- cgit v1.2.3 From edf2e2811efa9304ebe14f778d33b764cfd58b7a Mon Sep 17 00:00:00 2001 From: Phillip Lougher Date: Thu, 5 Mar 2009 00:40:13 +0000 Subject: Squashfs: fix documentation typo, Cramfs filesystem limit is 256 MiB Signed-off-by: Phillip Lougher --- Documentation/filesystems/squashfs.txt | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Documentation/filesystems') diff --git a/Documentation/filesystems/squashfs.txt b/Documentation/filesystems/squashfs.txt index 3e79e4a7a392..b324c033035a 100644 --- a/Documentation/filesystems/squashfs.txt +++ b/Documentation/filesystems/squashfs.txt @@ -22,7 +22,7 @@ Squashfs filesystem features versus Cramfs: Squashfs Cramfs -Max filesystem size: 2^64 16 MiB +Max filesystem size: 2^64 256 MiB Max file size: ~ 2 TiB 16 MiB Max files: unlimited unlimited Max directories: unlimited unlimited -- cgit v1.2.3