Messages in this thread Patch in this message | | | Date | Tue, 11 Aug 1998 19:57:58 +0200 (CEST) | From | Rik van Riel <> | Subject | [PATCH] documentation update |
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Hi Linus,
the following patch updates Documentation/sysctl/* and the MAINTAINERS file.
It still misses some of the new files in /proc/sys/*, but I currently miss the time to dig around in the source to find out exactly what the different things mean.
Please apply this patch, I promise the docs _will_ be up-to-date before 2.2 ships :-)
Rik. +-------------------------------------------------------------------+ | Linux memory management tour guide. H.H.vanRiel@phys.uu.nl | | Scouting Vries cubscout leader. http://www.phys.uu.nl/~riel/ | +-------------------------------------------------------------------+
--- MAINTAINERS.orig Tue Aug 11 19:39:25 1998 +++ MAINTAINERS Tue Aug 11 19:48:42 1998 @@ -367,6 +367,11 @@ L: linux-mac68k@wave.lm.com S: Maintained +MEMORY MANAGEMENT: +L: linux-mm@kvack.org +W: http://www.phys.uu.nl/~riel/mm-patch/ +S: Maintained + MENUCONFIG: P: Michael Elizabeth Chastain M: mec@shout.net @@ -593,6 +598,12 @@ P: Martin Mares M: mj@atrey.karlin.mff.cuni.cz L: linux-video@atrey.karlin.mff.cuni.cz +S: Maintained + +SYSCTL DOCUMENTATION (except networking stuff): +P: Rik van Riel +M: H.H.vanRiel@phys.uu.nl +W: http://www.phys.uu.nl/~riel/ S: Maintained SYSV FILESYSTEM --- Documentation/sysctl/fs.txt.orig Tue Aug 11 18:28:56 1998 +++ Documentation/sysctl/fs.txt Tue Aug 11 19:35:42 1998 @@ -0,0 +1,110 @@ +Documentation for /proc/sys/fs/* kernel version 2.1.115 + (c) 1998, Rik van Riel <H.H.vanRiel@phys.uu.nl> + +For general info and legal blurb, please look in README. + +============================================================== + +This file contains documentation for the sysctl files in +/proc/sys/fs/ and is valid for Linux kernel version 2.1. + +These files are used to tune the way in which the kernel caches +filesystem metadata and inodes. + +Currently, these files are in /proc/sys/fs: +- dentry-state +- dquot-max +- dquot-nr +- file-max +- file-nr +- inode-max +- inode-nr +- inode-state + +============================================================== + +dentry-state: + +From linux/fs/dentry.c: +-------------------------------------------------------------- +struct { + int nr_dentry; + int nr_unused; + int age_limit; /* age in seconds */ + int want_pages; /* pages requested by system */ + int dummy[2]; +} dentry_stat = {0, 0, 45, 0,}; +-------------------------------------------------------------- + +Dentries are dynamically allocated and deallocated, and +nr_dentry seems to be 0 all the time. Hence it's safe to +assume that only nr_unused, age_limit and want_pages are +used. Nr_unused seems to be exactly what its name says. +Age_limit is the age in seconds after which dcache entries +can be reclaimed when memory is short and want_pages is +nonzero when shrink_dcache_pages() has been called and the +dcache isn't pruned yet. + +============================================================== + +dquot-max & dquot-nr: + +The file dquot-max shows the maximum number of cached disk +quota entries. + +The file dquot-nr shows the number of allocated disk quota +entries and the number of free disk quota entries. + +If the number of free cached disk quotas is very low and +you have some awesome number of simultaneous system users, +you might want to raise the limit. + +============================================================== + +file-max & file-nr: + +The kernel allocates file handles dynamically, but as yet it +doesn't free them again. + +The value in file-max denotes the maximum number of file- +handles that the Linux kernel will allocate. When you get lots +of error messages about running out of file handles, you might +want to increase this limit. + +The three values in file-nr denote the number of allocated +file handles, the number of used file handles and the maximum +number of file handles. When the allocated file handles come +close to the maximum, but the number of actually used ones is +far behind, you've encountered a peak in your usage of file +handles and you don't need to increase the maximum. + +============================================================== + +inode-max, inode-nr & inode-state: + +As with file handles, the kernel allocates the inode structures +dynamically, but can't free them yet. + +The value in inode-max denotes the maximum number of inode +handlers. This value should be 3-4 times larger than the value +in file-max, since stdin, stdout and network sockets also +need an inode struct to handle them. When you regularly run +out of inodes, you need to increase this value. + +The file inode-nr contains the first two items from +inode-state, so we'll skip to that file... + +Inode-state contains three actual numbers and four dummies. +The actual numbers are, in order of appearance, nr_inodes, +nr_free_inodes and preshrink. + +Nr_inodes stands for the number of inodes the system has +allocated, this can be slightly more than inode-max because +Linux allocates them one pageful at a time. + +Nr_free_inodes represents the number of free inodes (?) and +preshrink is nonzero when the nr_inodes > inode-max and the +system needs to prune the inode list instead of allocating +more. + + --- Documentation/sysctl/kernel.txt.orig Wed Jul 8 14:45:40 1998 +++ Documentation/sysctl/kernel.txt Tue Aug 11 19:36:50 1998 @@ -1,4 +1,4 @@ -Documentation for /proc/sys/kernel/* version 0.1 +Documentation for /proc/sys/kernel/* kernel version 2.1.115 (c) 1998, Rik van Riel <H.H.vanRiel@phys.uu.nl> For general info and legal blurb, please look in README. @@ -16,22 +16,15 @@ Currently, these files are in /proc/sys/kernel: - ctrl-alt-del -- dentry-state - domainname -- file-max -- file-nr - hostname -- inode-max -- inode-nr -- inode-state - modprobe ==> Documentation/kmod.txt - osrelease - ostype - panic - printk -- real-root-dev ==> Documentation/initrd.txt -- reboot-cmd ==> SPARC specific -- securelevel +- real-root-dev ==> Documentation/initrd.txt +- reboot-cmd [ SPARC only ] - version ============================================================== @@ -51,31 +44,7 @@ ============================================================== -dentry-state: - -From linux/fs/dentry.c: --------------------------------------------------------------- -struct { - int nr_dentry; - int nr_unused; - int age_limit; /* age in seconds */ - int want_pages; /* pages requested by system */ - int dummy[2]; -} dentry_stat = {0, 0, 45, 0,}; --------------------------------------------------------------- - -Dentries are dynamically allocated and deallocated, and -nr_dentry seems to be 0 all the time. Hence it's safe to -assume that only nr_unused, age_limit and want_pages are -used. Nr_unused seems to be exactly what its name says. -Age_limit is the age in seconds after which dcache entries -can be reclaimed when memory is short and want_pages is -nonzero when shrink_dcache_pages() has been called and the -dcache isn't pruned yet. - -============================================================== - -domainname & hostname: +domainname & hostname These files can be controlled to set the domainname and hostname of your box. For the classic darkstar.frop.org @@ -86,54 +55,6 @@ ============================================================== -file-max & file-nr: - -The kernel allocates file handles dynamically, but as yet it -doesn't free them again. - -The value in file-max denotes the maximum number of file- -handles that the Linux kernel will allocate. When you get lots -of error messages about running out of file handles, you might -want to increase this limit. - -The three values in file-nr denote the number of allocated -file handles, the number of used file handles and the maximum -number of file handles. When the allocated file handles come -close to the maximum, but the number of actually used ones is -far behind, you've encountered a peak in your usage of file -handles and you don't need to increase the maximum. - -============================================================== - -inode-max, inode-nr & inode-state: - -As with file handles, the kernel allocates the inode structures -dynamically, but can't free them yet. - -The value in inode-max denotes the maximum number of inode -handlers. This value should be 3-4 times larger than the value -in file-max, since stdin, stdout and network sockets also -need an inode struct to handle them. When you regularly run -out of inodes, you need to increase this value. - -The file inode-nr contains the first two items from -inode-state, so we'll skip to that file... - -Inode-state contains three actual numbers and four dummies. -The actual numbers are, in order of appearance, nr_inodes, -nr_free_inodes and preshrink. - -Nr_inodes stands for the number of inodes the system has -allocated, this can be slightly more than inode-max because -Linux allocates them one pageful at a time. - -Nr_free_inodes represents the number of free inodes (?) and -preshrink is nonzero when the nr_inodes > inode-max and the -system needs to prune the inode list instead of allocating -more. - -============================================================== - osrelease, ostype & version: # cat osrelease @@ -181,24 +102,6 @@ these variables aren't put inside a structure, so their order in-core isn't formally guaranteed and garbage values _might_ occur when the compiler changes. (???) - -============================================================== - -securelevel: - -When the value in this file is nonzero, root is prohibited -from: -- changing the immutable and append-only flags on files -- changing sysctl things (limited ???) - -============================================================== - -real-root-dev: (CONFIG_INITRD only) - -This file is used to configure the real root device when using -an initial ramdisk to configure the system before switching to -the 'real' root device. See linux/Documentation/initrd.txt for -more info. ============================================================== --- Documentation/sysctl/vm.txt.orig Tue Aug 11 19:20:38 1998 +++ Documentation/sysctl/vm.txt Tue Aug 11 19:28:03 1998 @@ -1,4 +1,4 @@ -Documentation for /proc/sys/vm/* version 0.1 +Documentation for /proc/sys/vm/* kernel version 2.1.115 (c) 1998, Rik van Riel <H.H.vanRiel@phys.uu.nl> For general info and legal blurb, please look in README. @@ -20,6 +20,7 @@ - kswapd - overcommit_memory - pagecache +- pagetable_cache - swapctl - swapout_interval @@ -112,25 +113,17 @@ This file contains the values in the struct freepages. That struct contains three members: min, low and high. -Although the goal of the Linux memory management subsystem -is to avoid fragmentation and make large chunks of free -memory (so that we can hand out DMA buffers and such), there -still are some page-based limits in the system, mainly to -make sure we don't waste too much memory trying to get large -free area's. - The meaning of the numbers is: freepages.min When the number of free pages in the system reaches this number, only the kernel can allocate more memory. -freepages.low If memory is too fragmented, the swapout - daemon is started, except when the number - of free pages is larger than freepages.low. -freepages.high The swapping daemon exits when memory is - sufficiently defragmented, when the number - of free pages reaches freepages.high or when - it has tried the maximum number of times. +freepages.low If the number of free pages gets below this + point, the kernel starts swapping agressively. +freepages.high The kernel tries to keep up to this amount of + memory free; if memory comes below this point, + the kernel gently starts swapping in the hopes + that it never has to do real agressive swapping. ============================================================== @@ -215,6 +208,23 @@ You don't want the minimum level to be too low, otherwise your system might thrash when memory is tight or fragmentation is high... + +============================================================== + +pagetable_cache: + +The kernel keeps a number of page tables in a per-processor +cache (this helps a lot on SMP systems). The cache size for +each processor will be between the low and the high value. + +On a low-memory, single CPU system you can safely set these +values to 0 so you don't waste the memory. On SMP systems it +is used so that the system can do fast pagetable allocations +without having to aquire the kernel memory lock. + +For large systems, the settings are probably OK. For normal +systems they won't hurt a bit. For small systems (<16MB ram) +it might be advantageous to set both values to 0. ==============================================================
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