Messages in this thread Patch in this message | | | Date | Sun, 23 Aug 1998 13:26:15 +0200 (CEST) | From | Rik van Riel <> | Subject | [PATCH] documentation update |
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Hi Linus,
the following patch updates the documentation for linux/Documentation/* and is fully complete as of 2.1.117.
It also updates the MAINTAINERS file, this time without that controversial line in it ;)
Please apply this for 2.1.118...
Rik. +-------------------------------------------------------------------+ | Linux memory management tour guide. H.H.vanRiel@phys.uu.nl | | Scouting Vries cubscout leader. http://www.phys.uu.nl/~riel/ | +-------------------------------------------------------------------+
--- MAINTAINERS.orig Sun Aug 23 13:19:12 1998 +++ MAINTAINERS Sun Aug 23 13:22:29 1998 @@ -367,6 +367,10 @@ L: linux-mac68k@wave.lm.com S: Maintained +MEMORY MANAGEMENT: +W: http://www.phys.uu.nl/~riel/mm-patch/ +L: linux-mm@kvack.org + MENUCONFIG: P: Michael Elizabeth Chastain M: mec@shout.net @@ -593,6 +597,12 @@ P: Martin Mares M: mj@atrey.karlin.mff.cuni.cz L: linux-video@atrey.karlin.mff.cuni.cz +S: Maintained + +SYSCTL DOCUMENTATION: (except networking) +P: Rik van Riel +M: H.H.vanRiel@phys.uu.nl +W: http://www.phys.uu.nl/~riel/ S: Maintained SYSV FILESYSTEM --- Documentation/sysctl/README.orig Wed Jun 24 23:30:07 1998 +++ Documentation/sysctl/README Sun Aug 23 12:34:48 1998 @@ -1,4 +1,4 @@ -Documentation for /proc/sys/*/* version 0.1 +Documentation for /proc/sys/ kernel version 2.1.117 (c) 1998, Rik van Riel <H.H.vanRiel@phys.uu.nl> 'Why', I hear you ask, 'would anyone even _want_ documentation @@ -58,9 +58,9 @@ debug/ <empty> dev/ device specific information (eg dev/cdrom/info) fs/ specific filesystems + filehandle, inode, dentry and quota tuning binfmt_misc <linux/Documentation/binfmt_misc.txt> kernel/ global kernel info / tuning - open file / inode tuning miscellaneous stuff net/ networking stuff, for documentation look in: <linux/Documentation/networking/> --- Documentation/sysctl/fs.txt.orig Tue Aug 11 18:28:56 1998 +++ Documentation/sysctl/fs.txt Sun Aug 23 12:35:49 1998 @@ -0,0 +1,116 @@ +Documentation for /proc/sys/fs/* kernel version 2.1.117 + (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. + +The files in this directory can be used to tune and monitor +miscellaneous and general things in the operation of the Linux +kernel. Since some of the files _can_ be used to screw up your +system, it is advisable to read both documentation and source +before actually making adjustments. + +Currently, these files are in /proc/sys/fs: +- dentry-state +- dquot-max +- dquot-nr +- file-max +- file-nr +- inode-max +- inode-nr +- inode-state + +Documentation for the files in /proc/sys/fs/binfmt_misc is +in Documentation/binfmt_misc.txt. + +============================================================== + +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 Jun 24 23:30:07 1998 +++ Documentation/sysctl/kernel.txt Sun Aug 23 13:18:04 1998 @@ -1,4 +1,4 @@ -Documentation for /proc/sys/kernel/* version 0.1 +Documentation for /proc/sys/kernel/* kernel version 2.1.117 (c) 1998, Rik van Riel <H.H.vanRiel@phys.uu.nl> For general info and legal blurb, please look in README. @@ -14,25 +14,25 @@ system, it is advisable to read both documentation and source before actually making adjustments. -Currently, these files are in /proc/sys/kernel: +These files might (depending on your configuration) show +up in /proc/sys/kernel: - ctrl-alt-del -- dentry-state - domainname -- file-max -- file-nr - hostname -- inode-max -- inode-nr -- inode-state +- htab-reclaim [ PPC only ] +- java-appletviewer [ binfmt_java, obsolete ] +- java-interpreter [ binfmt_java, obsolete ] - modprobe ==> Documentation/kmod.txt - osrelease - ostype - panic +- powersave-nap [ PPC only ] - printk -- real-root-dev ==> Documentation/initrd.txt -- reboot-cmd ==> SPARC specific -- securelevel +- real-root-dev ==> Documentation/initrd.txt +- reboot-cmd [ SPARC only ] +- sg-big-buff [ Generic SCSI interface (sg) ] - version +- zero-paged [ PPC only ] ============================================================== @@ -51,30 +51,6 @@ ============================================================== -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: These files can be controlled to set the domainname and @@ -86,52 +62,12 @@ ============================================================== -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. +htab-reclaim: (PPC only) +Setting this to a non-zero value, the PowerPC htab +(see Documentation/powerpc/ppc_htab.txt) is pruned +each time the system hits the idle loop. + ============================================================== osrelease, ostype & version: @@ -159,6 +95,13 @@ ============================================================== +powersave-nap: (PPC only) + +If set, Linux-PPC will use the 'nap' mode of powersaving, +otherwise the 'doze' mode will be used. + +============================================================== + printk: The four values in printk denote: console_loglevel, @@ -184,27 +127,30 @@ ============================================================== -securelevel: +reboot-cmd: (Sparc only) -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 ???) +??? This seems to be a way to give an argument to the Sparc +ROM/Flash boot loader. Maybe to tell it what to do after +rebooting. ??? ============================================================== -real-root-dev: (CONFIG_INITRD only) +sg-big-buff: -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. +This file shows the size of the generic SCSI (sg) buffer. +You can't tune it just yet, but you could change it on +compile time by editing include/scsi/sg.h and changing +the value of SG_BIG_BUFF. -============================================================== +There shouldn't be any reason to change this value. If +you can come up with one, you probably know what you +are doing anyway :) -reboot-cmd: (Sparc only) +============================================================== -??? This seems to be a way to give an argument to the Sparc -ROM/Flash boot loader. Maybe to tell it what to do after -rebooting. ??? +zero-paged: (PPC only) +When enabled (non-zero), Linux-PPC will pre-zero pages in +the idle loop, possibly speeding up get_free_pages. Since +this only affects what the idle loop is doing, you should +enable this and see if anything changes. --- Documentation/sysctl/vm.txt.orig Wed Jun 24 23:30:07 1998 +++ Documentation/sysctl/vm.txt Sun Aug 23 12:38:27 1998 @@ -1,4 +1,4 @@ -Documentation for /proc/sys/vm/* version 0.1 +Documentation for /proc/sys/vm/* kernel version 2.1.117 (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 @@ -101,8 +102,9 @@ min_percent -- this is the minimum percentage of memory that should be spent on buffer memory borrow_percent -- when Linux is short on memory, and the - buffer cache uses more memory, free pages - are stolen from it + buffer cache uses more memory than this, + the MM subsystem will prune the buffercache + more heavily than other memory max_percent -- this is the maximum amount of memory that can be used for buffer memory @@ -112,25 +114,17 @@ 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. ============================================================== @@ -210,11 +204,29 @@ This file does exactly the same as buffermem, only this file controls the struct page_cache, and thus controls -the amount of memory allowed for memory mapping of files. +the amount of memory allowed for memory mapping and generic +caching of files. 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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