diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/DMA-API-HOWTO.txt | 9 | ||||
| -rw-r--r-- | Documentation/IPMI.txt | 18 | ||||
| -rw-r--r-- | Documentation/block/cfq-iosched.txt | 58 | ||||
| -rw-r--r-- | Documentation/blockdev/nbd.txt | 38 | ||||
| -rw-r--r-- | Documentation/cgroups/blkio-controller.txt | 37 | ||||
| -rw-r--r-- | Documentation/coccinelle.txt | 4 | ||||
| -rw-r--r-- | Documentation/kbuild/kconfig-language.txt | 23 | ||||
| -rw-r--r-- | Documentation/kbuild/kconfig.txt | 6 | ||||
| -rw-r--r-- | Documentation/kernel-parameters.txt | 5 |
9 files changed, 119 insertions, 79 deletions
diff --git a/Documentation/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt index 4a4fb295cee..14129f149a7 100644 --- a/Documentation/DMA-API-HOWTO.txt +++ b/Documentation/DMA-API-HOWTO.txt @@ -488,9 +488,10 @@ will invoke the generic mapping error check interface. Doing so will ensure that the mapping code will work correctly on all dma implementations without any dependency on the specifics of the underlying implementation. Using the returned address without checking for errors could result in failures ranging -from panics to silent data corruption. Couple of example of incorrect ways to -check for errors that make assumptions about the underlying dma implementation -are as follows and these are applicable to dma_map_page() as well. +from panics to silent data corruption. A couple of examples of incorrect ways +to check for errors that make assumptions about the underlying dma +implementation are as follows and these are applicable to dma_map_page() as +well. Incorrect example 1: dma_addr_t dma_handle; @@ -751,7 +752,7 @@ Example 1: dma_unmap_single(dma_handle1); map_error_handling1: -Example 2: (if buffers are allocated a loop, unmap all mapped buffers when +Example 2: (if buffers are allocated in a loop, unmap all mapped buffers when mapping error is detected in the middle) dma_addr_t dma_addr; diff --git a/Documentation/IPMI.txt b/Documentation/IPMI.txt index 16eb4c9e923..f13c9132e9f 100644 --- a/Documentation/IPMI.txt +++ b/Documentation/IPMI.txt @@ -348,34 +348,40 @@ You can change this at module load time (for a module) with: modprobe ipmi_si.o type=<type1>,<type2>.... ports=<port1>,<port2>... addrs=<addr1>,<addr2>... - irqs=<irq1>,<irq2>... trydefaults=[0|1] + irqs=<irq1>,<irq2>... regspacings=<sp1>,<sp2>,... regsizes=<size1>,<size2>,... regshifts=<shift1>,<shift2>,... slave_addrs=<addr1>,<addr2>,... force_kipmid=<enable1>,<enable2>,... kipmid_max_busy_us=<ustime1>,<ustime2>,... unload_when_empty=[0|1] + trydefaults=[0|1] trydmi=[0|1] tryacpi=[0|1] + tryplatform=[0|1] trypci=[0|1] -Each of these except si_trydefaults is a list, the first item for the +Each of these except try... items is a list, the first item for the first interface, second item for the second interface, etc. The si_type may be either "kcs", "smic", or "bt". If you leave it blank, it defaults to "kcs". -If you specify si_addrs as non-zero for an interface, the driver will +If you specify addrs as non-zero for an interface, the driver will use the memory address given as the address of the device. This overrides si_ports. -If you specify si_ports as non-zero for an interface, the driver will +If you specify ports as non-zero for an interface, the driver will use the I/O port given as the device address. -If you specify si_irqs as non-zero for an interface, the driver will +If you specify irqs as non-zero for an interface, the driver will attempt to use the given interrupt for the device. -si_trydefaults sets whether the standard IPMI interface at 0xca2 and +trydefaults sets whether the standard IPMI interface at 0xca2 and any interfaces specified by ACPE are tried. By default, the driver tries it, set this value to zero to turn this off. +The other try... items disable discovery by their corresponding +names. These are all enabled by default, set them to zero to disable +them. The tryplatform disables openfirmware. + The next three parameters have to do with register layout. The registers used by the interfaces may not appear at successive locations and they may not be in 8-bit registers. These parameters diff --git a/Documentation/block/cfq-iosched.txt b/Documentation/block/cfq-iosched.txt index d89b4fe724d..a5eb7d19a65 100644 --- a/Documentation/block/cfq-iosched.txt +++ b/Documentation/block/cfq-iosched.txt @@ -102,6 +102,64 @@ processing of request. Therefore, increasing the value can imporve the performace although this can cause the latency of some I/O to increase due to more number of requests. +CFQ Group scheduling +==================== + +CFQ supports blkio cgroup and has "blkio." prefixed files in each +blkio cgroup directory. It is weight-based and there are four knobs +for configuration - weight[_device] and leaf_weight[_device]. +Internal cgroup nodes (the ones with children) can also have tasks in +them, so the former two configure how much proportion the cgroup as a +whole is entitled to at its parent's level while the latter two +configure how much proportion the tasks in the cgroup have compared to +its direct children. + +Another way to think about it is assuming that each internal node has +an implicit leaf child node which hosts all the tasks whose weight is +configured by leaf_weight[_device]. Let's assume a blkio hierarchy +composed of five cgroups - root, A, B, AA and AB - with the following +weights where the names represent the hierarchy. + + weight leaf_weight + root : 125 125 + A : 500 750 + B : 250 500 + AA : 500 500 + AB : 1000 500 + +root never has a parent making its weight is meaningless. For backward +compatibility, weight is always kept in sync with leaf_weight. B, AA +and AB have no child and thus its tasks have no children cgroup to +compete with. They always get 100% of what the cgroup won at the +parent level. Considering only the weights which matter, the hierarchy +looks like the following. + + root + / | \ + A B leaf + 500 250 125 + / | \ + AA AB leaf + 500 1000 750 + +If all cgroups have active IOs and competing with each other, disk +time will be distributed like the following. + +Distribution below root. The total active weight at this level is +A:500 + B:250 + C:125 = 875. + + root-leaf : 125 / 875 =~ 14% + A : 500 / 875 =~ 57% + B(-leaf) : 250 / 875 =~ 28% + +A has children and further distributes its 57% among the children and +the implicit leaf node. The total active weight at this level is +AA:500 + AB:1000 + A-leaf:750 = 2250. + + A-leaf : ( 750 / 2250) * A =~ 19% + AA(-leaf) : ( 500 / 2250) * A =~ 12% + AB(-leaf) : (1000 / 2250) * A =~ 25% + CFQ IOPS Mode for group scheduling =================================== Basic CFQ design is to provide priority based time slices. Higher priority diff --git a/Documentation/blockdev/nbd.txt b/Documentation/blockdev/nbd.txt index aeb93ffe641..271e607304d 100644 --- a/Documentation/blockdev/nbd.txt +++ b/Documentation/blockdev/nbd.txt @@ -4,43 +4,13 @@ can use a remote server as one of its block devices. So every time the client computer wants to read, e.g., /dev/nb0, it sends a request over TCP to the server, which will reply with the data read. - This can be used for stations with low disk space (or even diskless - - if you boot from floppy) to borrow disk space from another computer. - Unlike NFS, it is possible to put any filesystem on it, etc. It should - even be possible to use NBD as a root filesystem (I've never tried), - but it requires a user-level program to be in the initrd to start. - It also allows you to run block-device in user land (making server - and client physically the same computer, communicating using loopback). - - Current state: It currently works. Network block device is stable. - I originally thought that it was impossible to swap over TCP. It - turned out not to be true - swapping over TCP now works and seems - to be deadlock-free, but it requires heavy patches into Linux's - network layer. - + This can be used for stations with low disk space (or even diskless) + to borrow disk space from another computer. + Unlike NFS, it is possible to put any filesystem on it, etc. + For more information, or to download the nbd-client and nbd-server tools, go to http://nbd.sf.net/. - Howto: To setup nbd, you can simply do the following: - - First, serve a device or file from a remote server: - - nbd-server <port-number> <device-or-file-to-serve-to-client> - - e.g., - root@server1 # nbd-server 1234 /dev/sdb1 - - (serves sdb1 partition on TCP port 1234) - - Then, on the local (client) system: - - nbd-client <server-name-or-IP> <server-port-number> /dev/nb[0-n] - - e.g., - root@client1 # nbd-client server1 1234 /dev/nb0 - - (creates the nb0 device on client1) - The nbd kernel module need only be installed on the client system, as the nbd-server is completely in userspace. In fact, the nbd-server has been successfully ported to other operating diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt index b4b1fb3a83f..da272c8f44e 100644 --- a/Documentation/cgroups/blkio-controller.txt +++ b/Documentation/cgroups/blkio-controller.txt @@ -75,7 +75,7 @@ Throttling/Upper Limit policy mount -t cgroup -o blkio none /sys/fs/cgroup/blkio - Specify a bandwidth rate on particular device for root group. The format - for policy is "<major>:<minor> <byes_per_second>". + for policy is "<major>:<minor> <bytes_per_second>". echo "8:16 1048576" > /sys/fs/cgroup/blkio/blkio.throttle.read_bps_device @@ -94,13 +94,11 @@ Throttling/Upper Limit policy Hierarchical Cgroups ==================== -- Currently none of the IO control policy supports hierarchical groups. But - cgroup interface does allow creation of hierarchical cgroups and internally - IO policies treat them as flat hierarchy. +- Currently only CFQ supports hierarchical groups. For throttling, + cgroup interface does allow creation of hierarchical cgroups and + internally it treats them as flat hierarchy. - So this patch will allow creation of cgroup hierarchcy but at the backend - everything will be treated as flat. So if somebody created a hierarchy like - as follows. + If somebody created a hierarchy like as follows. root / \ @@ -108,16 +106,20 @@ Hierarchical Cgroups | test3 - CFQ and throttling will practically treat all groups at same level. + CFQ will handle the hierarchy correctly but and throttling will + practically treat all groups at same level. For details on CFQ + hierarchy support, refer to Documentation/block/cfq-iosched.txt. + Throttling will treat the hierarchy as if it looks like the + following. pivot / / \ \ root test1 test2 test3 - Down the line we can implement hierarchical accounting/control support - and also introduce a new cgroup file "use_hierarchy" which will control - whether cgroup hierarchy is viewed as flat or hierarchical by the policy.. - This is how memory controller also has implemented the things. + Nesting cgroups, while allowed, isn't officially supported and blkio + genereates warning when cgroups nest. Once throttling implements + hierarchy support, hierarchy will be supported and the warning will + be removed. Various user visible config options =================================== @@ -172,6 +174,12 @@ Proportional weight policy files dev weight 8:16 300 +- blkio.leaf_weight[_device] + - Equivalents of blkio.weight[_device] for the purpose of + deciding how much weight tasks in the given cgroup has while + competing with the cgroup's child cgroups. For details, + please refer to Documentation/block/cfq-iosched.txt. + - blkio.time - disk time allocated to cgroup per device in milliseconds. First two fields specify the major and minor number of the device and @@ -279,6 +287,11 @@ Proportional weight policy files and minor number of the device and third field specifies the number of times a group was dequeued from a particular device. +- blkio.*_recursive + - Recursive version of various stats. These files show the + same information as their non-recursive counterparts but + include stats from all the descendant cgroups. + Throttling/Upper limit policy files ----------------------------------- - blkio.throttle.read_bps_device diff --git a/Documentation/coccinelle.txt b/Documentation/coccinelle.txt index cf44eb6499b..dffa2d620d6 100644 --- a/Documentation/coccinelle.txt +++ b/Documentation/coccinelle.txt @@ -87,6 +87,10 @@ As any static code analyzer, Coccinelle produces false positives. Thus, reports must be carefully checked, and patches reviewed. +To enable verbose messages set the V= variable, for example: + + make coccicheck MODE=report V=1 + Using Coccinelle with a single semantic patch ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ diff --git a/Documentation/kbuild/kconfig-language.txt b/Documentation/kbuild/kconfig-language.txt index a686f9cd69c..c858f8419eb 100644 --- a/Documentation/kbuild/kconfig-language.txt +++ b/Documentation/kbuild/kconfig-language.txt @@ -388,26 +388,3 @@ config FOO depends on BAR && m limits FOO to module (=m) or disabled (=n). - -Kconfig symbol existence -~~~~~~~~~~~~~~~~~~~~~~~~ -The following two methods produce the same kconfig symbol dependencies -but differ greatly in kconfig symbol existence (production) in the -generated config file. - -case 1: - -config FOO - tristate "about foo" - depends on BAR - -vs. case 2: - -if BAR -config FOO - tristate "about foo" -endif - -In case 1, the symbol FOO will always exist in the config file (given -no other dependencies). In case 2, the symbol FOO will only exist in -the config file if BAR is enabled. diff --git a/Documentation/kbuild/kconfig.txt b/Documentation/kbuild/kconfig.txt index a09f1a6a830..b8b77bbc784 100644 --- a/Documentation/kbuild/kconfig.txt +++ b/Documentation/kbuild/kconfig.txt @@ -46,6 +46,12 @@ KCONFIG_OVERWRITECONFIG If you set KCONFIG_OVERWRITECONFIG in the environment, Kconfig will not break symlinks when .config is a symlink to somewhere else. +CONFIG_ +-------------------------------------------------- +If you set CONFIG_ in the environment, Kconfig will prefix all symbols +with its value when saving the configuration, instead of using the default, +"CONFIG_". + ______________________________________________________________________ Environment variables for '{allyes/allmod/allno/rand}config' diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 1da94654877..e567af39ee3 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -564,6 +564,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted. UART at the specified I/O port or MMIO address, switching to the matching ttyS device later. The options are the same as for ttyS, above. + hvc<n> Use the hypervisor console device <n>. This is for + both Xen and PowerPC hypervisors. If the device connected to the port is not a TTY but a braille device, prepend "brl," before the device type, for instance @@ -757,6 +759,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. earlyprintk= [X86,SH,BLACKFIN] earlyprintk=vga + earlyprintk=xen earlyprintk=serial[,ttySn[,baudrate]] earlyprintk=ttySn[,baudrate] earlyprintk=dbgp[debugController#] @@ -774,6 +777,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted. The VGA output is eventually overwritten by the real console. + The xen output can only be used by Xen PV guests. + ekgdboc= [X86,KGDB] Allow early kernel console debugging ekgdboc=kbd |