diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/DocBook/device-drivers.tmpl | 1 | ||||
| -rw-r--r-- | Documentation/DocBook/kernel-api.tmpl | 1 | ||||
| -rw-r--r-- | Documentation/DocBook/kernel-locking.tmpl | 6 | ||||
| -rw-r--r-- | Documentation/DocBook/tracepoint.tmpl | 5 | ||||
| -rw-r--r-- | Documentation/block/cfq-iosched.txt | 45 | ||||
| -rw-r--r-- | Documentation/cgroups/blkio-controller.txt | 28 | ||||
| -rw-r--r-- | Documentation/gpio.txt | 22 | ||||
| -rw-r--r-- | Documentation/kernel-doc-nano-HOWTO.txt | 5 | ||||
| -rw-r--r-- | Documentation/kernel-parameters.txt | 17 | ||||
| -rw-r--r-- | Documentation/mutex-design.txt | 3 |
10 files changed, 115 insertions, 18 deletions
diff --git a/Documentation/DocBook/device-drivers.tmpl b/Documentation/DocBook/device-drivers.tmpl index ecd35e9d4410..feca0758391e 100644 --- a/Documentation/DocBook/device-drivers.tmpl +++ b/Documentation/DocBook/device-drivers.tmpl @@ -46,7 +46,6 @@ <sect1><title>Atomic and pointer manipulation</title> !Iarch/x86/include/asm/atomic.h -!Iarch/x86/include/asm/unaligned.h </sect1> <sect1><title>Delaying, scheduling, and timer routines</title> diff --git a/Documentation/DocBook/kernel-api.tmpl b/Documentation/DocBook/kernel-api.tmpl index a20c6f6fffc3..6899f471fb15 100644 --- a/Documentation/DocBook/kernel-api.tmpl +++ b/Documentation/DocBook/kernel-api.tmpl @@ -57,7 +57,6 @@ </para> <sect1><title>String Conversions</title> -!Ilib/vsprintf.c !Elib/vsprintf.c </sect1> <sect1><title>String Manipulation</title> diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl index 0b1a3f97f285..a0d479d1e1dd 100644 --- a/Documentation/DocBook/kernel-locking.tmpl +++ b/Documentation/DocBook/kernel-locking.tmpl @@ -1961,6 +1961,12 @@ machines due to caching. </sect1> </chapter> + <chapter id="apiref"> + <title>Mutex API reference</title> +!Iinclude/linux/mutex.h +!Ekernel/mutex.c + </chapter> + <chapter id="references"> <title>Further reading</title> diff --git a/Documentation/DocBook/tracepoint.tmpl b/Documentation/DocBook/tracepoint.tmpl index e8473eae2a20..b57a9ede3224 100644 --- a/Documentation/DocBook/tracepoint.tmpl +++ b/Documentation/DocBook/tracepoint.tmpl @@ -104,4 +104,9 @@ <title>Block IO</title> !Iinclude/trace/events/block.h </chapter> + + <chapter id="workqueue"> + <title>Workqueue</title> +!Iinclude/trace/events/workqueue.h + </chapter> </book> diff --git a/Documentation/block/cfq-iosched.txt b/Documentation/block/cfq-iosched.txt new file mode 100644 index 000000000000..e578feed6d81 --- /dev/null +++ b/Documentation/block/cfq-iosched.txt @@ -0,0 +1,45 @@ +CFQ ioscheduler tunables +======================== + +slice_idle +---------- +This specifies how long CFQ should idle for next request on certain cfq queues +(for sequential workloads) and service trees (for random workloads) before +queue is expired and CFQ selects next queue to dispatch from. + +By default slice_idle is a non-zero value. That means by default we idle on +queues/service trees. This can be very helpful on highly seeky media like +single spindle SATA/SAS disks where we can cut down on overall number of +seeks and see improved throughput. + +Setting slice_idle to 0 will remove all the idling on queues/service tree +level and one should see an overall improved throughput on faster storage +devices like multiple SATA/SAS disks in hardware RAID configuration. The down +side is that isolation provided from WRITES also goes down and notion of +IO priority becomes weaker. + +So depending on storage and workload, it might be useful to set slice_idle=0. +In general I think for SATA/SAS disks and software RAID of SATA/SAS disks +keeping slice_idle enabled should be useful. For any configurations where +there are multiple spindles behind single LUN (Host based hardware RAID +controller or for storage arrays), setting slice_idle=0 might end up in better +throughput and acceptable latencies. + +CFQ IOPS Mode for group scheduling +=================================== +Basic CFQ design is to provide priority based time slices. Higher priority +process gets bigger time slice and lower priority process gets smaller time +slice. Measuring time becomes harder if storage is fast and supports NCQ and +it would be better to dispatch multiple requests from multiple cfq queues in +request queue at a time. In such scenario, it is not possible to measure time +consumed by single queue accurately. + +What is possible though is to measure number of requests dispatched from a +single queue and also allow dispatch from multiple cfq queue at the same time. +This effectively becomes the fairness in terms of IOPS (IO operations per +second). + +If one sets slice_idle=0 and if storage supports NCQ, CFQ internally switches +to IOPS mode and starts providing fairness in terms of number of requests +dispatched. Note that this mode switching takes effect only for group +scheduling. For non-cgroup users nothing should change. diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt index 48e0b21b0059..6919d62591d9 100644 --- a/Documentation/cgroups/blkio-controller.txt +++ b/Documentation/cgroups/blkio-controller.txt @@ -217,6 +217,7 @@ Details of cgroup files CFQ sysfs tunable ================= /sys/block/<disk>/queue/iosched/group_isolation +----------------------------------------------- If group_isolation=1, it provides stronger isolation between groups at the expense of throughput. By default group_isolation is 0. In general that @@ -243,6 +244,33 @@ By default one should run with group_isolation=0. If that is not sufficient and one wants stronger isolation between groups, then set group_isolation=1 but this will come at cost of reduced throughput. +/sys/block/<disk>/queue/iosched/slice_idle +------------------------------------------ +On a faster hardware CFQ can be slow, especially with sequential workload. +This happens because CFQ idles on a single queue and single queue might not +drive deeper request queue depths to keep the storage busy. In such scenarios +one can try setting slice_idle=0 and that would switch CFQ to IOPS +(IO operations per second) mode on NCQ supporting hardware. + +That means CFQ will not idle between cfq queues of a cfq group and hence be +able to driver higher queue depth and achieve better throughput. That also +means that cfq provides fairness among groups in terms of IOPS and not in +terms of disk time. + +/sys/block/<disk>/queue/iosched/group_idle +------------------------------------------ +If one disables idling on individual cfq queues and cfq service trees by +setting slice_idle=0, group_idle kicks in. That means CFQ will still idle +on the group in an attempt to provide fairness among groups. + +By default group_idle is same as slice_idle and does not do anything if +slice_idle is enabled. + +One can experience an overall throughput drop if you have created multiple +groups and put applications in that group which are not driving enough +IO to keep disk busy. In that case set group_idle=0, and CFQ will not idle +on individual groups and throughput should improve. + What works ========== - Currently only sync IO queues are support. All the buffered writes are diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt index d96a6dba5748..9633da01ff46 100644 --- a/Documentation/gpio.txt +++ b/Documentation/gpio.txt @@ -109,17 +109,19 @@ use numbers 2000-2063 to identify GPIOs in a bank of I2C GPIO expanders. If you want to initialize a structure with an invalid GPIO number, use some negative number (perhaps "-EINVAL"); that will never be valid. To -test if a number could reference a GPIO, you may use this predicate: +test if such number from such a structure could reference a GPIO, you +may use this predicate: int gpio_is_valid(int number); A number that's not valid will be rejected by calls which may request or free GPIOs (see below). Other numbers may also be rejected; for -example, a number might be valid but unused on a given board. - -Whether a platform supports multiple GPIO controllers is currently a -platform-specific implementation issue. +example, a number might be valid but temporarily unused on a given board. +Whether a platform supports multiple GPIO controllers is a platform-specific +implementation issue, as are whether that support can leave "holes" in the space +of GPIO numbers, and whether new controllers can be added at runtime. Such issues +can affect things including whether adjacent GPIO numbers are both valid. Using GPIOs ----------- @@ -480,12 +482,16 @@ To support this framework, a platform's Kconfig will "select" either ARCH_REQUIRE_GPIOLIB or ARCH_WANT_OPTIONAL_GPIOLIB and arrange that its <asm/gpio.h> includes <asm-generic/gpio.h> and defines three functions: gpio_get_value(), gpio_set_value(), and gpio_cansleep(). -They may also want to provide a custom value for ARCH_NR_GPIOS. -ARCH_REQUIRE_GPIOLIB means that the gpio-lib code will always get compiled +It may also provide a custom value for ARCH_NR_GPIOS, so that it better +reflects the number of GPIOs in actual use on that platform, without +wasting static table space. (It should count both built-in/SoC GPIOs and +also ones on GPIO expanders. + +ARCH_REQUIRE_GPIOLIB means that the gpiolib code will always get compiled into the kernel on that architecture. -ARCH_WANT_OPTIONAL_GPIOLIB means the gpio-lib code defaults to off and the user +ARCH_WANT_OPTIONAL_GPIOLIB means the gpiolib code defaults to off and the user can enable it and build it into the kernel optionally. If neither of these options are selected, the platform does not support diff --git a/Documentation/kernel-doc-nano-HOWTO.txt b/Documentation/kernel-doc-nano-HOWTO.txt index 27a52b35d55b..3d8a97747f77 100644 --- a/Documentation/kernel-doc-nano-HOWTO.txt +++ b/Documentation/kernel-doc-nano-HOWTO.txt @@ -345,5 +345,10 @@ documentation, in <filename>, for the functions listed. section titled <section title> from <filename>. Spaces are allowed in <section title>; do not quote the <section title>. +!C<filename> is replaced by nothing, but makes the tools check that +all DOC: sections and documented functions, symbols, etc. are used. +This makes sense to use when you use !F/!P only and want to verify +that all documentation is included. + Tim. */ <twaugh@redhat.com> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index f084af0cb8e0..8dd7248508a9 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1974,15 +1974,18 @@ and is between 256 and 4096 characters. It is defined in the file force Enable ASPM even on devices that claim not to support it. WARNING: Forcing ASPM on may cause system lockups. + pcie_ports= [PCIE] PCIe ports handling: + auto Ask the BIOS whether or not to use native PCIe services + associated with PCIe ports (PME, hot-plug, AER). Use + them only if that is allowed by the BIOS. + native Use native PCIe services associated with PCIe ports + unconditionally. + compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe + ports driver. + pcie_pme= [PCIE,PM] Native PCIe PME signaling options: - Format: {auto|force}[,nomsi] - auto Use native PCIe PME signaling if the BIOS allows the - kernel to control PCIe config registers of root ports. - force Use native PCIe PME signaling even if the BIOS refuses - to allow the kernel to control the relevant PCIe config - registers. nomsi Do not use MSI for native PCIe PME signaling (this makes - all PCIe root ports use INTx for everything). + all PCIe root ports use INTx for all services). pcmv= [HW,PCMCIA] BadgePAD 4 diff --git a/Documentation/mutex-design.txt b/Documentation/mutex-design.txt index c91ccc0720fa..38c10fd7f411 100644 --- a/Documentation/mutex-design.txt +++ b/Documentation/mutex-design.txt @@ -9,7 +9,7 @@ firstly, there's nothing wrong with semaphores. But if the simpler mutex semantics are sufficient for your code, then there are a couple of advantages of mutexes: - - 'struct mutex' is smaller on most architectures: .e.g on x86, + - 'struct mutex' is smaller on most architectures: E.g. on x86, 'struct semaphore' is 20 bytes, 'struct mutex' is 16 bytes. A smaller structure size means less RAM footprint, and better CPU-cache utilization. @@ -136,3 +136,4 @@ the APIs of 'struct mutex' have been streamlined: void mutex_lock_nested(struct mutex *lock, unsigned int subclass); int mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass); + int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock); |