From 6d6ac1c1a3d4f95953aa3b085e8f16692d3a7179 Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Mon, 23 Aug 2010 12:25:29 +0200 Subject: cfq-iosched: Documentation help for new tunables Some documentation to provide help with tunables. Signed-off-by: Vivek Goyal Acked-by: Jeff Moyer Signed-off-by: Jens Axboe --- Documentation/block/cfq-iosched.txt | 45 ++++++++++++++++++++++++++++++ Documentation/cgroups/blkio-controller.txt | 28 +++++++++++++++++++ 2 files changed, 73 insertions(+) create mode 100644 Documentation/block/cfq-iosched.txt (limited to 'Documentation') diff --git a/Documentation/block/cfq-iosched.txt b/Documentation/block/cfq-iosched.txt new file mode 100644 index 0000000..e578fee --- /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 48e0b21..6919d62 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//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//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//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 -- cgit v1.1 From 79dd9182db2072d63ccf160bb9a3463b1c952723 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Sat, 21 Aug 2010 01:51:44 +0200 Subject: PCI: PCIe: Introduce commad line switch for disabling port services Introduce kernel command line switch pcie_ports= allowing one to disable all of the native PCIe port services, so that PCIe ports are treated like PCI-to-PCI bridges. Signed-off-by: Rafael J. Wysocki Signed-off-by: Jesse Barnes --- Documentation/kernel-parameters.txt | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'Documentation') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 873b680..b9008fc 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2042,6 +2042,10 @@ 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: + 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 -- cgit v1.1 From 28eb5f274a305bf3a13b2c80c4804d4515d05c64 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Sat, 21 Aug 2010 22:02:38 +0200 Subject: PCI: PCIe: Ask BIOS for control of all native services at once After commit 852972acff8f10f3a15679be2059bb94916cba5d (ACPI: Disable ASPM if the platform won't provide _OSC control for PCIe) control of the PCIe Capability Structure is unconditionally requested by acpi_pci_root_add(), which in principle may cause problems to happen in two ways. First, the BIOS may refuse to give control of the PCIe Capability Structure if it is not asked for any of the _OSC features depending on it at the same time. Second, the BIOS may assume that control of the _OSC features depending on the PCIe Capability Structure will be requested in the future and may behave incorrectly if that doesn't happen. For this reason, control of the PCIe Capability Structure should always be requested along with control of any other _OSC features that may depend on it (ie. PCIe native PME, PCIe native hot-plug, PCIe AER). Rework the PCIe port driver so that (1) it checks which native PCIe port services can be enabled, according to the BIOS, and (2) it requests control of all these services simultaneously. In particular, this causes pcie_portdrv_probe() to fail if the BIOS refuses to grant control of the PCIe Capability Structure, which means that no native PCIe port services can be enabled for the PCIe Root Complex the given port belongs to. If that happens, ASPM is disabled to avoid problems with mishandling it by the part of the PCIe hierarchy for which control of the PCIe Capability Structure has not been received. Make it possible to override this behavior using 'pcie_ports=native' (use the PCIe native services regardless of the BIOS response to the control request), or 'pcie_ports=compat' (do not use the PCIe native services at all). Accordingly, rework the existing PCIe port service drivers so that they don't request control of the services directly. Signed-off-by: Rafael J. Wysocki Signed-off-by: Jesse Barnes --- Documentation/kernel-parameters.txt | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) (limited to 'Documentation') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index b9008fc..8f126e8 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2043,18 +2043,17 @@ and is between 256 and 4096 characters. It is defined in the file 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 -- cgit v1.1 From 7c38875a0d0a9b90eee66be79e36995c86acc70c Mon Sep 17 00:00:00 2001 From: Jason Baron Date: Thu, 26 Aug 2010 10:35:43 -0400 Subject: workqueue: Add a workqueue chapter to the tracepoint docbook Add a workqueue chapter to the traceopint docbook. Current book is at: http://www.kernel.org/doc/htmldocs/tracepoint/ Signed-off-by: Jason Baron Signed-off-by: Tejun Heo --- Documentation/DocBook/tracepoint.tmpl | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'Documentation') diff --git a/Documentation/DocBook/tracepoint.tmpl b/Documentation/DocBook/tracepoint.tmpl index e8473ea..b57a9ed 100644 --- a/Documentation/DocBook/tracepoint.tmpl +++ b/Documentation/DocBook/tracepoint.tmpl @@ -104,4 +104,9 @@ Block IO !Iinclude/trace/events/block.h + + + Workqueue +!Iinclude/trace/events/workqueue.h + -- cgit v1.1 From 048e78a5bc22c27410cb5ca9680c3c7ac400607f Mon Sep 17 00:00:00 2001 From: David Henningsson Date: Thu, 2 Sep 2010 08:35:47 +0200 Subject: ALSA: hda - Add a new hp-laptop model for Conexant 5066, tested on HP G60 This new model adds the following functionality to HP G60: - Automute of internal speakers - Autoswitch of internal/external mics - Remove SPDIF not physically present BugLink: http://launchpad.net/bugs/587388 Cc: stable@kernel.org Signed-off-by: David Henningsson Signed-off-by: Takashi Iwai --- Documentation/sound/alsa/HD-Audio-Models.txt | 1 + 1 file changed, 1 insertion(+) (limited to 'Documentation') diff --git a/Documentation/sound/alsa/HD-Audio-Models.txt b/Documentation/sound/alsa/HD-Audio-Models.txt index ce46fa1..37c6aad 100644 --- a/Documentation/sound/alsa/HD-Audio-Models.txt +++ b/Documentation/sound/alsa/HD-Audio-Models.txt @@ -296,6 +296,7 @@ Conexant 5051 Conexant 5066 ============= laptop Basic Laptop config (default) + hp-laptop HP laptops, e g G60 dell-laptop Dell laptops dell-vostro Dell Vostro olpc-xo-1_5 OLPC XO 1.5 -- cgit v1.1 From ef5dc121d5a0bb1fa477c5395277259f07d318a3 Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Thu, 2 Sep 2010 15:48:16 -0700 Subject: mutex: Fix annotations to include it in kernel-locking docbook Fix kernel-doc notation in linux/mutex.h and kernel/mutex.c, then add these 2 files to the kernel-locking docbook as the Mutex API reference chapter. Add one API function to mutex-design.txt and correct a typo in that file. Signed-off-by: Randy Dunlap Cc: Rusty Russell LKML-Reference: <20100902154816.6cc2f9ad.randy.dunlap@oracle.com> Signed-off-by: Ingo Molnar --- Documentation/DocBook/kernel-locking.tmpl | 6 ++++++ Documentation/mutex-design.txt | 3 ++- 2 files changed, 8 insertions(+), 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl index 0b1a3f9..a0d479d 100644 --- a/Documentation/DocBook/kernel-locking.tmpl +++ b/Documentation/DocBook/kernel-locking.tmpl @@ -1961,6 +1961,12 @@ machines due to caching. + + Mutex API reference +!Iinclude/linux/mutex.h +!Ekernel/mutex.c + + Further reading diff --git a/Documentation/mutex-design.txt b/Documentation/mutex-design.txt index c91ccc0..38c10fd 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); -- cgit v1.1 From c956126c137d97acb6f4d56fa9572d0bcc84e4ed Mon Sep 17 00:00:00 2001 From: David Brownell Date: Thu, 9 Sep 2010 16:38:03 -0700 Subject: gpio: doc updates There's been some recent confusion about error checking GPIO numbers. briefly, it should be handled mostly during setup, when gpio_request() is called, and NEVER by expectig gpio_is_valid to report more than never-usable GPIO numbers. [akpm@linux-foundation.org: terminate unterminated comment] Signed-off-by: David Brownell Cc: Eric Miao" Cc: "Ryan Mallon" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/gpio.txt | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) (limited to 'Documentation') diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt index d96a6db..9633da0 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 includes 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 -- cgit v1.1 From eda603f6cdba4b14dbf80531fab2fe545232e7a0 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Sat, 11 Sep 2010 15:55:22 -0700 Subject: docbook: warn on unused doc entries When you don't use !E or !I but only !F, then it's very easy to miss including some functions, structs etc. in documentation. To help finding which ones were missed, allow printing out the unused ones as warnings. For example, using this on mac80211 yields a lot of warnings like this: Warning: didn't use docs for DOC: mac80211 workqueue Warning: didn't use docs for ieee80211_max_queues Warning: didn't use docs for ieee80211_bss_change Warning: didn't use docs for ieee80211_bss_conf when generating the documentation for it. Signed-off-by: Johannes Berg Signed-off-by: Randy Dunlap Signed-off-by: Linus Torvalds --- Documentation/kernel-doc-nano-HOWTO.txt | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'Documentation') diff --git a/Documentation/kernel-doc-nano-HOWTO.txt b/Documentation/kernel-doc-nano-HOWTO.txt index 27a52b3..3d8a977 100644 --- a/Documentation/kernel-doc-nano-HOWTO.txt +++ b/Documentation/kernel-doc-nano-HOWTO.txt @@ -345,5 +345,10 @@ documentation, in , for the functions listed. section titled
from . Spaces are allowed in
; do not quote the
. +!C 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. */ -- cgit v1.1 From 39d709392ffc1d05f825191b07b7d865d434f282 Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Sat, 11 Sep 2010 15:55:26 -0700 Subject: docbook: skip files with no docs since they generate scary warnings Fix docbook templates that reference files that do not contain the expected kernel-doc notation. Fixes these warnings: Warning(arch/x86/include/asm/unaligned.h): no structured comments found Warning(lib/vsprintf.c): no structured comments found These cause errors in the generated html output, like below, so drop these lines. Name arch/x86/include/asm/unaligned.h - Document generation inconsistency Oops Warning The template for this document tried to insert the structured comment from the file arch/x86/include/asm/unaligned.h at this point, but none was found. This dummy section is inserted to allow generation to continue. Signed-off-by: Randy Dunlap Signed-off-by: Linus Torvalds --- Documentation/DocBook/device-drivers.tmpl | 1 - Documentation/DocBook/kernel-api.tmpl | 1 - 2 files changed, 2 deletions(-) (limited to 'Documentation') diff --git a/Documentation/DocBook/device-drivers.tmpl b/Documentation/DocBook/device-drivers.tmpl index ecd35e9..feca075 100644 --- a/Documentation/DocBook/device-drivers.tmpl +++ b/Documentation/DocBook/device-drivers.tmpl @@ -46,7 +46,6 @@ Atomic and pointer manipulation !Iarch/x86/include/asm/atomic.h -!Iarch/x86/include/asm/unaligned.h Delaying, scheduling, and timer routines diff --git a/Documentation/DocBook/kernel-api.tmpl b/Documentation/DocBook/kernel-api.tmpl index a20c6f6..6899f47 100644 --- a/Documentation/DocBook/kernel-api.tmpl +++ b/Documentation/DocBook/kernel-api.tmpl @@ -57,7 +57,6 @@ String Conversions -!Ilib/vsprintf.c !Elib/vsprintf.c String Manipulation -- cgit v1.1