Few notes from openSUSE Conference 2011

osc11/Baumann - Enterprise Cloud Solution with Open Stack.asciidoc

@@ -0,0 +1,33 @@
+Enterprise Cloud Solution with Open Stack
+=========================================
+:presenter:  Christian Baumann
+:presented:  9/11/2011
+:type:       talk
+:conference: osc2011
+
+One of the open source cloud solutions. Aim is to be simple and massively
+scalable. Apache 2.0 licence, hosted on launchpad.
+
+Tree main project:
+* Compute (Nova)
+** Computing part
+** Manages creation and deployment of virtual machines
+** EC2 and OpenStack API
+* Image Registration (Glance)
+** registers virtual disk files
+** focused on scalability
+** outside access via REST
+** can use Swift as a backend
+* Object Storage (Swift)
+** no block devices
+** REST interface
+** runs on normal machines
+** several components
+*** proxy servers - connecting stuff
+*** storage servers - storing data
+*** tool servers - maintenance
+** hardware is divided into availability zones
+
+Users management is also possible, based on private/public keys. Several roles
+and projects can be defined and permissions granularized.
+

osc11/README.asciidoc

@@ -0,0 +1,8 @@
+openSUSE Conference 2011
+========================
+
+The third openSUSE Conference took place in Nürnberg, Germany from 11. to 14. September 2011 with the motto RWX³
+
+All openSUSE- and Free Software enthusiasts were invited to come together at this conference to learn, hack and have a lot of fun.
+
+There were Talks, Workshops and Birds of a Feather sessions on a large variety of topics.

osc11/Wysocki - Linux Kernel Power Management On Embedded Systems.asciidoc

@@ -0,0 +1,64 @@
+Linux Kernel Power Management on Embedded Systems
+=================================================
+:presenter:  Wysocki, Rafael
+:presented:  9/14/2011
+:type:       talk
+:conference: osc2011
+
+Embedded
+--------
+
+* Small, SoC, low power consumption
+* typically ARM
+* devices are not discoverable, but memory mapped and fixed
+* more controllable hardware
+* no BIOS
+* everything is uninitialized in the beginning, firmware initializes some things and loads the kernel - popular one is U-Boot
+* clocks can be manipulated
+* different power domains (sets of devices connected to same power line)
+* interrupts from the sleep states
+* interfaces for voltage/frequency scaling
+* multiple CPU cores that can be even different architecture
+* various caches
+
+CPUidle
+~~~~~~~
+
+CPU scheduler knows, when CPU is or will be idle, we can use it for power
+saving. Some systems have for example low performance cores and high
+performance cores. During low load, low performance cores are used and during
+high load, more powerful ones are waked up. Switching off some cores might not
+be easy, as CPUs can be part of the same power domain as some other crucial
+system (for example IO controller, DMA, cache, ...). Before going to sleep, it
+is good to know, how long does it take to go to the sleep, to wake up and how
+much energy it will take. Power Break Even Time - shortest time it make sense
+to go to the sleep for.
+
+CPUfreq
+~~~~~~~
+
+Scale CPU frequency and voltage to drain less power. Possible problem is, that
+CPU clock might be shared with some other devices. Clocks doesn't have to be
+changeable every time, device might need to finish operation first. There also
+might be some voltage and clock requirements from other connected devices.
+
+PM
+~~
+
+Every subsystem has callbacks for shutting down and waking up. But these can be
+overrided by power domain callbacks `dev_pm_domain` (newly added in 3.0
+kernel). Power domain handling has been implementer in 3.1.
+
+Sleep States
+~~~~~~~~~~~~
+
+* Android uses system suspend for power saving
+* Wakeup from deep low-power states may require special signaling
+* Difference from power off is preservation of RAM
+* Some systems requires periodic wake ups
+* state features
+** user space is frozen
+** reduced energy consumption
+** user space should be able to say how to wake
+** enterable any time
+