Prefs presets

A proposal for simplifying the prefs interface by providing a few "presets" - named preference sets - as the default interface.

Note: another design doc proposes more sweeping changes. This doc doesn't propose changing the preferences, just the interface.

Initially this would be in the web interface. Eventually the Manager should provide the same interface.

Proposed presets

Max computing

Allow computing on all CPUs and GPUs, all the time. Fan noise and power usage not issues.

Standard

Be inaudible and invisible (in particular, don't cause fans to go on high speed). Given that, compute as much as possible.

To implement this properly we need detection of fan speeds (system, CPU, GPU).

Need to not run VMs while busy (or maybe keep 1 core free), until VBox fixes priority issue.

Energy-saver

Compute as energy-efficiently as possible.

To implement this properly we need to look at Peter Hannape's work and figure out how to put the CPU into the mode that maximizes FLOPS/watt.

Don't compute while idle; let the computer go into low-power mode or turn off

Proposed values

	Max	Standard	Green
use at most X% of CPUs	100	85	60
use at most X% of CPU time	100	100	100
suspend when on battery	yes	yes	yes
suspend when computer in use	no	no	no
suspend GPU when computer in use	no	yes	yes
in use means no input in X min	3	3	3
suspend when no input in X min	---	---	10
suspend when non-BOINC CPU above	---	50	50
store at least X days of work	.1	.1	.1
store an extra X days of work	.5	.5	.5
switch tasks every X min	60	60	60
request checkpoint every X sec	180	180	180
use no more than XGB disk	---	---	---
leave at least XGB free	1	1	1
use no more than X% total disk	90	90	90
when in use, use < X% RAM	70	50	50
when not in use, use < X% RAM	90	90	90
leave non-GPU tasks in mem	yes	no	no
use at most X% swap file	75	75	75
download rate limit kb/sec	---	---	---
upload rate limit kb/sec	---	---	---

Implementation

If a user selects a preset, we store the preset name (max, standard, green) in user.global_prefs, rather than the prefs themselves. Example:

<global_preferences>
<preset>green</preset>
<venue name="home">
<preset>max</preset>
</venue>
</global_preferences>

The scheduler sends the corresponding prefs in its reply. This lets us change/extend the meanings of the standard presets, and lets each project define its own presets if it wants.

Initial implementation: for simplicity, support only presets. Enable this by PREFS_PRESETS in project.inc.

Presets will be stored in a file "prefs_presets.xml" in the project directory, with the structure

<presets>
   <preset>
      <name>Green</name>
      <description>Limit power consumption</description>
      <prefs>
<![CDATA[
<max_ncpus_pct>25</max_ncpus_pct>
<cpu_usage_limit>100</cpu_usage_limit>
...
]]>
      </prefs>
   </preset>
   ...
</presets>

Scheduler: when sending global prefs, check if it's a preset and expand accordingly. Also send the preset name in case we want to show it in the Manager.