Talk:Hardware Power Domains: Difference between revisions

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(S2 is uninteresting)
 
(C1 test)
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== Power Domain Discussion ==
= Power Domain Discussion =


> No support for optional ACPI Sleep state S2
== No support for optional ACPI Sleep state S2 ==


* S2 is uninteresting. IMHO - its a vague state literally defined as "higher latency then S1 but lower latency then S3". Not sure if your itention here is to mention that S2 *should*
* S2 is uninteresting. IMHO - its a vague state literally defined as "higher latency then S1 but lower latency then S3". Not sure if your itention here is to mention that S2 *should*
be supported, or just commenting that it isn't. - [[User:JordanCrouse|JordanCrouse]] ([[User talk:JordanCrouse|Talk to me!]]) 18:58, 12 September 2006 (EDT)
be supported, or just commenting that it isn't. - [[User:JordanCrouse|JordanCrouse]] ([[User talk:JordanCrouse|Talk to me!]]) 18:58, 12 September 2006 (EDT)

== C1 Test ==

This confused me for a second - what you're talking about is really more of a poor man's S1 - turning off pratically everything we can, turn off the PIT,
and then enable wakeup devices and go to a hlt. A more correct name might be low-latency S1, because it will be slower then a C state transition (obivously) but it should be faster then a S1 transition.

This is quite similar to a tickless system, except that we turn off more devices. The only question is - how quickly can we turn off and turn on the un-needed devices, and does that latency fit within the average idle timesice of a nominally busy kernel? I believe that we can measure the average length between timeouts in the kernel with Systemtap - that would be useful information
to have. If we can make this all fit - it would be a heck of a cool thing. - [[User:JordanCrouse|JordanCrouse]] ([[User talk:JordanCrouse|Talk to me!]]) 19:16, 12 September 2006 (EDT)

Revision as of 23:16, 12 September 2006

Power Domain Discussion

No support for optional ACPI Sleep state S2

  • S2 is uninteresting. IMHO - its a vague state literally defined as "higher latency then S1 but lower latency then S3". Not sure if your itention here is to mention that S2 *should*

be supported, or just commenting that it isn't. - JordanCrouse (Talk to me!) 18:58, 12 September 2006 (EDT)

C1 Test

This confused me for a second - what you're talking about is really more of a poor man's S1 - turning off pratically everything we can, turn off the PIT, and then enable wakeup devices and go to a hlt. A more correct name might be low-latency S1, because it will be slower then a C state transition (obivously) but it should be faster then a S1 transition.

This is quite similar to a tickless system, except that we turn off more devices. The only question is - how quickly can we turn off and turn on the un-needed devices, and does that latency fit within the average idle timesice of a nominally busy kernel? I believe that we can measure the average length between timeouts in the kernel with Systemtap - that would be useful information to have. If we can make this all fit - it would be a heck of a cool thing. - JordanCrouse (Talk to me!) 19:16, 12 September 2006 (EDT)