{"id":1296,"date":"2007-05-08T17:24:23","date_gmt":"2007-05-08T15:24:23","guid":{"rendered":"http:\/\/vizZzion.org\/blog\/2007\/05\/powermanagement-improvements\/"},"modified":"2007-05-08T17:24:23","modified_gmt":"2007-05-08T15:24:23","slug":"powermanagement-improvements","status":"publish","type":"post","link":"https:\/\/vizZzion.org\/blog\/2007\/05\/powermanagement-improvements\/","title":{"rendered":"Powermanagement improvements."},"content":{"rendered":"<p>\n\t\tThere&#8217;s quite some discussion about powermanagement here at the Ubuntu<br \/>\n\t\tDevelopers Summit in sunny Sevilla. There are quite some Intel people around<br \/>\n\t\there, providing lots of insight in powermanagement on a hardware and driver<br \/>\n\t\tlevel. Here&#8217;s a couple of points that have come up.<\/p>\n<ul>\n<li>\n\t\t\t\tFirst, the good news. KDE is in a pretty good shape when it comes to<br \/>\n\t\t<strong>sleeping applications<\/strong>. Applications using timers can wake up<br \/>\n\t\tthe CPU from sleep states (or even prevent sleeping in the worst case). The CPU<br \/>\n\t\tsleep states (usually named C-states) greatly reduce CPU power draining. The<br \/>\n\t\tworst offenders are currently kopete (responsible for 40% of the wakeups on a<br \/>\n\t\tFedora test system) and HAL polling the CD-ROM drive every two seconds. Will<br \/>\n\t\tStephenson told me that kopete in KDE4 is fixed already, and that fixing the<br \/>\n\t\tKDE3 version is on his radar. This makes KDE even more battery friendly.<br \/>\n\t\tGenerally, KDE&#8217;s technical design makes it rather easy to fix those issues<br \/>\n\t\tsystem-wide. Kudos to the people working on this!\n\t\t\t<\/li>\n<li>\n\t\t\t\t<strong>Tickless kernel<\/strong>. The new <a\n\t\thref=\"http:\/\/kerneltrap.org\/node\/6750\">dynticks and hi-res timers<\/a> make a<br \/>\n\t\t*huge* difference. Ben Collins mentioned 30 &#8211; 40 minutes of extra battery life<br \/>\n\t\twith dynticks and hi-res timers enabled. This stuff is new in 2.6.21, and<br \/>\n\t\talready in the Gutsy kernel. dynticks also make it possible for the CPU to sleep<br \/>\n\t\tmuch more. Another thing that&#8217;s important in that respect is HPET, basically<br \/>\n\t\tdoing something similar, but less effective. Every bit helps, however.\n\t\t\t<\/li>\n<li>\n\t\t\t\tIntel has a nice tool to analyse userspace misbehaviour. It&#8217;s called<br \/>\n\t\t<strong>ticktool<\/strong> and tells you which applications keep the CPU from<br \/>\n\t\tsleeping. Having identified those, stracing the process in question can give you<br \/>\n\t\ta better idea of what&#8217;s going on. Next step: Fixing it. Intel will release the<br \/>\n\t\ttool on their website intellinuxpower.org (not up yet) shortly, rumours are<br \/>\n\t\t&#8220;within a few days&#8221;.\n\t\t\t<\/li>\n<li>\n\t\t\t\t<strong>Synchronising timer events<\/strong> can also help a lot. 5<br \/>\n\t\ttimers spread over the second force the cpu to wake up much more often than 5<br \/>\n\t\ttimers running all at once. Result: the CPU sleeps longer, you save battery<br \/>\n\t\tlife. There seems to be a patch doing this flying around in Oslo, although there<br \/>\n\t\tare probably some things that need consideration before this can be widely<br \/>\n\t\tdeployed.\n\t\t\t<\/li>\n<li>\n\t\t\t\tIntel will be working on a <strong>profile manager<\/strong> that should<br \/>\n\t\tmake it easy for userspace to specify power-profiles for various scenarios.<br \/>\n\t\tSwitching of devices and putting devices into a lower powerstate when they&#8217;re<br \/>\n\t\tnot used. Especially USB is a big offender, although recent kernels (2.6.21,<br \/>\n\t\tespecially) have mechanics to suspend those battery-drainers when they&#8217;re not<br \/>\n\t\tuses). A proposal will pop up on relevant mailinglists within a couple of weeks.\n\t\t\t<\/li>\n<li>\n\t\t\t\t<strong>Powermanager<\/strong> (the battery applet used in Kubuntu) will<br \/>\n\t\tbe ported to Qt4 for Gutsy. There&#8217;s very little KDE specific stuff in there, so<br \/>\n\t\tit should be possible without losing lots of functionality. Kpowersave is deemed<br \/>\n\t\tto complicated from a user&#8217;s point of view. Still, it would be interesting to<br \/>\n\t\tknow if kpowersave is being ported to KDE4, or if one should think about that<br \/>\n\t\tfunctionality. powermanager is not distro-dependant, it does everything via HAL.<br \/>\n\t\tI don&#8217;t think a python application is a viable option to have in KDE4 default<br \/>\n\t\tand running since it adds about 8MB of extra memory in use and takes a bit long<br \/>\n\t\tto start, especially with cold caches.\n\t\t\t<\/li>\n<li>\n\t\t\t\t<strong>AMD\/ATI&#8217;s fglrx driver<\/strong> is a total pain in the ass. In<br \/>\n\t\tfact, it is the one component driver that is most complained about. ATI just<br \/>\n\t\tdoesn&#8217;t seem to care (&#8220;Increase your market share by a factor of 5 and we might<br \/>\n\t\tfix the drivers&#8221;). I can only encourage people to actively avoid buying hardware<br \/>\n\t\tcontaining ATI chips. Try to get an intel one. Given the bad quality of the<br \/>\n\t\tfglrx driver and the lack of features, you&#8217;re Free Desktop will be able to take<br \/>\n\t\tadvantage of much more eye-candy and powermanagement features.<br \/>\n\t\t\t\tATI&#8217;s fglrx module is needed on my notebook, there&#8217;s a x1300 chip in<br \/>\n\t\tthere, which is currently not supported by a free driver. Finding a<br \/>\n\t\tkernel-version \/ drvier-version combination that actually does suspend with this<br \/>\n\t\tblob loaded took me a week and probably two dozen recompiles of various kernel<br \/>\n\t\tversions. ATI&#8217;s engineers seem to actively ignore this issue. One of the latest<br \/>\n\t\treleases contained a new user interface tool which makes it possible to change<br \/>\n\t\tfor example anti-aliasing setting for the video card. It doesn&#8217;t support things like<br \/>\n\t\ttexture_to_pixmap (useful for compositing features), proper suspend support<br \/>\n\t\t(refuses to resume properly in >1 of 10 cases), you often have to wait for it to<br \/>\n\t\tsupport recent kernels (happened with 2.6.20, took roughly 2 months while a patch was<br \/>\n\t\tin the wild). AMD\/ATI engineers seem to completely ignore the user&#8217;s<br \/>\n\t\tneeds. So by all means: <strong>Avoid buying ATI chips if you want your Free Operating<br \/>\n\t\tsystem to run well.<\/strong>\n\t\t\t<\/li>\n<\/ul>\n<p>\t\tSo there&#8217;s a lot of exciting stuff going on in the powermanagement world.<br \/>\n\t\tBattery life and power consumption of your device will improve on the software<br \/>\n\t\tside.<\/p>\n<p \/>\n","protected":false},"excerpt":{"rendered":"<p>There&#8217;s quite some discussion about powermanagement here at the Ubuntu Developers Summit in sunny Sevilla. There are quite some Intel people around here, providing lots of insight in powermanagement on a hardware and driver level. Here&#8217;s a couple of points that have come up. First, the good news. KDE is in a pretty good shape&hellip; <a class=\"more-link\" href=\"https:\/\/vizZzion.org\/blog\/2007\/05\/powermanagement-improvements\/\">Continue reading <span class=\"screen-reader-text\">Powermanagement improvements.<\/span> <span class=\"meta-nav\" aria-hidden=\"true\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[29],"tags":[],"class_list":["post-1296","post","type-post","status-publish","format-standard","hentry","category-kde"],"_links":{"self":[{"href":"https:\/\/vizZzion.org\/blog\/wp-json\/wp\/v2\/posts\/1296","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vizZzion.org\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/vizZzion.org\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/vizZzion.org\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/vizZzion.org\/blog\/wp-json\/wp\/v2\/comments?post=1296"}],"version-history":[{"count":0,"href":"https:\/\/vizZzion.org\/blog\/wp-json\/wp\/v2\/posts\/1296\/revisions"}],"wp:attachment":[{"href":"https:\/\/vizZzion.org\/blog\/wp-json\/wp\/v2\/media?parent=1296"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vizZzion.org\/blog\/wp-json\/wp\/v2\/categories?post=1296"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vizZzion.org\/blog\/wp-json\/wp\/v2\/tags?post=1296"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}