On Monday 02 March 2009, Denys Fedoryschenko wrote: > On Monday 02 March 2009 19:23:09 Sitsofe Wheeler wrote: > > On Mon, Mar 02, 2009 at 06:33:46PM +0200, Denys Fedoryschenko wrote: > > > CPUFreq infrastructure much more powerful. > > > -d --min <FREQ> > > > new minimum CPU frequency the governor may select. > > > -u --max <FREQ> > > > new maximum CPU frequency the governor may select. > > > -g --governor <GOV> > > > new cpufreq governor. > > > > > > This things you cannot do over inserting values over ACPI. Sure you can > > > reinvent the wheel, but why? > > > > I guess I don't understand why you would want scaling if it didn't save > > you any power... > If i will limit current in certain limits, rather than using high current, i > will have in result higher efficiency of discharging battery. > The discharge curves for a Lithium Ion cell below show that the effective > capacity of the cell is reduced if the cell is discharged at very high rates > (or conversely increased with low discharge rates). This is called the > capacity offset and the effect is common to most cell chemistries. > If the discharge takes place over a long period of several hours as with some > high rate applications such as electric vehicles, the effective capacity of > the battery can be as much as double the specified capacity at the C rate. > This can be most important when dimensioning an expensive battery for high > power use. The capacity of low power, consumer electronics batteries is > normally specified for discharge at the C rate whereas the SAE uses the > discharge over a period of 20 hours (0.05C) as the standard condition for > measuring the Amphour capacity of automotive batteries. The graph below shows > that the effective capacity of a deep discharge lead acid battery is almost > doubled as the discharge rate is reduced from 1.0C to 0.05C. For discharge > times less than one hour (High C rates) the effective capacity falls off > dramatically. > This means even i need to recode on battery movie (clearly need same amount of > processing power), if i do it with 100% CPU available let's say in 30 > minutes, and if i do it with 50% CPU available in 60 minutes, at the end i > should have DIFFERENT amount of remaining battery. > > Another example, if i run screensaver i want governor powersave(so some crazy > flash plugin don't dry out battery till i come back) , if i run on battery i > will put conservative and limit frequency range to max 50% of CPU power, so i > can be sure my laptop lasts enough time. This in case battery time matter for > me more than computing power. Sure i will prefer some universal way, so i can > set same rules on Core 2 Duo based laptop, and cheap Celeron. Cpufreq provide > me useful framework for this job, and important SAME API everywhere. Less > efficient on p4-clockmod, and very efficient on true "mobile" processors. > > * Many things quoted from http://www.mpoweruk.com/performance.htm You should have added linux-acpi to the CC list and since the change in question was very much on purpose, I'm not going to list (at least for now). Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
