Huh... the original version could result in occasional ata drive lockups. Hopefully improved version can be found on the same URL: http://www.tel.fer.hr/zec/BSD/pm/4.8-ich-ds.patch Marko On Friday 17 October 2003 02:20, Marko Zec wrote:> From http://www.tel.fer.hr/zec/BSD/pm/4.8-ich-ds.patch you can fetch an > experimental patch for the 4.8-RELEASE kernel that allows for significant > power savings on mobile systems by utilizing a feature called "deeper sleep > mode". The deeper sleep mode is available on recent Intel mobile processors > (Pentium III-M, Pentium IV-M and "Centrino" Mobile Pentium) in combination > with ICH3 / ICH4 chipsets, and is used to simultaneously stop the CPU clock > and significantly lower the chip core voltage. When in such a state, the > CPU is supposed to consume only around 0.6 W, according to Intel specs. > > The power saving policy in idle loop is controlled by the > machdep.cpu_idle_hlt sysctl, which now has two new modes: > > Mode 0 (std) Do not halt the CPU, return from the idle loop as soon as > possible. > > Mode 1 (std) Halt the CPU using the "hlt" instruction. CPU clock is not > stopped (TSC keeps counting). > > Mode 2 (new) Halt the CPU using APM BIOS call followed by a "hlt". This > method stops the clock, thus saving slightly more power. > > Mode 3 (new) Halt the CPU by entering the deeper sleep mode (max. power > savings). > > The battery life extension that can be obtained on an idle system using > this patch looks very promissing. Here's what I could observe on my > ThinkPad X30 (Pentium III-M 1200, ICH-3 chipset) with a slightly worn-out > battery: > > +---------+----------------------+----------------------+ > > |cpu_idle | LCD ON (dim) | LCD OFF | > | mode | Bat. life | gain | Bat. life | gain | > > +---------+-----------+----------+-----------+----------+ > > | 1 | 4:03 | | 5:12 | | > > +---------+-----------+----------+-----------+----------+ > > | 2 | 4:10 | 2% | 5:23 | 3% | > > +---------+-----------+----------+-----------+----------+ > > | 3 | 4:48 | 18% | 6:21 | 22% | > > +---------+-----------+----------+-----------+----------+ > > I had no ICH-4 based laptop available for testing, so I cannot promise that > the patch will work on such systems, although it should. > > The patch also introduces a new sysctl machdep.speedstep, which can be used > to directly controll the CPU clock frequency / operating voltage. If your > BIOS already correctly does this job you probably won't need this sysctl, > however the BIOS in my ThinkPad annoyingly persists with the same speedstep > mode regardless of the power source (external/battery), so I had to > implement a method to control it. > > Anyhow, hope you like the patch... The usual liability disclaimer applies - > if anything goes wrong with your machinery or data, you are on your own :-) > Have fun, > > Marko