<snip> >> Note: When running with the lowest multiplier, HDD I/O performance may >> suffer. In my case the lowest CPU rate is at 1000MHz and with full I/O >> load accross 1 or 2 HDDs the CPU load is below the treshold of the apm -C, >> so it doesn't speed up. If I switch it manually with apm -H the transfer >> rate doubles. No RAID here so we're speaking about 30MB/s with apm -C vs. >> 60MB/s for apm -H. Forgot to mention but this is for stuff served over >> samba meaning there is some network I/O involved also. >> > >Hi, >Re your answer, from man page APM(8) : > > -C Set apmd(8) to cool running performance adjustment mode. In >this > mode, when CPU idle time falls below 10%, apm raises hw.setperf > as much as necessary. Otherwise when CPU idle time is above >30%, > apm lowers hw.setperf as much as possible to reduce heat, noise, > and power consumption. > > -H Set apmd(8) to manual performance adjustment mode and hw.setperf > to 100. > >I don't understant why you have lower performances after "apm -C" while in my >opinion it should just adjust low / fast in function of the system load >requirement ? Are disk IO not consideredas CPU load ?
The disk I/O + samba doesn't stress the CPU enough so it does not speed up. Which is good :) I expect my disk I/O to keep CPU usage low, that's why we have all that DMA, I/O controllers and stuff. Bad thing is, with the lowest CPU multiplier, something else is slowed down. Maybe the communication with the southbridge or the CPU gets very ineffective in processing data from the bus or something completly different ... At the moment apm -C is not tunable and in my case with my hardware it is not sensitive enough but I don't care that much since I'm more concerned with power consumption than raw performance. Will it be a problem for you? I have no idea, you should try it with your hardware. Regards, Daniel.
