Re: RFC: PCI SD host controller driver & mmc/mmcsd modules improvements
Alexander Motin <[email protected]>
| Newsgroups | gmane.os.freebsd.current,gmane.os.freebsd.devel.arm,gmane.os.freebsd.devel.mobile |
|---|---|
| Message-ID | <[email protected]> |
Stanislav Sedov wrote: > On Wed, 15 Oct 2008 23:25:11 +0300 > Alexander Motin <[email protected]> mentioned: >> Completely fortunate I have noticed that number of iterations depends on >> my laptop power source. After small investigation I have found that it >> actually depends on dev.cpu.0.freq value. With default value 2400 I have >> only several iterations. But every double frequency decrease doubles >> iteration count. With minimum value 100MHz I have more then 100 >> iterations. Same time it doesn't looks like this time is a real wall >> time. It looks like DELAY() used in a loop has some problems with time >> counting. > > What do you mean? DELAY(9) on your laptop doesn't correspond to the > real time? Yes. It works fine when laptop operates at full frequency, but proportionally reduces time interval when powerd drops frequency down. I have also evidence about the same problem on another laptop with 7.1-PRERELEASE. > AFAIK, DELAY(9) relies on current timecounter for time > accountiong, so there might be problems with it. Have you tried > switching the kern.timecounter.hardware sysctl to see if it will > affect results? It was late and I am not very aware in FreeBSD time counting, so I have not tried to investigate it deeper. -- Alexander Motin _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "[email protected]"