Thanks for the info. I haven't had the same problems, but I'd like my ATV running full-bore as well, so I took your advice.
Here's the corresponding line for mythbuntu: echo performance > /sys/devices/system/cpu/*/cpufreq/scaling_governor On Jul 31, 9:43 pm, brteag00 <[email protected]> wrote: > I've been bothered by this for months, and finally nailed it, so I > thought I'd share. The (wired) ethernet connection was intolerably > slow (100 Mbit connection with ~100-200 kbps throughput), but only in > some circumstances. In particular, it made installing my distro > unbearable - I had a huge pipe and it took something like 6 hours to > download a minimal Fedora 10 distro. > > I finally put together a solid test case and discovered that the > throughput actually goes UP when the processor is loaded - at 100% > load, the throughput is exactly what I'd expect from a 100 Mb link. > > It turns out that the buffer in the Realtek ethernet chip is really > small. With no load (say, filling up a video buffer), the processor > would go to sleep (ACPI state C3), and it would take so long to wake > back up that the buffer would fill up and packets would the lost. > When the lost packets didn't get ACKed, the sending TCP stack would > scale back the transmission rate. However, if the CPU was loaded > (say, playing back that video), then it would be awake enough to > handle the interrupt in a timely fashion and the throughput was fine. > > The fix is to keep the processor from going all the way into C3 sleep; > rather, we want the kernel's idle loop just to spin on an HLT > instruction so that it wakes back up faster. This is accomplished by > adding "idle=halt" to the kernel boot line, either in boot_linux.sh > (if you're using atv-boot=manual in com.apple.Boot.plist), or else in > your grub.conf file (if you're using a real bootloader.) > > A related issue can be caused by the CPU's clock frequency being > scaled back by the cpufreq governor - it's "ondemand" in most current > distros. Changing it to "performance" ( cat performance > /sys/ > devices/system/cpu/cpu0/cpufreq) on system startup alleviates this > problem, too. > > Thanks to sdavilla for an awesome project - now that this problem's > been nailed, my ATV is a kick-ass MythTV frontend. > > Brian --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/atv-bootloader?hl=en -~----------~----~----~----~------~----~------~--~---
