On Fri, Mar 26, 2010 at 3:47 PM, Daniel Quinn <expendabl...@danielquinn.org> wrote: > I don't know if this is a hardware issue or not, but I thought that maybe I'd > configured my kernel incorrectly and that this might be a known issue someone > here has run across in the past so here goes: > > My computer is a pretty impressive AMD 64 X2 Dual Core Processor 6400+ box > with 2GB of RAM and for the most part, I just use it to write code at work. > However, whenever I'm doing something CPU-intensive, two things happen: > > * The load on the box goes up to 4 > * The box intermittently wobbles from running at full-speed and dropping to > a crawl. This is best seen while watching Flash videos online, > compressing/encoding video, or compiling. Everything is fine for a few > minutes, then suddenly the rate of compiling/compression/playback etc. > drops to a crawl for about 1-3minutes, then back up to full speed. > > I don't know why it's happening. I've tried various kernel options with no > change in behaviour. Outside of that though, I don't know what to try. > Suggestions welcome :-(
My initial thoughts, it sounds like what I experienced a few kernels ago when they introduced the new group scheduler features. In my case I disabled "Group CPU scheduler" in kernel config and changed from SLUB back to SLAB. Also perhaps try to change your preemption model, timer frequency, NO_HZ mode. These things have all had noticeable differences to me in responsiveness over the years. If it's not a kernel issue, perhaps use "nice" to tame CPU-hungry processes, or "ionice" if they are disk-intensive. Be sure your Video Card is not overheating or going into low-power mode. Nvidia cards go into a super-slow-mode when they overheat (happened to me 3 times when the fan on the card died). When that happened, for example my FPS in glxgears would go from thousands down to double digits... I could see lines painting on the screen, it was painfully slow. Also, if your CPU has frequency scaling make sure it's not gone crazy, cat /proc/cpuinfo to see CPU speed, or powertop might be a more friendly way to view the P-States. Download memtest86+ from memtest.org and run it to be sure you don't have any faulty RAM (in my experience tests 5 and 8 are the only ones that ever show any errors, so you can save time by only running one full pass of all tests and then a multiple passes of 5 and 8 just to be sure it's good)
