From: Florin A. <fl...@an...> - 2002-11-19 18:36:49
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Quoting Miguel Freitas <mi...@ce...>: > redhat says the rmap vm they use is great and it seemed quite the > opposite to me: responsiveness looks much worse under rh kernel > than > stock kernels (2.4.17 or 2.4.19, for example). with rh kernel i > experienced long delays when resuming swapped out apps and even > hiccups > with xmms that where gone from my system a long ago... My experience is quite the opposite. On servers, there is little doubt in my mind that the latest RH kernels are a huge improvement. Running applications with lots of threads/processes (MySQL, Apache) is much better on the new kernels; looks like the context switches are performed a lot faster. Even select() applications (Squid) seem to behave better. However, we're not talking here about typical server workloads. RMAP is not the only change. They also elevated the interrupt clock frequency 5 times. As a direct result of that, now i can transcode from VOB to DivX and my system continues to feel snappy and fast. Under the older kernels, using transcode (or any other multi-thread/process CPU hog) made my desktop difficult to use (sluggish mouse, lazy apps, etc), despite the fact that the CPU is fairly powerful (AthlonXP 1800+). I'm using Xine and XMMS to play all kind of media content, including DVDs, on the new RH kernels, and didn't had any problem whatsoever. If anything, the performance seems to be better when the system is under heavy load. One thing you may have forgotten is the interrupt table. I forgot that too. Basically, if you have overlapping interrupts (different devices sharing the same interrupt), you'll notice performance penalties, or even hiccups with multimedia applications under certain circumstances. Make sure your interrupts are spread out evenly. This is a good advice for using any media player, not just Xine. By the way, anyone has any hints on spreading out the interrupts on an MCI nForce motherboard? ;-) (using the embedded GeForce) > to make things even worse hdparm couldn't enable dma on my dvdrom > with > rh kernel! Dude, c'mon, it's in the release notes... Add this to your /etc/modules.conf: options ide-cd dma=1 It's disabled by default because too many people complained about problems with DMA on buggy CD-ROMs. Overall, i was extremely impressed by the new kernels. I do regularly a lot of "heavy-duty" :-) multimedia stuff, and with these kernels the CPU hogs do not eat my entire CPU anymore; well, they still do it, but somehow the other applications feel more responsive. My feeling is that they focused mainly on the server side of things, but anyway i saw a lot of improvement on my multimedia desktop too. -- Florin Andrei http://florin.myip.org/ ------------------------------------------------- This mail sent through IMP: http://horde.org/imp/ |