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New Kernel 2.4 Development Branch (-mjc)
Ivo writes: "kerneltrap is reporting: Michael Cohen announced to the lkml his intention to begin a new 2.4 development tree. The first release of his -mjc branch includes a number of performance enhancing patches, including Robert Love's preemptible kernel patch, Rick van Riel's reverse mapping patch and George Anzinger's real time scheduler patch. Michael says of this patch, "I feel that there's need for a rapidly developing '-ac [like]' tree, and so, here we go. Feel free to test it""
So how much gain in performance (or apparent performance) should one expect after applying this combined patch? Are the performance gains only applicable under special circumstances? Are they focused more on desktop apps than server?
I doubt you will see ANY performance enhancements with this patch - in fact, under most circumstances, performance will be worse.
The patch MOSTLY addresses a need to have shorter latency responses under linux. So the real benefit will be seen if you, say, run xmms, browse the web on a java intensive site, and do a make -j10 bzImage at the same time. On most machines this will cause xmms to stutter a little - either an audio skip or the text in the scrolling windows will stop and start. With the patch you can expect perfect xmms performance under broader circumstances.
This has the most significant implications for audio and video under linux - things that require short latencies to perform properly. This is questionably the most needed area of improvement for the linux kernel for desktop use.
However, if you time kernel compiles or run lmbench, you'll probably see slightly (but not hugely) worse results. You can expect that changes to address these issues will be incorporated in mainline kernels eventually, although not necessarily in the form that these patches take. Maybe - it will be interesting to see it sort out.