Hello Jordan > > - on one hand, on an Asus laptop with a Core i3 : latency 2.3 msec > > with the 2.6.33.7.2-rt kernel and 23 msec with a 2.6.37 preempt kernel; > > 23msec with 2.6.37 preemptive kernel is terrible. For sure 23 msec is terrible; I was so surprised to see that! Not one of my > machines would perform that badly (and most use 2.6.37.3). Some are > also considerably older (like 5years older) than your asus laptop.. > > > - on the other hand, on a Lenovo Thinkpad Core i5 : latency 2.3 msec > > with the 2.6.33.7.2-rt kernel and 2.3 msec (yes the same) with a 2.6.37 > > preempt kernel !! > > that's not surprising, that is what i would expect to see. 2.6.33-rt > is getting quite dated, and old. For industrial / embedded > applications it might be the only option but for Linux audio / video > editing, there are preemptive kernels that work very well. > > > Of course the Lenovo Thinkpad is a very good laptop, but how come that there is such a big difference? > > someone can probably answer this better, but i think it comes down to > hardware / software design / implementation - some PCs work better > because of the quality of parts, the software and how well they > integrate. > > *** ....and how well-supported each component is under Linux. *** Yes Lenovo Thinkpad are famous for having good performance... and furthermore the T410s is "Ubuntu certified". However I experience hang on with the 2.6.33.7.2-rt kernel, but I have a touchscreen (input = 4 fingers multitouch working natively under Maverick... really great) and I suspect the mutitouch screen is responsible of this. Hopefully the performaces og the preempt are great! > > > So, I have observed the same quality of performance as Madovsky but not > > on every machine I've used... I don't have a clue why.... > > I also have observed the same thing. i actually only use RT on 1 > computer right now. On the Rest of my machines, 2.6.37.3-zen (PREEMPT, > BFS and BFQ v2.0 + optimizations) works wonders. > In every use i have 2.6.37 is better ( i am a pro-audio person ). > > I will say between 2.6.33 and 2.6.38 they have been many MANY changes, > so i am not surprised that 2.6.38 performs as well as 2.6.33-rt 9or > even just close). 2.6.38 (i believe) is the First kernel to have BKL > (Big kernel Lock) completely removed ....and also CFS (completely fair > scheduler) have changed quite a bit (since .33) and has been more > optimized. those 2 factors alone, should reduce latency. Coupled with > other fixes and changes in the kernel - should explain these kinds of > observations. > > just my 2 cents > > jordan Thank you for those explanations Victor -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
