On Sun, Jul 24, 2016 at 01:06:40PM -0500, Bruce Dubbs wrote: > > Checking, CONFIG_HZ=1000 seems to be the default, at least on my systems. I > have never set it directly that I recall, but I generally start on a new > system with 'make defconfig' and that sets it for me. > > If someone starts with an old config file and runs 'make oldconfig', that > may account for propagating a poor setting for this parameter. > > From the kernel help: > > Allows the configuration of the timer frequency. It is customary to have > the timer interrupt run at 1000 Hz but 100 Hz may be more beneficial for > servers and NUMA systems that do not need to have a fast response for user > interaction and that may experience bus contention and cacheline bounces > as a result of timer interrupts. Note that the timer interrupt occurs on > each processor in an SMP environment leading to NR_CPUS * HZ number of > timer interrupts per second. > > -- Bruce > ISTR that over the years I have had various values there, including 1000 at one time (but I probably didn't try playing a DVD on vlc while I was running like that).
But I suspect I dropped back to 250 because my machines were underpowered and I had not noticed any benefit from 1000. What I normally do is build several kernels during the -rc stages. On my intels I have not yet hit any video problems (I've been lucky, a lot of people seem to still get problems on intel because there is such a wide range of hardware). But on AMD my A4 and my A10 had problems - in each case my reports led to them getting fixed before the release. So I consider that testing kernels is worthwhile ;-) And for a new kernel I look at the questions, and the help, in menuconfig and make a decision about what I think will be best - then I carry that forward unless it turns out to give obvious problems. So, even if I had started with defconfig (and that never used to match my cheap AMD machines!) I diverge from it over time. Interestingly, my i7 haswell has 8 cores (with hyperthreading), my i3 has 2/4, my phenom has 4 (arguably), so even at 250 there are a lot of interrupts. ĸen -- `I shall take my mountains', said Lu-Tze. `The climate will be good for them.' -- Small Gods -- http://lists.linuxfromscratch.org/listinfo/blfs-dev FAQ: http://www.linuxfromscratch.org/blfs/faq.html Unsubscribe: See the above information page
