![]() | |||||||||||||
Messages in this thread |
* Horst von Brand <vonbrand@inf.utfsm.cl> [2004-03-14]: > Micha Feigin <michf@post.tau.ac.il> said: > > Is it possible to find out what the kernel's notion of HZ is from user > > space? > > What for? It should be invisible to userspace... > A related issue that's bugged me for a long time is lack of userspace access to the quantity that's called 'freq_scale' in 2.4, where it's (1<<SHIFT_HZ)/HZ for HZ!=100 and 128/128.125 for HZ==100. (I haven't started to reverse-engineer the equivalent value in 2.6, I took a quick look once and concluded things had got a little more hairy.) My interest is that I maintain (in spare-time) an NTP application called chrony (http://chrony.sunsite.dk/), originally written to be good for dial-up, i.e. NTP servers accessible for a short window once or twice a day. This app wants to tune the parameters it passes to adjtimex() to take a best shot at keeping the system clock correct over the potentially 'long' offline period. To do this well, it has to reverse-compensate for the freq_scale multiplier that the kernel will apply to the frequency value passed to adjtimex(). Getting the right value for this across different kernels has always been a fragile exercise. -- Richard \\\ SH-4/SH-5 Core & Debug Architect Curnow \\\ SuperH (UK) Ltd, Bristol - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
| Last update: 2005-03-22 13:01 [from the cache] ©2003-2008 | |||||||||||||