On 21/01/2008, Christian Boon <chris.boon@xxxxxxxxx> wrote: > Jesper Juhl schreef: > > On 21/01/2008, Christian Boon <chris.boon@xxxxxxxxx> wrote: > > > >> Hello, > >> > >> For my ARM processor (PXA255) i use kernel 2.6.22 and a kernel HZ value > >> of 1000. > >> > > [snip] > > > >> Am i doing something wrong here? Is this value converted to some sort of > >> userspace HZ? > >> I have tried it on x86 also and it gives the same behaviour. > >> > >> > > > > In old kernels the HZ value (in both kernel- and user-space) was 100 > > without the ability to change this. > > When the kernel added the option of other HZ values this was > > implemented as kernel-space only and the HZ value exposed to > > user-space was fixed at 100. This was done to avoid breaking > > applications that assumed a fixed HZ of 100. > > So, while the kernel may tick at 100, 250, 1000 or some other HZ > > values (or even be tick less), user-space will always see HZ as being > > 100. > > > > > Ok thanks, > is there another way to receive the tick counter in userspace? > I don't know of one, but that doesn't mean there isn't any :) But, why does your application care? If it needs to sleep for some amount of time it should just do so with sleep(), usleep(), select() or similar - it shouldn't need to know what the kernel Hz is... If it needs to know the amount of wall-clock time that has passed, then calling gettimeofday(), at intervals, is usually good enough. I'm currious as to why you need this...? -- Jesper Juhl <jesper.juhl@xxxxxxxxx> Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html Plain text mails only, please http://www.expita.com/nomime.html -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
