---------- Forwarded message ---------- From: Chetan Nanda <chetannanda@xxxxxxxxx> Date: Wed, Jul 29, 2009 at 8:31 PM Subject: Re: picking next running process in CFS scheduler To: Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx> Cc: Kernelnewbies <kernelnewbies@xxxxxxxxxxxx> On Wed, Jul 29, 2009 at 6:31 PM, Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx> wrote: > > Hi Cheetan... > > Thanks for your fast reply... > > On Wed, Jul 29, 2009 at 6:15 PM, Chetan Nanda<chetannanda@xxxxxxxxx> wrote: > > > > > > On Wed, Jul 29, 2009 at 4:15 PM, Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx> > > wrote: > >> > >> Hi all > >> > >> I've tried to check related scheduler code and I've got impression > >> that in CFS scheduler, dynamic priority level no longer determines > >> which process will be picked up by the scheduler. Instead, it is now > >> the waiting time that becomes the primary factor to watch...the longer > >> it waits, thus it is treated "more unfair"...then it will be picked > >> ASAP. Is this correct? > > > > > > AFAIK, this is correct > > > >> > >> If it is correct, then is it still useful to assign different nice > >> level to mark the importance of a process? > > > > > > Waiting time for different process are virtual time, I mean waiting time > > depends on priority of the process also. > > Waiting time of a process with higher priority will increase faster so that > > it get picked sooner. > > Is it what I read as so called virtual clock? Yes, > So, may I say that nice > level (thus also dynamic priority, since I check that in CFS, static > prio=dynamic prio..CMIIW) is somekind of weight factor of waiting > time? For regular processes static priority is equal to dynamic priority. Yes waiting time depend on nice value of a process. May refer Chapter 2nd of "Professional Linux® Kernel Architecture" it have a fair amount of implementation detail on CFS. > > > -- > regards, > > Mulyadi Santosa > Freelance Linux trainer > blog: the-hydra.blogspot.com Thanks, Chetan Nanda -- regards, Mulyadi Santosa Freelance Linux trainer blog: the-hydra.blogspot.com -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
