Messages in this thread | | | Date | Mon, 20 Jul 2009 17:44:50 +0530 | From | Balbir Singh <> | Subject | Re: [PATCH 10/10] ksm: change ksm nice level to be 5 |
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* Izik Eidus <ieidus@redhat.com> [2009-07-20 14:48:04]:
> Balbir Singh wrote: >> * Izik Eidus <ieidus@redhat.com> [2009-07-17 20:30:50]: >> >> >>> From: Izik Eidus <ieidus@redhat.com> >>> >>> ksm should try not to disturb other tasks as much as possible. >>> >>> Signed-off-by: Izik Eidus <ieidus@redhat.com> >>> --- >>> mm/ksm.c | 2 +- >>> 1 files changed, 1 insertions(+), 1 deletions(-) >>> >>> diff --git a/mm/ksm.c b/mm/ksm.c >>> index 75d7802..4afe345 100644 >>> --- a/mm/ksm.c >>> +++ b/mm/ksm.c >>> @@ -1270,7 +1270,7 @@ static void ksm_do_scan(unsigned int scan_npages) >>> >>> static int ksm_scan_thread(void *nothing) >>> { >>> - set_user_nice(current, 0); >>> + set_user_nice(current, 5); >>> >> >> Is the 5 arbitrary? Why not +19? What is the intention of this change >> - to run when no other task is ready to run? >> > > Hey Balbir, > > I thought about giving it the lowest priority of nice before I did this > patch, but then I came into understanding that it isn't right, > Although ksm should not distrub other tasks while they are running, it > does need to run while they are running, > most of the use cases for ksm is to find identical pages in real time > while they are changing in the application, so giving it the lowest > priority doesn't seems right to me, > > But my understanding of how the nice prioritys are working is just my > intuition, so if you know better and think that for the use case i > described above other nice priority is better fit, tell me and I wont > have any problem to change. > >
I was just checking to see why 5? May be it might be a good idea to document or at-least have rules on what priorities kernel threads can take?
>> >>> while (!kthread_should_stop()) { >>> if (ksm_run & KSM_RUN_MERGE) { >>> >> >> >
-- Balbir
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