On Mon 11 Oct at 22:32:06 +0200 t...@linutronix.de said: > On Mon, 11 Oct 2010, Tim Pepper wrote: > > > I'm not necessarily wanting to open up the age old question of "what is > > a good HZ", but we were doing some testing on timer tick overheads for > > HPC applications and this came up... > > Yeah. This comes always up when the timer tick overhead on HPC is > tested. And this patch is again the fundamentally wrong answer.
Yep. Long term no hz is definitely the goal. I'm not sufficiently connected to the -rt space I guess to have followed that there's somebody again looking in that direction. The rfc patch was mostly just a minimal is there anything simple we can do in the meantime exercise. > We have told HPC folks for years that we need a kind of "NOHZ" mode > for HPC where we can transparently switch off the tick when only one > user space bound thread is active and switch back to normal once this > thing terminates or goes into the kernel via a syscall. I'd not heard of this in between NOHZ-y idea...sounds promising. We'd talked about different non-idle no hz approaches in the past year or so, some of which were on the veeery complicated side of the spectrum. > Sigh, nothing > happened ever except for repeating the same crap patches over and > over. I'll check out what Frederic is doing. Thanks for the pointer and apologies for the noise. -- Tim Pepper <lnxni...@linux.vnet.ibm.com> IBM Linux Technology Center _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
