http://defect.opensolaris.org/bz/show_bug.cgi?id=6232
--- Comment #5 from Saurabh Mishra <saurabh.mishra at sun.com> 2009-02-17 10:56:38 --- Thanks. /Saurabh (In reply to comment #4) > (In reply to comment #0) > > Hi -- > > > > My comments are below :- > > > > - When PAD is enabled (event mode), where and how do we adjust P-states > > depending upon the CPU consumption/utilization? This should help laptops > > operating on battery. OR is it still done by cpu module in poll mode? > > In event based mode...the CPU module doesn't poll. P-state changes are driven > by changes in CPU utilization of the P-state domain that the dispatcher tracks > as part of it's broader CMT scheduling efforts. > > > usr/src/uts/common/disp/disp.c > > - I think extra overhead of 'for loop' (depending upon the group > > size) in pg_ev_thread_remain()/pg_ev_thread_swtch() can cause > > performance degradation in context switch path. It is also not so > > obvious as to why we need these callbacks during swtch(). > > The iteration performed there is actually not new. In the current gate, > PG_NRUN_UPDATE() invokes a function, pg_cmt_load() that walks the CPU's > processor groups, adjusting the load in each of them when the CPU transitions > between busy <=> idle. These callbacks replace those. > > PAD changes this in the sense that rather than walking the CPU's group of CMT > PGs, and adjusting the load in each of them, it instead walks the PGs and > invokes a function pointer, which (depending on the PG), may just adjust the > load in that PG, or (in the case of power domains) may call into the CPU power > manager. > > In the case where the thread is remaining on the CPU, there is an extra loop > traversal that wasn't there previously, so that the power manager can be > notified when a thread has reached the end of it's time quantum. It might be > possible to make this more efficient since only the power related PGs do > anything with this one...although that will definitely change down the road. -- Configure bugmail: http://defect.opensolaris.org/bz/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.
