Hi jeff. Do you think? This has a very effort on OOo's compile problem. On Fri, 13 Feb 2004 06:31:39 +0900 Taku YAMAMOTO <taku_at_cent.saitama-u.ac.jp> wrote: > I observed that SCHED_ULE doesn't give fair amount of CPU time to processes > which are using scheduler-activation-based threads when other > (semi-)CPU-intensive, non-P_SA processes are running. > # for example, browsing a complicated web page while compiling some > # amount of code with nice 0. > After spending several hours, I finally tracked it down to the following > code in sched_ule.c: > <code> > **** snip **** > void > sched_switch(struct thread *td) > { > **** snip **** > if (TD_IS_RUNNING(td)) { > if (td->td_proc->p_flag & P_SA) { > kseq_load_rem(KSEQ_CPU(ke->ke_cpu), ke); > setrunqueue(td); > } else > kseq_runq_add(KSEQ_SELF(), ke); > **** snip **** > void > sched_add(struct thread *td) > { > **** snip **** > case PRI_TIMESHARE: > if (SCHED_CURR(kg, ke)) > ke->ke_runq = kseq->ksq_curr; > else > ke->ke_runq = kseq->ksq_next; > break; > **** snip **** > </code> > The problem is that setrunqueue() calls sched_add(), which resets ke_runq, > thus non-interactive threads are likely to be put into ksq_next regardless > of however much slices remaining. > On the contrary, threads of !P_SA processes stay in ksq_curr unless slices > have been expired, since !P_SA case bypass setrunqueue() => sched_add() > path. > In order to reduce the difference, I tested three different strategies. > 1. preserve ke_runq in P_SA case (ule_runq_preserve.patch) > This became a bit hackish, but I felt the characteristics of ULE were > well preserved. I confirmed and tested /usr/ports/japanese/openoffice-1.1 in this way. OOo's regcomp (on build) don't overrun. This is a good news for OOo users. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 11014 nork -8 0 22420K 8464K biowr 0:01 6.25% 6.25% regcomp - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - > 2. set ke_runq to ksq_next if the given thread is considered > non-interactive in !P_SA case (ule_runq_reset.patch) > I felt that the scheduler behaves a bit like the SCHED_4BSD does, which > I think is not good. > 3. use setrunqueue() (= sched_add()) in !P_SA case, too, like SCHED_4BSD > does (ule_sameas_sa.patch) > I felt that the scheduler behaves much more like the SCHED_4BSD (read: > good characteristics of ULE seemed to fade out), but it might be > scientifically correct. > In either way, P_SA processes were given reasonable amount of CPU time > relative to the !P_SA processes, while with unmodified scheduler, most of > CPU time was eaten up by cc1plus(PRI=136..139) and nearly zero CPU to > epiphany-bin(PRI=92 or so). > # checked with top, epiphany+libpthread and compiling 4k-lines C++ program > # with CXXFLAGS='-pipe -O3 etc...', took several minutes on Pen2_at_300MHz > Since I am totally unfamilier with the scheduler things, all of the three > can be completely wrong or irrelevant to the problem. But I hope one of > them brings some lights to scheduler gulus. > Thank you for reading, > taku > -- > -|-__ YAMAMOTO, Taku <taku_at_cent.saitama-u.ac.jp> > | __ < > Post Scriptum: Sorry for no concrete statistics :)Received on Fri Feb 13 2004 - 13:00:22 UTC
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