On Wed, Jun 21, 2023 at 04:40:59PM -0500, Scott Cheloha wrote: > On Wed, Jun 21, 2023 at 01:03:03PM -0600, Chris Waddey wrote: > > Sorry for breaking the thread, I wasn't subscribed to misc, but found > > this in the archives. > > > > After some testing, it looks like the recent uvm_meter() commit is what > > did this (to my machine at least). > > > > The git commit for that is 71d823ace2523fb9fee2d1ab9b4d92a18d3f5714. > > > > I compiled the commit right before it in the logs and booted no problems > > with a GENERIC.MP kernel config, but that one broke it. > > > > I'm not as familiar with CVS, so apologies for not having the commit > > from there. > > > > Here is the commit message if that helps, though I those on tech will > > know it regardless: > > > > schedcpu, uvm_meter(9): make uvm_meter() an independent timeout > > > > uvm_meter(9) should not base its periodic uvm_loadav() call on the UTC > > clock. It also no longer needs to periodically wake up proc0 because > > proc0 doesn't do any work. schedcpu() itself may change or go away, > > but as kettenis@ notes we probably can't completely remove the concept > > of a "load average" from OpenBSD, given its long Unix heritage. > > > > So, (1) remove the uvm_meter() call from schedcpu(), (2) make > > uvm_meter() an independent timeout started alongside schedcpu() during > > scheduler_start(), and (3) delete the vestigial periodic proc0 wakeup. > > > > With input from deraadt@, kettenis@, and claudio@. deraadt@ cautions > > that this change may confuse administrators who hold the load average > > in high regard. > > > > Thread: https://marc.info/?l=openbsd-tech&m=168710929409153&w=2 > > > > general agreement with this direction from kettenis@ > > ok claudio@ > > > > If I should repost on tech, let me know. > > Thank you for bisecting the issue. > > Could you try this tweaked version of that patch? I am trying to > narrow down the chunk responsible for the hang. I cannot trigger the > hang on any of my machines. Clearly you have something in your setup > that I don't. > > There aren't many possibilities. > > 1. Separating uvm_meter() from schedcpu(). > 2. Not using the UTC clock to decide when to update load averages. > 3. Not periodically awakening proc0. > > Let's try 3. > > Index: kern/sched_bsd.c > =================================================================== > RCS file: /cvs/src/sys/kern/sched_bsd.c,v > retrieving revision 1.76 > diff -u -p -r1.76 sched_bsd.c > --- kern/sched_bsd.c 21 Jun 2023 21:16:21 -0000 1.76 > +++ kern/sched_bsd.c 21 Jun 2023 21:40:17 -0000 > @@ -234,7 +234,6 @@ schedcpu(void *arg) > } > SCHED_UNLOCK(s); > } > - uvm_meter(); > wakeup(&lbolt); > timeout_add_sec(to, 1); > } > @@ -669,6 +668,7 @@ scheduler_start(void) > > rrticks_init = hz / 10; > schedcpu(&schedcpu_to); > + uvm_meter(NULL); > > #ifndef SMALL_KERNEL > if (perfpolicy == PERFPOL_AUTO) > Index: uvm/uvm_meter.c > =================================================================== > RCS file: /cvs/src/sys/uvm/uvm_meter.c,v > retrieving revision 1.44 > diff -u -p -r1.44 uvm_meter.c > --- uvm/uvm_meter.c 21 Jun 2023 21:16:21 -0000 1.44 > +++ uvm/uvm_meter.c 21 Jun 2023 21:40:17 -0000 > @@ -65,6 +65,9 @@ > int maxslp = MAXSLP; /* patchable ... */ > struct loadavg averunnable; > > +#define UVM_METER_INTVL 5 > +struct timeout uvm_meter_to = TIMEOUT_INITIALIZER(uvm_meter, NULL); > + > /* > * constants for averages over 1, 5, and 15 minutes when sampling at > * 5 second intervals. > @@ -85,10 +88,10 @@ void uvmexp_read(struct uvmexp *); > * uvm_meter: calculate load average and wake up the swapper (if needed) > */ > void > -uvm_meter(void) > +uvm_meter(void *unused) > { > - if ((gettime() % 5) == 0) > - uvm_loadav(&averunnable); > + timeout_add_sec(&uvm_meter_to, UVM_METER_INTVL); > + uvm_loadav(&averunnable); > if (proc0.p_slptime > (maxslp / 2)) > wakeup(&proc0); > } > Index: uvm/uvm_extern.h > =================================================================== > RCS file: /cvs/src/sys/uvm/uvm_extern.h,v > retrieving revision 1.170 > diff -u -p -r1.170 uvm_extern.h > --- uvm/uvm_extern.h 21 Jun 2023 21:16:21 -0000 1.170 > +++ uvm/uvm_extern.h 21 Jun 2023 21:40:17 -0000 > @@ -414,7 +414,7 @@ void uvmspace_free(struct vmspace *); > struct vmspace *uvmspace_share(struct process *); > int uvm_share(vm_map_t, vaddr_t, vm_prot_t, > vm_map_t, vaddr_t, vsize_t); > -void uvm_meter(void); > +void uvm_meter(void *); > int uvm_sysctl(int *, u_int, void *, size_t *, > void *, size_t, struct proc *); > struct vm_page *uvm_pagealloc(struct uvm_object *,
That worked. Applied it to the last commit that worked for me, built GENERIC.MP, rebooted and everything seems normal.
