On Tue, Nov 8, 2022 at 11:53 AM Mark Millard <mark...@yahoo.com> wrote:
> On Nov 7, 2022, at 19:28, Warner Losh <i...@bsdimp.com> wrote:
> >
> > . . .
> > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 256929, size: 4096
> > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 3628, size: 4096
> > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 255839, size: 40960
> > pid 46153 (c++), jid 0, uid 0, was killed: a thread waited too long to
> allocate a page
> > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 255857, size: 28672
> > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 3634, size: 8192
> > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 256037, size: 4096
> > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 255320, size: 8192
> >
> > This means that paging to the swap partition and/or swap file took too
> long (> 30 seconds... that's all that indefinite means).
>
> FYI: I think the "indefinite wait buffer" bound that leads
> to those messages is 20 sec (the hz*20 below):
>
> /*
> * Wait for the pages we want to complete. VPO_SWAPINPROG is
> always
> * cleared on completion. If an I/O error occurs, SWAPBLK_NONE
> * is set in the metadata for each page in the request.
> */
> VM_OBJECT_WLOCK(object);
> /* This could be implemented more efficiently with aflags */
> while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) {
> ma[0]->oflags |= VPO_SWAPSLEEP;
> VM_CNT_INC(v_intrans);
> if (VM_OBJECT_SLEEP(object, &object->handle, PSWP,
> "swread", hz * 20)) {
> printf(
> "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n",
> bp->b_bufobj, (intmax_t)bp->b_blkno,
> bp->b_bcount);
> }
> }
> VM_OBJECT_WUNLOCK(object);
>
> But the "was killed: a thread waited too long to allocate a page" is
> tied to a total of 30 sec (3*10sec) from:
>
> vm.pfault_oom_attempts= 3
> vm.pfault_oom_wait= 10
>
> (Presuming that you had defaults at the time.)
>
Confirming the default values.
root@generic:~ # sysctl -a | grep pfault_oom
vm.pfault_oom_wait: 10
vm.pfault_oom_attempts: 3
>
> > It also means that it can't write to backing store dirty pages to give
> to another process...
> >
> > Typical reason is that the disk / flash is not responsive to writes for
> some reason. You'll need to find why... I'd look at trims.
> >
> > Or.... if you can't change the disk... you need to put less memory
> pressure on it..
>
>
>
>
>
> ===
> Mark Millard
> marklmi at yahoo.com
>
>
