On Thu, Apr 15, 2010 at 11:31:52AM +0800, KOSAKI Motohiro wrote: > > > Many applications (this one and below) are stuck in > > > wait_on_page_writeback(). I guess this is why "heavy write to > > > irrelevant partition stalls the whole system". They are stuck on page > > > allocation. Your 512MB system memory is a bit tight, so reclaim > > > pressure is a bit high, which triggers the wait-on-writeback logic. > > > > I wonder if this hacking patch may help. > > > > When creating 300MB dirty file with dd, it is creating continuous > > region of hard-to-reclaim pages in the LRU list. priority can easily > > go low when irrelevant applications' direct reclaim run into these > > regions.. > > Sorry I'm confused not. can you please tell us more detail explanation? > Why did lumpy reclaim cause OOM? lumpy reclaim might cause > direct reclaim slow down. but IIUC it's not cause OOM because OOM is > only occur when priority-0 reclaim failure. No I'm not talking OOM. Nor lumpy reclaim. I mean the direct reclaim can get stuck for long time, when we do wait_on_page_writeback() on lumpy_reclaim=1. > IO get stcking also prevent priority reach to 0. Sure. But we can wait for IO a bit later -- after scanning 1/64 LRU (the below patch) instead of the current 1/1024. In Andreas' case, 512MB/1024 = 512KB, this is way too low comparing to the 22MB writeback pages. There can easily be a continuous range of 512KB dirty/writeback pages in the LRU, which will trigger the wait logic. Thanks, Fengguang > > > > > > Thanks, > > Fengguang > > --- > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index e0e5f15..f7179cf 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -1149,7 +1149,7 @@ static unsigned long shrink_inactive_list(unsigned long max_scan, > > */ > > if (sc->order > PAGE_ALLOC_COSTLY_ORDER) > > lumpy_reclaim = 1; > > - else if (sc->order && priority < DEF_PRIORITY - 2) > > + else if (sc->order && priority < DEF_PRIORITY / 2) > > lumpy_reclaim = 1; > > > > pagevec_init(&pvec, 1); > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Please read the FAQ at http://www.tux.org/lkml/ > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>