Messages in this thread | | | Date | Fri, 30 Oct 2015 09:38:05 +0100 | From | Michal Hocko <> | Subject | Re: [RFC 2/3] mm: throttle on IO only when there are too many dirty and writeback pages |
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On Fri 30-10-15 14:48:40, KAMEZAWA Hiroyuki wrote: [...] > > @@ -3191,8 +3191,23 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > > */ > > if (__zone_watermark_ok(zone, order, min_wmark_pages(zone), > > ac->high_zoneidx, alloc_flags, target)) { > > - /* Wait for some write requests to complete then retry */ > > - wait_iff_congested(zone, BLK_RW_ASYNC, HZ/50); > > + unsigned long writeback = zone_page_state(zone, NR_WRITEBACK), > > + dirty = zone_page_state(zone, NR_FILE_DIRTY); > > + > > + if (did_some_progress) > > + goto retry; > > + > > + /* > > + * If we didn't make any progress and have a lot of > > + * dirty + writeback pages then we should wait for > > + * an IO to complete to slow down the reclaim and > > + * prevent from pre mature OOM > > + */ > > + if (2*(writeback + dirty) > reclaimable) > > Doesn't this add unnecessary latency if other zones have enough clean memory ?
We know we haven't made any progress the last reclaim round so any zone with a clean memory is rather unlikely.
-- Michal Hocko SUSE Labs
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