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Reply-To: "Hillf Danton" <hillf.zj@alibaba-inc.com>
From: "Hillf Danton" <hillf.zj@alibaba-inc.com>
To: <mhocko@kernel.org>, <linux-mm@kvack.org>
Cc: "'Andrew Morton'" <akpm@linux-foundation.org>,
        "'Linus Torvalds'" <torvalds@linux-foundation.org>,
        "'Mel Gorman'" <mgorman@suse.de>,
        "'Johannes Weiner'" <hannes@cmpxchg.org>,
        "'Rik van Riel'" <riel@redhat.com>,
        "'David Rientjes'" <rientjes@google.com>,
        "'Tetsuo Handa'" <penguin-kernel@I-love.SAKURA.ne.jp>,
        "'LKML'" <linux-kernel@vger.kernel.org>,
        "'Michal Hocko'" <mhocko@suse.com>, "Christoph Lameter" <cl@linux.com>
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In-Reply-To: <1446131835-3263-3-git-send-email-mhocko@kernel.org>
Subject: Re: [RFC 2/3] mm: throttle on IO only when there are too many dirty and writeback pages
Date: Fri, 30 Oct 2015 12:18:50 +0800
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> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -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)
> +				congestion_wait(BLK_RW_ASYNC, HZ/10);
> +			else
> +				cond_resched();
> +

Looks the vmstat updater issue is not addressed.
>  			goto retry;
>  		}
>  	}
> --
> 2.6.1