From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <385931845.25314@ustc.edu.cn> Date: Wed, 1 Aug 2007 09:19:25 +0800 From: Fengguang Wu Subject: Re: make swappiness safer to use Message-ID: <20070801011925.GB20109@mail.ustc.edu.cn> References: <20070731215228.GU6910@v2.random> <20070731151244.3395038e.akpm@linux-foundation.org> <20070731224052.GW6910@v2.random> <20070731155109.228b4f19.akpm@linux-foundation.org> <20070731230251.GX6910@v2.random> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070731230251.GX6910@v2.random> Sender: owner-linux-mm@kvack.org Return-Path: To: Andrea Arcangeli Cc: Andrew Morton , linux-mm@kvack.org, Nick Piggin List-ID: On Wed, Aug 01, 2007 at 01:02:51AM +0200, Andrea Arcangeli wrote: > diff --git a/mm/vmscan.c b/mm/vmscan.c [...] > @@ -912,6 +913,44 @@ static void shrink_active_list(unsigned > * altogether. > */ > swap_tendency = mapped_ratio / 2 + distress + sc->swappiness; > + > + /* > + * If there's huge imbalance between active and inactive > + * (think active 100 times larger than inactive) we should > + * become more permissive, or the system will take too much > + * cpu before it start swapping during memory pressure. > + * Distress is about avoiding early-oom, this is about > + * making swappiness graceful despite setting it to low > + * values. > + * > + * Avoid div by zero with nr_inactive+1, and max resulting > + * value is vm_total_pages. > + */ > + imbalance = zone_page_state(zone, NR_ACTIVE) / > + (zone_page_state(zone, NR_INACTIVE) + 1); > + > + /* > + * Reduce the effect of imbalance if swappiness is low, > + * this means for a swappiness very low, the imbalance > + * must be much higher than 100 for this logic to make > + * the difference. > + * > + * Max temporary value is vm_total_pages*100. > + */ > + imbalance *= (vm_swappiness + 1) / 100; ~~~~~~~~~~~~~~~~~~~~~~~~~ It will be zero! Better to scale it up before the division: imbalance *= (vm_swappiness + 1) * 1024 / 100; > + > + /* > + * If not much of the ram is mapped, makes the imbalance > + * less relevant, it's high priority we refill the inactive > + * list with mapped pages only in presence of high ratio of > + * mapped pages. > + * > + * Max temporary value is vm_total_pages*100. > + */ > + imbalance *= mapped_ratio / 100; imbalance *= mapped_ratio * 1024 / 100; > + /* apply imbalance feedback to swap_tendency */ > + swap_tendency += imbalance; swap_tendency += imbalance / 1024 / 1024; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org