| Subject | Re: [PATCH 17/18] writeback: fix dirtied pages accounting on redirty | From | Peter Zijlstra <> | Date | Tue, 06 Sep 2011 18:18:56 +0200 |
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On Sun, 2011-09-04 at 09:53 +0800, Wu Fengguang wrote: > De-account the accumulative dirty counters on page redirty. > > Page redirties (very common in ext4) will introduce mismatch between > counters (a) and (b) > > a) NR_DIRTIED, BDI_DIRTIED, tsk->nr_dirtied > b) NR_WRITTEN, BDI_WRITTEN > > This will introduce systematic errors in balanced_rate and result in > dirty page position errors (ie. the dirty pages are no longer balanced > around the global/bdi setpoints). >
So wtf is ext4 doing? Shouldn't a page stay dirty until its written out?
That is, should we really frob around this behaviour or fix ext4 because its on crack?
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