Re: [PATCH 0/7] writeback: avoid touching dirtied_when on blockedinodes

[Wu Fengguang]

> In general it looks better we first root case the "decreasing wrote
> pages by writeback_single_inode() over time" problem before looking
> into further steps..

The problem shows up in many of the regression cases. For example,
the thresh=1G/ext4-100dd case with patches 1-4 applied will not only
see nr_writeback occasionally dropped low (bdi_dirty_state-8:0.png),
but also see repeated pattern of nr_wrote by writeback_single_inode()
slowly decreasing to 0 during some period of dozens of seconds
(writeback_single_inode.png).

Thanks,
Fengguang

Attachment: bdi_dirty_state-8:0.png
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Attachment: balance_dirty_pages-pages.png
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Attachment: writeback_single_inode.png
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