Re: per-bdi-throttling: synchronous writepage doesn't workcorrectly

From: Peter Zijlstra
Date: Thu Nov 01 2007 - 12:51:41 EST


On Thu, 2007-11-01 at 17:49 +0100, Miklos Szeredi wrote:
> Hi,
>
> It looks like bdi_thresh will always be zero if filesystem does
> synchronous writepage, resulting in very poor write performance.
>
> Hostfs (UML) is one such example, but there might be others.
>
> The only solution I can think of is to add a set_page_writeback();
> end_page_writeback() pair (or some reduced variant, that only does
> the proportions magic). But that means auditing quite a few
> filesystems...

Ouch...

I take it there is no other function that is shared between all these
writeout paths which we could stick a bdi_writeout_inc(bdi) in?


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