Re: Likley stupid question on "throttle_vm_writeout"

From: Peter Zijlstra
Date: Mon Nov 09 2009 - 10:26:44 EST


On Mon, 2009-11-09 at 07:15 -0800, Martin Knoblauch wrote:
> Hi, (please CC me on replies)
>
> I have a likely stupid question on the function "throttle_vm_writeout". Looking at the code I find:
>
> if (global_page_state(NR_UNSTABLE_NFS) +
> global_page_state(NR_WRITEBACK) <= dirty_thresh)
> break;
> congestion_wait(WRITE, HZ/10);
>
> Shouldn't the NR_FILE_DIRTY pages be considered as well?

Ha, you just trod onto a piece of ugly I'd totally forgotten about ;-)

The intent of throttle_vm_writeout() is to limit the total pages in
writeout and to wait for them to go-away.

Everybody hates the function, nobody managed to actually come up with
anything better.

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