Re: [RFC] [PATCH -mm 0/2] memcg: per cgroup dirty_ratio

From: KOSAKI Motohiro
Date: Wed Sep 24 2008 - 02:59:36 EST


> > We don't have any motivation of its interface change.
>
> We are seeing problems where we are generating a lot of dirty memory
> from asynchronous background writes while more important traffic is
> operating with DIRECT_IO. The DIRECT_IO traffic will incur high
> latency spikes as the pdflush hits the background threshold and tries
> to write a lot of dirty buffers at once.
>
> What we want to do is lower the background threshold low enough so
> that we don't end up writing a lot of data at one time. As systems get
> more and more memory this is and will become difficult. 1% of system
> RAM could tie up a disk.

yup.
sorry, I choosed bad word at my last mail. it caused your confusion.
I only disagreed vm_dirty_KB.

I agreed with fine graind vm_dirty_ratio.

Thanks.


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