Re: ll_rw_block/submit_bh and request limits

From: Marcelo Tosatti (marcelo@conectiva.com.br)
Date: Thu Feb 22 2001 - 15:40:48 EST


On Thu, 22 Feb 2001, Andrea Arcangeli wrote:

> On Thu, Feb 22, 2001 at 10:59:20AM -0800, Linus Torvalds wrote:
> > I'd prefer for this check to be a per-queue one.
>
> I'm running this in my tree since a few weeks, however I never had the courage
> to post it publically because I didn't benchmarked it carefully yet and I
> prefer to finish another thing first.

You want to throttle IO if the amount of on flight data is higher than
a given percentage of _main memory_.

As far as I can see, your patch avoids each individual queue from being
bigger than the high watermark (which is a percentage of main
memory). However, you do not avoid multiple queues together from being
bigger than the high watermark.

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This archive was generated by hypermail 2b29 : Fri Feb 23 2001 - 21:00:28 EST