Re: [ext3][kernels >= 2.6.20.7 at least] KDE going comatose whenFS is under heavy write load (massive starvation)

From: Marko Macek
Date: Fri Apr 27 2007 - 15:46:09 EST


Linus Torvalds wrote:

On Fri, 27 Apr 2007, John Anthony Kazos Jr. wrote:
Could[/should] this stuff be changed from ratios to amounts? Or a quick boot-time test to use a ratio if the memory is small and an amount (like tax brackets, I would expect) if it's great?

Yes, the "percentage" thing was likely wrong. That said, there *is* some correlation between "lots of memory" and "high-end machine", and that in turn tends to correlate with "fast disk", so I don't think the percentage approach is really *horribly* wrong.

The main issue with the percentage is that we do export them as such through the /proc/ interface, and they are easy to change and understand. So changing them to amounts is non-trivial if you also want to support the old interfaces - and the advantage isn't obvious enough that it's a clear-cut case.

I wonder if it would be useful if the limit was 'data we can write out in 1 (configurable) second. This would typically mean either one 50mb (depending on disk) contigous block or 100-200 scattered blocks (since the typical disk latency is about 5-10ms).

Has anyone tried something like this?

Mark
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