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Date: Wed, 31 Dec 2008 09:08:26 -0700 From: "Peter W. Morreale" <pmorreale@...ell.com> To: Andi Kleen <andi@...stfloor.org> Cc: linux-kernel@...r.kernel.org Subject: Re: [PATCH 0/2] pdflush fix and enhancement On Wed, 2008-12-31 at 14:27 +0100, Andi Kleen wrote: > > I say most because the assumption would be that we will be successful in > > creating the new thread. Not that bad an assumption I think. Besides, > > And that the memory read is not reordered (rmb()). > At the risk of showing my b*tt here... I'm not very clear on memory barriers, is this necessary even inside a critical region? (recall we're protected by the spin lock). If so, does the barrier go after the read, or before? (Thanks for not laughing, however grins are allowed) > > Ok it probably needs some kind of feedback mechanism. > Actually, I tend to think we need an entirely different approach to flushing, please see my post to David Chinner which outlines some thoughts. Basically a flushing heuristic that takes into account the characteristics of the various block devices. > > > > I was thinking about a patch that would go both directions - forward and > > reverse depending upon, say, a bit in jiffies... Certainly not perfect, > > but a bit more fair. > > Better a real RNG. But such probalistic schemes unfortunately tend to drive > benchmarkers crazy, that is why it is better to avoid them. > Nod, but that's ok. Having been one for several years I can truthfully say that benchmarkers are a little crazy anyways... :-) > I suppose you could just keep some state per fs to ensure fairness. > Nod, this would be ideal. -PWM > -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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