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Message-ID: <20100123160537.GG25842@discord.disaster> Date: Sun, 24 Jan 2010 03:05:37 +1100 From: Dave Chinner <david@...morbit.com> To: Andi Kleen <andi@...stfloor.org> Cc: Don Mullis <don.mullis@...il.com>, linux-kernel@...r.kernel.org, airlied@...hat.com, dedekind@...radead.org Subject: Re: [PATCH 1/2] lib: more scalable list_sort() On Sat, Jan 23, 2010 at 12:35:51PM +0100, Andi Kleen wrote: > > Burning CPU time to save on IO is a very valid tradeoff in > > filesystem design - burning a few hundred millieseconds of CPU > > time can result in savcwinge tens of seconds of IO time. Hence > > passing big long lists to be sorted is not an indication of broken > > design, it's an indication of understanding CPU time vs IO time > > tradeoffs during design... > > Burning long CPU time in kernel code without latency breaker code is always > a sign of broken design. It's a characteristic of a sub-optimal implementation, not bad design. Plenty of code has been fixed over the years simply by adding cond_resched() to loops that have triggered latency warnings. Similarly, adding cond_resched() to list_sort means you can stop worrying about the scheduling latency impact of sorting long lists. I fail to see why you're making such a big deal out of this..... Cheers Dave. -- Dave Chinner david@...morbit.com -- 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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