Messages in this thread | | | Date | Thu, 05 Jan 2006 18:47:22 +0900 | From | IWAMOTO Toshihiro <> | Subject | Re: [PATCH 6/9] clockpro-clockpro.patch |
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At Sat, 31 Dec 2005 12:29:06 +0100, Peter Zijlstra wrote: > > Forgot one in the previous mail. > > On Fri, 2005-12-30 at 22:24 -0200, Marcelo Tosatti wrote: > > Please make it easier for others to understand why the hands > > swap, and when, and why. > > Its not the hands that swap, its the lists. The hands will lap each > other, like the minute hand will lap the hour hand every ~65 minutes. > > Let me try some ascii art. > > ==== > ^---<>---v > ==== > > '=' a page > '^---<' hand cold > '>---v' hand hot > > now let hand cold move 4 pages: > > > ^---<>---v > ======== > > ie. hand hot and hand cold have the same position. > now if we want to move hand cold one more position this happens: > > ======= > ^---<>---v > = > > see the swap?
Is it okay to allow Hcold to lap Hhot? In my understanding of CLOCK-Pro, such lapping causes sudden increase in the distance between Hhot and Hcold. As that distance is an important parameter of page aging/replacement decisions, I'm afraid that such lapping would result in incorrect page aging and bad performance.
I guess the alternative is to advance Hhot together with Hcold, but I'm not sure this is correct, either.
Please enlighten me.
-- IWAMOTO Toshihiro - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.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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