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Date: Wed, 13 Jun 2007 16:36:13 -0700 From: "Luck, Tony" <tony.luck@...el.com> To: "Peter Zijlstra" <a.p.zijlstra@...llo.nl>, <linux-kernel@...r.kernel.org>, <parisc-linux@...ts.parisc-linux.org>, <linux-mm@...ck.org>, <linux-arch@...r.kernel.org> Cc: "Ollie Wild" <aaw@...gle.com>, "Andrew Morton" <akpm@...l.org>, "Ingo Molnar" <mingo@...e.hu>, "Andi Kleen" <ak@...e.de> Subject: RE: [patch 0/3] no MAX_ARG_PAGES -v2 > This patch-set aims at removing the current limit on argv+env space aka. > MAX_ARG_PAGES. Running with this patch shows that /bin/bash has some unpleasant O(n^2) performance issues with long argument lists. I made a 1Mbyte file full of pathnames, then timed the execution of: $ /bin/echo `cat megabyte` | wc $ /bin/echo `cat megabyte megabyte` | wc etc. ... System time was pretty much linear as the arglist grew (and only got up to 0.144 seconds at 5Mbytes). But user time ~= real time (in seconds) looks like: 1 5.318 2 18.871 3 40.620 4 70.819 5 108.911 Above 5Mbytes, I started seeing problems. The line/word/char counts from "wc" started being "0 0 0". Not sure if this is a problem in "wc" dealing with a single line >5MBytes, or some other problem (possibly I was exceeding the per-process stack limit which is only 8MB on that machine). -Tony - 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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