Messages in this thread | | | Subject | RE: [patch 0/3] no MAX_ARG_PAGES -v2 | Date | Wed, 13 Jun 2007 16:36:13 -0700 | From | "Luck, Tony" <> |
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> 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).
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