Date: Mon, 24 Nov 2003 22:30:39 -0800 From: Gordon Tetlow <gordont@gnf.org> To: freebsd-current@freebsd.org Subject: Re: 40% slowdown with dynamic /bin/sh Message-ID: <20031125063039.GB53437@roark.gnf.org> In-Reply-To: <16322.46739.544236.261395@grasshopper.cs.duke.edu> References: <200311250106.hAP16qNp018512@realtime.exit.com> <200311251212.59933.doconnor@gsoft.com.au> <16322.46739.544236.261395@grasshopper.cs.duke.edu>
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--U+BazGySraz5kW0T Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Nov 24, 2003 at 08:55:31PM -0500, Andrew Gallatin wrote: >=20 > Daniel O'Connor writes: >=20 > > Why didn't you pipe up when this was discussed _long_ ago? >=20 > In the orginal thread, there was an agreement that the performance > would be measured BEFORE the default was changed, and the default > would only be changed if there was no measurable performance impact. > I believe sam@ asked for this. As far as I know, performance > measurments were never done. Instead, the switch was thrown just > before the code freeze. That's not true. I was asked to present numbers so we could make a determination as to what the impact was. It was never said that it would only be the default iff there was no performance impact. FWIW, I did find that the boot process took a performance hit, I also found that the average worldstone did not increase appreciably (ie, less than 1%). I took these numbers to re@ when I was asked to flip the dynamic switch and the feeling was that the overhead was worth the tradeoff for functionality. Finally, I must ask if anyone has evidence that this has slowed down anything other than microbenchmarks? My point of view was it did slow down the boot, but so did rcNG and no one seemed to mind about that. Also, you don't write time-sensitive applications in shell so the dynamic link overhead is not noticed there. People asked me about the affect on periodic. My response is why do you care if your periodic took 1 extra second to run (on the outside) due to dynamic linking overhead. It's just crazy. In summary, I have yet to see a compelling arguement to consider backing out the dynamic linking changes I've put in. I've read all of the messages in all of the 3+ huge threads and I'm still as resolved today as I was when I made the commit. Frankly, I'm surprised people didn't yell at me when I massively restructured the tree to put libraries in /lib. Turning on dynamic linking was the most minor part from the architectural point of view but is getting the most vitriol. How typical. -gordon --U+BazGySraz5kW0T Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.2 (FreeBSD) iD8DBQE/wvcPRu2t9DV9ZfsRAs1qAKCnEtOJndkrejz2nNzDB9GBIcAdcgCfTWNz R5Y6gK3P4+VRAQV/xEapnG8= =Ru7w -----END PGP SIGNATURE----- --U+BazGySraz5kW0T--
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