Re: [gentoo-dev] Re: RFC: --as-needed to default LDFLAGS
Ulrich Mueller a écrit : Speaking about statistics: Either I have missed it, or so far nobody has presented any solid numbers showing what the benefit of --as-needed in terms of memory usage or program startup time is. The reduction in startup time may not be noticeable. The real win is when low level libs change ABI, like expat. On a standard Gnome system, without --as-needed, I had over 280 packages to rebuild (that was a very slow Duron 700Mhz, I ended up moving to --as-needed and did emerge -e world). On my other box which had had --as-needed for a while (so some useless rebuild could have been further avoided), I only had around 45 packages. And for the sake of the thread, had libtool been smarter, I'm sure that the final number could have gone down to 20 or so packages. My opinion: - we need --as-needed because it's useful (maybe ld could echo the libs that's it's dropping and then we could have a QA warning?) - we *do* need to fix libtool too - we need to make sure upstream packages provide correct .pc files Just a thought :) Rémi -- gentoo-dev@lists.gentoo.org mailing list
[gentoo-dev] Re: RFC: --as-needed to default LDFLAGS (Was: RFC: Should preserve-libs be enabled by default?)
Ciaran McCreesh [EMAIL PROTECTED] posted [EMAIL PROTECTED], excerpted below, on Sat, 31 May 2008 04:03:38 +0100: The correct fix is to make libtool only link to dependencies of dependencies when doing, for example, static linking. Debian has a half-working patch for this that I posted earlier in the thread. Thanks. That explanation (mostly snipped for brevity) was a great plain English explanation for those of us trying to follow along but not making any claim to be great programmers or at understanding the depths of libtool. -- Duncan - List replies preferred. No HTML msgs. Every nonfree program has a lord, a master -- and if you use the program, he is your master. Richard Stallman -- gentoo-dev@lists.gentoo.org mailing list
[gentoo-dev] Re: RFC: --as-needed to default LDFLAGS
[Answering to some random message in this long thread.] On Sat, 31 May 2008, Brian Harring wrote: So... folks have pointed out a benefit to using --as-needed. The benefit itself doesn't seem particularly in dispute, analyze the fallout from it- if the best that is offered is the spec says otherwise, screw the spec frankly- a .01% breakage w/ 99.99% pkgs getting a positive gain is a strong argument for doing exemptions where needed. Speaking about statistics: Either I have missed it, or so far nobody has presented any solid numbers showing what the benefit of --as-needed in terms of memory usage or program startup time is. Could someone please show this comparison for some common programs? I've just done this for Emacs (22.2-r2), virtual set size directly after startup is 25280 and 25276 kB, for Emacs built without and with --as-needed, respectively (resident set size is 14412 and 14396 kB). I don't see any difference in startup time. But maybe Emacs is an uncommon application, or I am looking for the wrong things? Could one of the experts please shed some light on this? Ulrich -- gentoo-dev@lists.gentoo.org mailing list
Re: [gentoo-dev] Re: RFC: --as-needed to default LDFLAGS
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Ulrich Mueller wrote: | But maybe Emacs is an uncommon application, or I am looking for the | wrong things? Could one of the experts please shed some light on this? I think you're looking for the wrong things. I'm not an expert, but I think --as-needed means that if there are 20 libraries on your system that use libexpat.so.0 and 400 programs that use those 20 libraries, when libexpat is updated to libexpat.so.1, you only need to rebuild the 20 libraries, not all 420 packages (as you would do otherwise). I believe that's the main reason for using as-needed... Mike 5:) -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.9 (GNU/Linux) iEYEARECAAYFAkhBp9oACgkQu7rWomwgFXr8JQCfYFDwcebduPVaY3yqUIEfVOxp G80AoKV6SsAewxyyfv+fsiwbc6M1BHsc =12e5 -END PGP SIGNATURE- -- gentoo-dev@lists.gentoo.org mailing list
[gentoo-dev] Re: RFC: --as-needed to default LDFLAGS
Mike Auty [EMAIL PROTECTED] posted [EMAIL PROTECTED], excerpted below, on Sat, 31 May 2008 20:32:42 +0100: I think you're looking for the wrong things. I'm not an expert, but I think --as-needed means that if there are 20 libraries on your system that use libexpat.so.0 and 400 programs that use those 20 libraries, when libexpat is updated to libexpat.so.1, you only need to rebuild the 20 libraries, not all 420 packages (as you would do otherwise). I believe that's the main reason for using as-needed... That has certainly been my experience. I've had way less rebuilds to worry about since I added that to my LDFLAGS and rebuilt the system. revdep-rebuild -p, which I run regularly after major world upgrades, returns far fewer packages to rebuild, now. -- Duncan - List replies preferred. No HTML msgs. Every nonfree program has a lord, a master -- and if you use the program, he is your master. Richard Stallman -- gentoo-dev@lists.gentoo.org mailing list
