Date: Sun, 11 Mar 2001 15:40:21 -0500 From: Donn Miller <dmmiller@cvzoom.net> To: Roman Shterenzon <roman@harmonic.co.il> Cc: Matt Dillon <dillon@earth.backplane.com>, "freebsd-stable@FreeBSD.ORG" <freebsd-stable@FreeBSD.ORG> Subject: Re: ARCH flag in new make.conf Message-ID: <3AABE2B5.D808C4E0@cvzoom.net> References: <Pine.LNX.4.10.10103111145220.18158-100000@shark.harmonic.co.il>
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Roman Shterenzon wrote: > > Just wanted to say that for RELENG_3 with gcc 2.7.2.3 or whatever it was, > -O2 worked just fine for me (both kernel and userland, I stopped building > userland with -O2 since 3.3 because it took much more time to build world). > Also, linux that used the same gcc always built kernel with -O2. > So, I believe that 2.95.2 is the one that having the problems. I think that in the case of the FreeBSD kernel or userland, anything about -O will not help much at all. The userland code is pretty much optimized and streamlined as much as possible, i.e., register variables are spec'd whenever possible. -O2 helps significantly whenever you have a lot of very large loops, and I'm not so sure the world+kernel source code has lots of very large and numerous for and while loops. Plus, it prolongs the buildworld time. -O3 just inlines functions wheverever possible, bloating things. Also, I've noticed subtle problems with gcc and tools when I've built world with anything higher than -O. For example, when gcc is built with -O2 or -Os, I've noticed that it starts acting a little quirky, e.g., eating up large amounts of memory. Building world with -O fixes this. XFree86 4-current has problems with pthreads whenever you build the code with -O3, i.e., I get "undefined reference to [some pthread function]". Dropping back to -O2 fixes this. BTW, XFree86 4-current supports threading on FreeBSD now by default, right "out of the box". It's about time! Thank you, thank you, whomever committed those changes. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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