Date: Sun, 14 Jul 1996 14:49:39 +1000 (EST) From: michael butler <imb@asstdc.com.au> To: hasty@rah.star-gate.com (Amancio Hasty) Cc: hackers@freebsd.org Subject: Re: Kernel Config (Was: GENERIC Kernel Debate) Message-ID: <199607140449.OAA00418@walkabout.asstdc.com.au> In-Reply-To: <199607140320.UAA00618@rah.star-gate.com> from Amancio Hasty at "Jul 13, 96 08:20:51 pm"
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> The issue of 30minutes for a kernel compile has got to be due > to gcc . Not sure what changed between gcc-1.42 and and gcc-2.x however > simple minded experiments have shown that gcc-2.x takes about 3 times > longer to compile. I feel that one-time compilation overheads are the last on the list of priorities when you want a kernel that performs reasonably well. If you want faster compilation, simply remove the "-O". You can have it one way or the other; both is not (currently) an option. > The other major factor is the cpu/disk/controller and > if you have a minimally configured system, memory is important. On a machine with enough memory, you can add "-pipe" to both CFLAGS-like options in /etc/make.conf. In fact, I use "-m486 -O2 -pipe" on all my "production" kernels and binaries (noting, for the less up-to-date, that 2.1-R also requires "-fno-strength-reduce" for "correct" code generation). Having transitioned my own networks from Interactive SVR3.2, it should be noted that the reason why SysV-derived systems allow "quick" compilation of new user configurations is that (almost) the only things they translate are the "space.c" files containing tables (plain data) referencing the object code stored in one or more system libraries (since you don't get the source-code). The compiler used doesn't for this have to be fancy .. no amount of optimisation is likely to have any impact on a data-only structure. Greater flexibility and performance has its price .. IMHO it's well worth the one-time overhead, michael
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