Re: [PATCH] Warp speed building

[Jan Kiszka <jan.kiszka@web.de>]

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Luis R. Rodriguez wrote:
> On Tue, Jun 16, 2009 at 11:39 AM, Hauke Mehrtens<hauke@hauke-m.de> wrote:
>> Jan Kiszka wrote:
>>> Including config.mk again when kbuild called into the top level Makefile
>>> slowed down the build process awfully. The reason for this were all the
>>> dynamic, shell-based variable evaluations that were called over and over
>>> again. Fortunately, including config.mk only in the outer Makefile run
>>> appears to be enough. So let's remove this warp speed blocker.
>>>
>>> Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
>>> ---
>>>  Makefile |    2 --
>>>  1 files changed, 0 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/Makefile b/Makefile
>>> index 0ab7d27..49a786a 100644
>>> --- a/Makefile
>>> +++ b/Makefile
>>> @@ -13,8 +13,6 @@ OLD_IWL=$(shell $(MODPROBE) -l iwl4965)
>>>
>>>  ifneq ($(KERNELRELEASE),)
>>>
>>> -include $(M)/$(COMPAT_CONFIG)
>>> -
>>>  NOSTDINC_FLAGS := -I$(M)/include/ -include $(M)/include/net/compat.h $(CFLAGS)
>>>
>>>  obj-y := net/wireless/ net/mac80211/ net/rfkill/
>> Hi Jan,
>>
>> I have tested this patch and it reduced the build time for me from 3:30
>> to 2:40 minutes on a dual core system. I can not see any changes, expect
>> the reduced build time on my system. The resulting modules are still the
>> same.
> 
> Reason for including the config.mk is if your current kernel config
> differs the makefiles won't pick up the new stuff.

I had tested this before, and it did work nicely. To my understanding,
the 'export' in config.mk should carry all the defines into the nested
make calls.

Moreover, I'm surprised about this minimal reduction in Hauke's test.
Already running 'make clean' (no -j used for this) goes down from

    real    3m12.564s
    user    3m2.675s
    sys     0m8.461s

to

    real    0m20.670s
    user    0m17.337s
    sys     0m2.656s

here.

Jan


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