[U-Boot] [U-Boot, 1/2] common: Add CCACHE variable to allow use of ccache

[sun york-R58495]

On Aug 21, 2013, at 10:45 PM, sun york-R58495 wrote:

> 
> On Aug 21, 2013, at 10:02 PM, Marek Vasut wrote:
> 
>> Dear sun york-R58495,
>> 
>>> On Aug 21, 2013, at 7:51 PM, Marek Vasut wrote:
>>>> Dear York Sun,
>>>> 
>>>>> On 05/20/2013 10:25 AM, Marek Vasut wrote:
>>>>>> Prefix HOSTCC and CC with CCACHE variable to allow easy use of ccache.
>>>>>> In case the user wants to use ccache, exporting CCACHE=ccache will do
>>>>>> the trick. It is of course possible to either make the cross-compiler
>>>>>> name into a shellscript which invokes the ccache and the compiler, but
>>>>>> setting this variable makes use of ccache easier and more convenient.
>>>>>> 
>>>>>> Using ccache becomes convenient when using MAKEALL for large build
>>>>>> tests, where the speedup after building the cache for the first time
>>>>>> is about 4-6 times.
>>>>>> 
>>>>>> Signed-off-by: Marek Vasut <marex at denx.de>
>>>>>> Cc: Tom Rini <trini at ti.com>
>>>>>> 
>>>>>> ---
>>>>>> config.mk |    8 +++++---
>>>>>> 
>>>>>> 1 file changed, 5 insertions(+), 3 deletions(-)
>>>>>> 
>>>>>> diff --git a/config.mk b/config.mk
>>>>>> index 1fd109f..d59ded2 100644
>>>>>> --- a/config.mk
>>>>>> +++ b/config.mk
>>>>>> @@ -98,6 +98,8 @@ else
>>>>>> 
>>>>>> HOSTCC		= gcc
>>>>>> endif
>>>>>> 
>>>>>> +HOSTCC		:= $(CCACHE) $(HOSTCC)
>>>>>> +
>>>>>> 
>>>>>> ifeq ($(HOSTOS),cygwin)
>>>>>> HOSTCFLAGS	+= -ansi
>>>>>> endif
>>>>>> 
>>>>>> @@ -140,13 +142,13 @@ binutils-version = $(shell $(SHELL)
>>>>>> $(SRCTREE)/tools/binutils-version.sh $(AS))
>>>>>> 
>>>>>> #
>>>>>> # Include the make variables (CC, etc...)
>>>>>> #
>>>>>> 
>>>>>> -AS	= $(CROSS_COMPILE)as
>>>>>> +AS	= $(CCACHE) $(CROSS_COMPILE)as
>>>>>> 
>>>>>> # Always use GNU ld
>>>>>> LD	= $(shell if $(CROSS_COMPILE)ld.bfd -v > /dev/null 2>&1; \
>>>>>> 
>>>>>> 		then echo "$(CROSS_COMPILE)ld.bfd"; else echo
>>>> 
>>>> "$(CROSS_COMPILE)ld";
>>>> 
>>>>>> 		fi;)
>>>>>> 
>>>>>> -CC	= $(CROSS_COMPILE)gcc
>>>>>> +CC	= $(CCACHE) $(CROSS_COMPILE)gcc
>>>>>> 
>>>>>> CPP	= $(CC) -E
>>>>>> AR	= $(CROSS_COMPILE)ar
>>>>>> NM	= $(CROSS_COMPILE)nm
>>>>>> 
>>>>>> @@ -320,7 +322,7 @@ endif
>>>>>> 
>>>>>> #######################################################################
>>>>>> # #
>>>>>> 
>>>>>> -export	HOSTCC HOSTCFLAGS HOSTLDFLAGS PEDCFLAGS HOSTSTRIP CROSS_COMPILE
>>>> 
>>>> \
>>>> 
>>>>>> +export	HOSTCC HOSTCFLAGS HOSTLDFLAGS PEDCFLAGS HOSTSTRIP CROSS_COMPILE
>>>>>> CCACHE \
>>>>>> 
>>>>>> 	AS LD CC CPP AR NM STRIP OBJCOPY OBJDUMP MAKE
>>>>>> 
>>>>>> export	CONFIG_SYS_TEXT_BASE PLATFORM_CPPFLAGS PLATFORM_RELFLAGS
>>>> 
>>>> CPPFLAGS
>>>> 
>>>>>> CFLAGS AFLAGS
>>>>> 
>>>>> Where did this patch go? I found it useful.
>>>> 
>>>> It needs additional fixes, try running with MAKEALL and you will see the
>>>> problem -- the problem is you would need separate ccache for each
>>>> MAKEALL thread.
>>> 
>>> I didn't use this patch but I modified config.mk as this patch did. MAKEALL
>>> works fine for "-a powerpc". It cuts my compiling time more than half for
>>> 660+ boards.
>> 
>> That is still poor, it should be much faster. If you use separate ccache for 
>> each board, then it will be _much_ more performant.
>> 
>> The problem is that when rebuilding all of those 680 configurations, the cached 
>> files get replaced by ones based on different board config all the time => you 
>> need to rebuild them => you loose performance.
>> 
> 
> I kind of get it. I have to increase my ccache size a lot (more than 2GB) to get consistent cache hit. I thought that was because I was using out-of-tree build when setting BUILD_NBUILDS. For the first time I run MAKEALL with ccache, it was completely miss. I mean zero hit. It would be nice to be able hit the cache. I was read the ccache document to understand how the path is involved when calculating the hash. How do you plan to make it work?
> 
I forgot to mention, if the ccache size is at default (1GB), I don't see any performance improvement by using ccache. I think that's what you meant the cached files get replaced. I don't understand what you mean to use separated ccache for each board. Would it be equivalent to have a big cache? I was compiling with and without BUILD_NBUILDS, and my cache size is more than 3GB now. I could see the improvement by 2x~3x faster, but not more. 

York