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 <ma...@denx.de> >>>>>> Cc: Tom Rini <tr...@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.
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