Re: [ccache] Theoretical question regarding ccache

2017-04-29 Thread Anders Björklund via ccache
Aashaka Shah wrote:

> I recently came across ccache as I have an assignment to think of a novel
> compiler design or related problem, and having a cache for compilers was
> the first thing that came to my mind. I thought of trying it out on
> QuantLib, a financial computation library.

Hi! It would interesting to have some more scientific research on this,
since ccache is a rather pragmatic project. It's "memoization", I think.

> I would like to know
> 
> 1. Why multiple source files cannot take advantage of ccache ( Why other
> types of compilations (multi-file compilation, linking, etc) will silently
> fall back to running the real compiler)

Well, depends on what you mean with "source" exactly. Basically when you
have one source (.c), it would still read a lot of headers (.h) etc...

But when you give the compiler more than one C/C++ source file, it will
compile them one by one anyway. Looks like your build system is broken ?


Do you have an example of the actual files you are trying to compile ?

It would help when trying to understand what you are trying to do here.


> 2. Where in the memory hierarchy(cache, main memory?) does the ccache
> output reside? Does it work according to the default replacement policies
> of the hardware cache?

The ccache files are stored on the filesystem, so in the "secondary" ?
Usually it's stored in RAM and written to disk, unless using a ramdisk.

Using the memcached implementation also offers you other mixed options.
https://en.wikipedia.org/wiki/Memcached (see the dev/memcached branch)

/Anders
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[ccache] Theoretical question regarding ccache

2017-04-29 Thread Aashaka Shah via ccache
Hi,

I recently came across ccache as I have an assignment to think of a novel
compiler design or related problem, and having a cache for compilers was
the first thing that came to my mind. I thought of trying it out on
QuantLib, a financial computation library.

I would like to know

1. Why multiple source files cannot take advantage of ccache ( Why other
types of compilations (multi-file compilation, linking, etc) will silently
fall back to running the real compiler)
2. Where in the memory hierarchy(cache, main memory?) does the ccache
output reside? Does it work according to the default replacement policies
of the hardware cache?

Thanks for your patience in reading this through!

Regards,
Aashaka
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