is ccache working effectively?
Magnus Ihse Bursie
magnus.ihse.bursie at oracle.com
Tue Nov 20 11:49:06 UTC 2018
On 2018-11-09 11:09, Maurizio Cimadamore wrote:
> That does the trick, thanks.
If ccache and PCH is so bad in combination, maybe we should not allow
it? Like turning off PCH by default of --enacle-ccache is given? Or at
least *warn* that this combination is no good?
> I take a very small hit in the cold cache case, but then I get huge
> boost once the cache is hot.
> cache hit (direct) 1629
> cache hit (preprocessed) 115
> cache miss 1
> cache hit rate 99.94 %
> cleanups performed 0
> files in cache 5121
> cache size 317.6 MB
> max cache size 5.0 GB
> And, in my laptop the clean/build time went down from 11 mins to 3 :-)
> On 09/11/2018 00:24, Erik Joelsson wrote:
>> You can try --disable-precompiled-headers and see if that helps. We
>> have had special considerations for combining these features in the
>> past, but it's certainly a source of trouble for ccache.
>> On 2018-11-08 16:20, Maurizio Cimadamore wrote:
>>> On 08/11/2018 20:31, Erik Joelsson wrote:
>>>> I think we need more details here to figure it out, but it doesn't
>>>> surprise me that hotspot is the part that's failing. Building
>>>> hotspot is way more complex than the rest.
>>> Digging more into the command lines of the various HS files, they
>>> include many generated sources and, also this folder:
>>> Now, I don't know exactly how ccache deals with PCH but I notices
>>> that every time that the files in this folder are regenerated by the
>>> build (I can easily do that by rerunning the same command line that
>>> is stored inside the , a ccache miss follows.
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