is ccache working effectively?

[Maurizio Cimadamore]

On 20/11/2018 11:49, Magnus Ihse Bursie wrote:
> 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?

That sounds like a good idea

Maurizio

>
> /Magnus
>>
>> 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 :-)
>>
>> Maurizio
>>
>> 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.
>>>
>>> /Erik
>>>
>>>
>>> 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:
>>>>
>>>> build/<CONF>/hotspot/variant-server/libjvm/objs/precompiled
>>>>
>>>> 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.
>>>>
>>>> Maurizio
>>>>
>>>
>