RFR: JDK-8027584 disable ccache by default

[Magnus Ihse Bursie]

On 2014-01-29 01:44, Mike Duigou wrote:
> Looks fine. (I have been caught by the Windows cygwin issue as well).
>
> Do you want to do away with the performance hints entirely? I had another patch for setting memsize which added other hints.
Yes, I thought we should remove it entirely. I've heard people complain 
about the .hide-performance-hints file it creates, and frankly, there's 
probably too much information already in the configure output -- I don't 
think anyone really reads it. Fredrik put up the hint long time ago, 
before we started seeing all these issues with ccache, and I was not 
courageous enogh to remove it earlier. :-)

But if you have another patch that relies on it, I'll either leave it in 
place, or you'll have to resurrect it later.

Maybe it would be better to have a separate way to answer the question 
"how can I increase build performance"? Maybe some kind of tool that 
analyses common performance issues with the machine and/or the 
configuration? Rather than to put a lot of output from configure, where 
even the important stuff drowns...

/Magnus

>
> Mike
>
> On Jan 28 2014, at 15:31 , Magnus Ihse Bursie <magnus.ihse.bursie at oracle.com> wrote:
>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8027584
>>
>> While ccache can be used to speed up recompilations, there are also several issues with ccache. Old versions does not work correctly for the jdk (we try to detect that). It does not work well on other platforms than Linux; on Windows it does not work at all. Nevertheless is ccache enabled on Windows if it is installed, which it apparently tends to be with Cygwin nowadays, requiring the use of --disable-ccache to avoid compilation failure.
>>
>> In many circumstances ccache also does not provide any performance benefit. For instance, new compilations gets a performance hit. Only recompilations benefits.
>>
>> It is better to turn this upside down. This patch makes ccache disabled by default, on all platforms. If you want ccache and are sure you are in a situation that benefits from it, then you can enable it. It also removes the output in configure hinting that ccache should be used.
>>
>> WebRev: http://cr.openjdk.java.net/~ihse/JDK-8027584-disable-ccache-by-default/webrev.01
>>
>> /Magnus