How to change compilation policy to trigger C2 compilation ASAP?

Zoltán Majó zoltan.majo at oracle.com
Wed May 20 06:47:17 UTC 2015


Hi Wei,


On 05/20/2015 03:12 AM, Vladimir Kozlov wrote:
[...]
> An other approach is to set threshold per method (scale all 
> threasholds (C1, C2, interpreter) by this value). For example to 
> reduce thresholds by half:
>
> -XX:CompileCommand=option,SomeClass.someMethod,double,CompileThresholdScaling,0.5 
>

just to complement what Vladimir suggested: If you want to scale 
thresholds for all methods at once, the CompileThresholdScaling can be 
also used globally. For example, -XX:CompileThresholdScaling=0.5 would 
reduce all thresholds by half (both with tiered and non-tiered modes of 
operation).

Best regards,


Zoltan

>
> Vladimir
>
> On 5/19/15 5:43 PM, Tangwei (Euler) wrote:
>> My goal is just to reach peak performance quickly. Following is one tier
>> threshold combination I tried:
>>
>> -XX:Tier0ProfilingStartPercentage=0
>>
>> -XX:Tier3InvocationThreshold=3
>>
>> -XX:Tier3MinInvocationThreshold=2
>>
>> -XX:Tier3CompileThreshold=2
>>
>> -XX:Tier4InvocationThreshold=4
>>
>> -XX:Tier4MinInvocationThreshold=3
>>
>> -XX:Tier4CompileThreshold=2
>>
>> Regards!
>>
>> wei
>>
>> *From:*Vitaly Davidovich [mailto:vitalyd at gmail.com]
>> *Sent:* Tuesday, May 19, 2015 9:33 PM
>> *To:* Tangwei (Euler)
>> *Cc:* hotspot compiler
>> *Subject:* Re: How to change compilation policy to trigger C2
>> compilation ASAP?
>>
>> Is your goal specifically to have C2 compile or just to reach peak
>> performance quickly? It sounds like the latter.  What values did you
>> specify for the tier thresholds? Also, it may help you to
>> -XX:+PrintCompilation to tune the flags as this will show you which
>> methods are being compiled, when, and at what tier.
>>
>> sent from my phone
>>
>> On May 19, 2015 9:01 AM, "Tangwei (Euler)" <tangwei6 at huawei.com
>> <mailto:tangwei6 at huawei.com>> wrote:
>>
>> Hi All,
>>
>>    I want to run a JAVA application on a performance simulator, and do a
>> profiling on a hot function JITTed with C2 compiler.
>>
>> In order to make C2 compiler compile hot function as early as possible,
>> I hope to reduce the threshold of function invocation
>>
>> count in interpreter and C1 to drive the JIT compiler transitioned to
>> Level 4 (C2) ASAP. Following is the option list I try, but
>>
>> failed to find a right combination to meet my requirement. Anyone can
>> help to figure out what options I can use?
>>
>> Thanks in advance.
>>
>> -XX:Tier0ProfilingStartPercentage=0
>>
>> -XX:Tier3InvocationThreshold
>>
>> -XX:Tier3MinInvocationThreshold
>>
>> -XX:Tier3CompileThreshold
>>
>> -XX:Tier4InvocationThreshold
>>
>> -XX:CompileThreshold
>>
>> -XX:Tier4MinInvocationThreshold
>>
>> -XX:Tier4CompileThreshold
>>
>> Regards!
>>
>> wei
>>



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