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From "Aleksey Shipilev (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HARMONY-5356) [drlvm][startup][performance] Delayed recompilation implementation
Date Fri, 11 Jan 2008 10:06:34 GMT

    [ https://issues.apache.org/jira/browse/HARMONY-5356?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12557954#action_12557954
] 

Aleksey Shipilev commented on HARMONY-5356:
-------------------------------------------

Mikhail, it's used in 
   pc = new DelayProfileCollector(this, profilerName, step->jit, initialTimeout, delayTimeout);

That's the place to optimize. My thought was it works like this: we specify delayTimeout as
tick interval, and then making tick-tack with method tables (on current tick all new methods
coming to be registered, all previously registered methods are notified). Even though it's
not guaranteed each method will be delayed for exact delayTimeout, this approach is simple
and solves the problem I described.


> [drlvm][startup][performance] Delayed recompilation implementation
> ------------------------------------------------------------------
>
>                 Key: HARMONY-5356
>                 URL: https://issues.apache.org/jira/browse/HARMONY-5356
>             Project: Harmony
>          Issue Type: Sub-task
>            Reporter: Aleksey Shipilev
>         Attachments: vm-delayprofiler-1.patch
>
>
> Now, client JIT chains look like this:
> chains=chain1,chain2
> chain1.jits=JET_CLINIT
> chain2.jits=JET_DPGO,CD_OPT
> chain1.filter=+::<clinit>
> chain1.filter=-
> JET_CLINIT.file=jitrino
> JET_DPGO.file=jitrino
> CD_OPT.file=jitrino
> JET_DPGO.genProfile=EB_PROF
> EB_PROF.profilerType=EB_PROFILER
> CD_OPT.useProfile=EB_PROF
> So, all methods (except constructors) are passing through JET_DPGO with EB_PROF attached
and then will be recompiled by CD_OPT. One should note that this will cause concurrency between
on-going _recompilation_ and first-time JET compilation. So, if first-time JET compilation
speed is important for startup, then we should separate these two processes in time. That
is, let's compile all in the bunch with JET and only then start to recompile with OPT.
> That is, we can either:
>  a. Set the thresholds for EB_PROF such as recompilation would held later
>  b. Introduce new step (e.g. JET_QUICK) which would compile really fast (even without
profile) and wait before inducing recompilation. 
> Current architecture of Jitrino requires some profiler to do the notification for traversing
the JITs chain, so attached patch introduces dummy DELAY_PROFILER which simply waits desired
time. 
> So, we will have:
> chains=chain1,chain2
> chain1.jits=JET_CLINIT
> chain2.jits=JET_QUICK,JET_DPGO,CD_OPT
> chain1.filter=+::<clinit>
> chain1.filter=-
> JET_CLINIT.file=jitrino
> JET_QUICK.file=jitrino
> JET_DPGO.file=jitrino
> CD_OPT.file=jitrino
> JET_DPGO.genProfile=EB_PROF
> EB_PROF.profilerType=EB_PROFILER
> CD_OPT.useProfile=EB_PROF
> JET_QUICK.genProfile=DL_PROF
> DL_PROF.profilerType=DL_PROFILER
> DL_PROF.initialTimeout=0
> DL_PROF.delayTimeout=100

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