RFR(M): 8194258: PPC64 safepoint mechanism: Fix initialization on AIX and support SIGTRAP
Robbin Ehn
robbin.ehn at oracle.com
Fri Dec 29 11:50:00 UTC 2017
Hi Martin,
Looks fine!
/Robbin
On 2017-12-28 18:47, Doerr, Martin wrote:
> Hi,
>
> unfortunately, the safepoint mechanism initialization on AIX is not completely correct, yet. The VM crashes when using -XX:-OptimizePollingPageLocation or when allocation at desired addresses failed.
>
> Only pages allocated by mmap can be read protected.
>
> In addition, SIGTRAP-based polling performs slightly better on PPC64 and avoids the need for allocating a protected page.
>
> I have uploaded a webrev:
>
> http://cr.openjdk.java.net/~mdoerr/8194258_PPC64_poll/webrev.00/
>
> We use trap instructions if UseSIGTRAP is enabled (PPC64 specific -XX flag) and fall back to loads from the polling pages otherwise.
>
> Please review.
>
> I will also need a sponsor because I’m changing the shared file safepointMechanism.cpp. It’s not a functional change for other platforms.
>
> Best regards,
>
> Martin
>
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