From: Nick Gasson <nick.gasson@arm.com>
To: Ian Rogers <irogers@google.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
Jiri Olsa <jolsa@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Stephane Eranian <eranian@google.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] perf jvmti: remove redundant jitdump line table entries
Date: Thu, 28 May 2020 12:38:56 +0800 [thread overview]
Message-ID: <xgl9y2pcfzbz.fsf@arm.com> (raw)
In-Reply-To: <CAP-5=fUXP7OVEAX+u7-t8VZ9d8xq747kWgdvC_s7=wiHg7iBSw@mail.gmail.com>
On 05/28/20 02:08 AM, Ian Rogers wrote:
>>
>> I noticed it loses information when the Hotspot code cache is
>> resized. I've been working around that by setting
>> -XX:InitialCodeCacheSize and -XX:ReservedCodeCacheSize to large
>> values. Does this help in your case?
>
> Thanks, I tried and also with Steve's patch:
> https://lore.kernel.org/lkml/1590544271-125795-1-git-send-email-steve.maclean@linux.microsoft.com/
Thanks for the reference! That patch fixes the problem I had with code
cache resizing so the workaround above is no longer necessary.
>
> Trying something very basic like just the -version command with compile only:
> /tmp/perf/perf record -k 1 -e cycles:u -F 6500 -o /tmp/perf.data java
> -agentpath:/tmp/perf/libperf-jvmti.so -XX:+PreserveFramePointer
> -XX:InitialCodeCacheSize=2G -XX:ReservedCodeCacheSize=2G
> -XX:CompileOnly=1 -version
> /tmp/perf/perf inject -i /tmp/perf.data -o /tmp/perf-jit.data -j
> /tmp/perf/perf report -i /tmp/perf-jit.data
>
> I don't see any of the JDK classes but 35 unknown symbols out of 272.
> The JDK classes are stripped to some degree iirc, but we should be
> able to give a symbol name as we don't care about local variables and
> like.
>
I tried this with latest perf/core and JDK 11 but I don't see any
[unknown] from jitted-*.so. All the events are in "Interpreter": I think
the options you want are -Xcomp -Xbatch rather than -XX:CompileOnly=1?
The latter restricts compilation to the named method/package.
There was a bug where no jitdump debug info was written for classes
compiled without line tables. That was fixed by d3ea46da3 ("perf jvmti:
Fix jitdump for methods without debug info").
--
Nick
next prev parent reply other threads:[~2020-05-28 4:39 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-22 6:53 [PATCH] perf jvmti: remove redundant jitdump line table entries Nick Gasson
2020-05-26 11:55 ` Jiri Olsa
2020-05-27 5:29 ` Nick Gasson
2020-05-27 12:43 ` Arnaldo Carvalho de Melo
2020-05-27 5:03 ` Ian Rogers
2020-05-27 5:40 ` Nick Gasson
2020-05-27 18:08 ` Ian Rogers
2020-05-28 4:38 ` Nick Gasson [this message]
2020-05-28 7:29 ` Ian Rogers
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