Hi Lin,
On 31/03/2020 12:39 pm, linzang(臧琳) wrote:
Hi David, Henry, Alan,
Thanks a lot for your review.
I have considered use clock_gettime() first, but I seached the code and
found there is a marco SUPPORTS_CLOCK_MONOTONIC guard the usage of it. Which
makes me think it may not be available under specific situation. So I choosed
gettimeofday.
Do you think the patch need to be refined to remove HAVE_GETHRTIME as Alan
suggested? Thanks.
Leaving it as-is seems okay. Though the likelihood of anyone taking
advantage of an existing gethrtime() function anywhere other than
Solaris seems near zero. But if the Solaris port deprecation goes ahead
the point will be moot as only the "linux" version will remain.
This comment block needs fixing up:
37 /*
38 * * Add gethrtime() implementation for launch time debug on Linux.
39 * */
Also a nit but the new function can be called whatever you like as you
are defining CounterGet, so calling it gethrtime() is a bit misleading -
I suggest getTimeMicros().
Thanks,
David
BRs,
Lin
>On 2020/3/31, 8:05 AM, "David Holmes" <david.hol...@oracle.com> wrote:
On 31/03/2020 4:08 am, Henry Jen wrote:
> Based on my understanding to gethrtime(), the main benefit is not to be
affected by settimeofday or adjtime. I think it is probably better to use
>
> clock_gettime(CLOCK_MONOTONIC_RAW, ts);
>
> which I checked seems to be available on both Linux and Mac. Haven’t test
it though.
Not guaranteed to be available - either clock_gettime function or that
particular clock - at build time or runtime. We use a check in the build
system to determine build-time availability for hotspot, and then use
dl_lookup etc at runtime to determine if actually available. We should
be able to get rid of this one day but we checked fairly recently and
there were still some issues.
gettimeofday is a lot better than returning 1. Otherwise call into the
VM and use JVM_NanoTime.
Cheers,
David
-----
> Cheers,
> Henry
>
>> On Mar 30, 2020, at 1:37 AM, Alan Bateman <alan.bate...@oracle.com>
wrote:
>>
>> On 30/03/2020 03:41, linzang(臧琳) wrote:
>>> Dear All,
>>> May I ask your help to reivew this tiny patch? Thanks.
>>>
>>>
>>>
>>> BRs,
>>> Lin
>>>
>>> From: "linzang(臧琳)" <linz...@tencent.com>
>>> Date: Thursday, March 26, 2020 at 3:13 PM
>>> To: "core-libs-dev@openjdk.java.net" <core-libs-dev@openjdk.java.net>
>>> Subject: RFR(S): 8241638: launcher time metrics alway report 1 on Linux
when _JAVA_LAUNCHER_DEBUG set
>>>
>>> Dear All,
>>> May I ask your help to review this tiny fix?
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8241638
>>> Webrev: http://cr.openjdk.java.net/~lzang/8241638/webrev01/
>>> Thanks!
>>>
>> Using gettimeofday on non-Solaris platforms seems reasonable here. The
comment in the patch suggests Linux but it's other Unix builds too. Also just a minor
nit that the code in java.base uses 4-space indent, not 2. Looking at the patch makes me
wondering if we should remove HAVE_GETHRTIME as it seems to be only used on Solaris
>and the launcher is already using #ifdef __solaris__ in several places. Henry, do
you have any comments on this?
> >>
> >> -Alan
> >
