Pls review 6887571
Paul Hohensee
Paul.Hohensee at Sun.COM
Wed Oct 28 12:26:06 PDT 2009
Excellent. Thanks!
Y.S.Ramakrishna at Sun.COM wrote:
> See my previous email re treatment of CMS wrt the ergo heap sizing
> affected here. I am find, though, with that happening is a separate CR.
> So I am fine with this going in in the current state (i.e. Paul's
> latest webrev as of this writing (webrev.04)).
>
> thanks.
> -- ramki
>
> On 10/28/09 08:25, Jon Masamitsu wrote:
>> Comment should probably say "initial heap size" instead of "minimum
>> heap size".
>>
>> 1357 if (!FLAG_IS_DEFAULT(InitialHeapSize)) {
>> 1358 // A minimum heap size was specified on the command line,
>>
>>
>> Instead of this,
>>
>> 2719 // Set heap size based on available physical memory.
>> 2720 // CMS uses its own heap size ergo.
>> 2721 if (!UseConcMarkSweepGC) {
>> 2722 set_heap_size();
>> 2723 }
>> 2724
>> 2725 if (UseParallelGC || UseParallelOldGC) {
>> 2726 // Set some flags for ParallelGC if needed.
>> 2727 set_parallel_gc_flags();
>> 2728 } else if (UseConcMarkSweepGC) {
>> 2729 // Set some flags for CMS
>> 2730 set_cms_and_parnew_gc_flags();
>> 2731 } else if (UseParNewGC) {
>> 2732 // Set some flags for ParNew
>> 2733 set_parnew_gc_flags();
>> 2734 } else if (UseG1GC) {
>> 2735 // Set some flags for garbage-first, if needed.
>> 2736 set_g1_gc_flags();
>> 2737 }
>>
>> consider
>>
>> if (UseConcMarkSweepGC) {
>> // Set some flags for cms and ParNew. If both
>> // UseConcMarkSweepGC and UseParNewGC are set,
>> // this is the call that should be done.
>> set_cms_and_parnew_gc_flags();
>> } else {
>> set_heap_size();
>> if (UseParallelGC || UseParallelOldGC) {
>> // Set some flags for ParallelGC if needed.
>> set_parallel_gc_flags();
>> } else if (UseParNewGC) {
>> // Set some flags for ParNew
>> set_parnew_gc_flags();
>> } else if (UseG1GC) {
>> // Set some flags for garbage-first, if needed.
>> set_g1_gc_flags();
>> }
>> }
>>
>>
>> I'd suggest adding the newly obsoleted flags (e.g., DefaultMaxRAM)
>> to the obsolete_jvm_flags[] in arguments.cpp. For example
>>
>> { "DefaultMaxRAM)", JDK_Version::jdk_update(6,16),
>> JDK_Version::jdk(8) }
>>
>>
>> That's all.
>>
>>
>> On 10/27/09 16:01, Paul Hohensee wrote:
>>> .02 has the fix for line 1105.
>>>
>>> I'll change MaxErgoHeapSize to ErgoHeapSizeLimit, unless someone
>>> else has another opinion. I'm not proud. :)
>>>
>>> Thanks for the review, and for reviewing interim versions.
>>>
>>> Paul
>>>
>>> Jon Masamitsu wrote:
>>>> Paul,
>>>>
>>>> Just a couple of comments from the .01 version
>>>> of the webrev. I haven't started the .02 version
>>>> yet so may have more comments after I do.
>>>>
>>>> Jon
>>>>
>>>> arguments.cpp
>>>>
>>>> 1105 InitialHeapSize = min_new + OldSize;
>>>>
>>>> Use FLAG_SET_ERGO()
>>>>
>>>> FLAG_SET_ERGO(uintx, InitialHeapSize, min_new + OldSize);
>>>>
>>>> Sometimes in the setting of the GC policies we like to
>>>> know how the flag was set.
>>>>
>>>> I like ErgoHeapSizeLimit instead of
>>>> MaxErgoHeapSize but just my preference.
>>>>
>>>>
>>>>
>>>> On 10/27/09 09:26, Paul Hohensee wrote:
>>>>> 6887571: Increase default heap config sizes
>>>>>
>>>>> Webrev here
>>>>>
>>>>> http://cr.openjdk.java.net/~phh/6887571/webrev.01/
>>>>>
>>>>> Some background:
>>>>>
>>>>> The default client vm heap config since 2000 for sparc32 has been
>>>>> the equivalent of
>>>>>
>>>>> -Xmx64m -XX:OldSize=4m -XX:NewSize=2m -XX:NewRatio=8
>>>>> -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=15
>>>>>
>>>>> and for 32-bit x86
>>>>>
>>>>> -Xmx64m -XX:OldSize=4m -XX:NewSize=1m -XX:NewRatio=12
>>>>> -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=15
>>>>>
>>>>> OldSize and NewSize are the initial committed sizes of the old and
>>>>> young generations
>>>>> respectively. A minor gc is required to increase the committed
>>>>> size of the young gen,
>>>>> while a full gc is required to increase the committed size of the
>>>>> old gen.
>>>>>
>>>>> At the time, 64m was half of the 128m of memory typically
>>>>> available on high-end
>>>>> desktops, many client applications were satisfied with small heaps
>>>>> (hence the
>>>>> low -Xms value), and gc times were such that the young gen had to
>>>>> be small
>>>>> in order to minimize pause times.
>>>>>
>>>>> Since that time, low end desktops and laptops, as well as netbooks
>>>>> and smartbooks,
>>>>> typically come with 256m, client applications have become much
>>>>> more "server-like",
>>>>> and we've realized that a small young gen size increases the
>>>>> frequency of young gcs
>>>>> and the amount of transient data promoted to the old gen to levels
>>>>> that noticeably
>>>>> impact startup and steady-state performance, principally by
>>>>> provoking full gcs.
>>>>>
>>>>> This change extends server class heap sizing to the client with a
>>>>> few changes.
>>>>> Server heap sizing ergonomics should be unaffected.
>>>>>
>>>>> 1. NewRatio is set to 2 for all platforms to accomodate an
>>>>> increase in transient data size.
>>>>>
>>>>> 2. SurvivorRatio is set to 8 for all platforms. It was 8 for
>>>>> every platform except
>>>>> 64-bit x86 (where it was 6) in any case, so it isn't a big change.
>>>>>
>>>>> 3. MaxTenuringThreshold is left at 15 (the maximum).
>>>>>
>>>>> 4. I added MaxRAM, whose implemented definition matches the
>>>>> current comment for DefaultMaxRAM
>>>>> in globals.hpp. MaxRAM is the maximum physical memory size used
>>>>> to compute MaxHeapSize
>>>>> rather than the maximum possible value of MaxHeapSize set by
>>>>> ergonomics. I replaced
>>>>> DefaultMaxRAM with MaxErgoHeapSize for the latter purpose. I
>>>>> added support for a new
>>>>> argument type, uint64_t, and used it as the type of MaxRAM. uintx
>>>>> doesn't have the necessary
>>>>> range on 32-bit systems: a user might want to specify 4g for
>>>>> MaxRAM on a 32-bit system.
>>>>>
>>>>> 5. The other Default* switches have been stripped of the "Default"
>>>>> prefix, since to me their
>>>>> values are just as much "default" values as the values of any of
>>>>> other vm switch, and those don't
>>>>> have a "Default" prefix. I left DefaultMaxRAMFraction as a
>>>>> synonym for MaxRAMFraction for
>>>>> the moment because QA uses it. When they change to
>>>>> MaxRAMFraction, I intend to remove
>>>>> DefaultMaxRAMFraction.
>>>>>
>>>>> 6. In arguments.cpp, set_heap_size() replaces
>>>>> set_server_heap_size() and is used for everything
>>>>> except CMS. CMS has it's own, incompatible (I know: I tried it),
>>>>> heap sizing ergonomics.
>>>>>
>>>>> 7. The minimum committed size of the old gen (OldSize) remains at
>>>>> 4m and the minimum
>>>>> committed size of the young gen (NewSize) increases to 4m. Note
>>>>> that these are the minimum,
>>>>> not initial sizes. NewSize is made common to all platforms.
>>>>>
>>>>> 8. I added a switch InitialHeapSize that can be used to set the
>>>>> initial committed size of the heap.
>>>>> Absent specification by InitialHeapSize, the initial committed
>>>>> size is 1/64th of physical memory
>>>>> or OldSize + NewSize, whichever is larger.
>>>>>
>>>>> 9. I cleaned up some formatting, esp. in globals.hpp.
>>>>>
>>>>> 10. The default MaxHeapSize is raised from 64m to 96m. For
>>>>> systems with <= MaxHeapSize
>>>>> physical memory, the minimum heap size is 1/MinRAMFraction of
>>>>> physical memory. The
>>>>> default value of MinRAMFraction is 2. Thus, a 256m box gets a 96m
>>>>> heap, as does a 128m
>>>>> box, but a 96m box gets a 48m heap and a 64m box gets a 32m heap.
>>>>> The default values of
>>>>> MaxRAM and MaxRAMFraction bound the maximum heap size to 256m for
>>>>> the client vms,
>>>>> 1g for 32-bit server vms and 32g for 64-bit server vms. The
>>>>> values for the server vms are
>>>>> the same as before. I picked 256m for client because I wanted to
>>>>> bound resource utilization
>>>>> on client systems. Also, benchmarks runs showed no extra benefit
>>>>> from going to 512m heaps.
>>>>> 512m is the safe maximum for the serial collector.
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Paul
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>
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