RFR: JDK-8256155: os::Linux Populate all large_page_sizes, select smallest page size in reserve_memory_special_huge_tlbfs* [v16]

Sat Mar 13 06:56:10 UTC 2021

On Thu, 11 Mar 2021 22:32:35 GMT, Marcus G K Williams <github.com+168222+mgkwill at openjdk.org> wrote:

>>> Hi @kstefanj and @tstuefe . Trying to resolve your comments and working through your suggestions. I will be responding more over the next day or so as I try to implement and understand what you are proposing. Thanks again for your review and suggestions.
>> 
>> Well, thanks for your patience :)
>
> Hello @tstuefe & @kstefanj. 
> 
> I've updated the change to implement your suggestions, all of them hopefully. I'd appreciate any further review and suggestions.
> 
> There is one issue with the current code set for which I wanted to get suggestions. Invariably 
> `os::page_size_for_region_aligned(bytes, 1)` in `os::Linux::reserve_memory_special_huge_tlbfs_mixed` returns with 4096, which of course breaks the assert `assert(large_page_size > (size_t)os::vm_page_size(), "large page size: %ld not larger than small page size: %ld", large_page_size, (size_t)os::vm_page_size());` - Line 4059 in os_linux.cpp. 
> 
> Here is the ps.log:
> 
>> # A fatal error has been detected by the Java Runtime Environment:
>> #
>> #  Internal Error (/home/mgkwill/src/git/jdk/src/hotspot/os/linux/os_linux.cpp:4059), pid=2789288, tid=2789289
>> #  assert(large_page_size > (size_t)os::vm_page_size()) failed: large page size: 4096 not larger than small page size: 4096
>> #
>> # JRE version:  (17.0) (slowdebug build )
>> # Java VM: OpenJDK 64-Bit Server VM (slowdebug 17-internal+0-adhoc.mgkwill.jdk, mixed mode, sharing, tiered, compressed oops, compressed class ptrs, serial gc, linux-amd64)
>> # Problematic frame:
>> # V  [libjvm.so+0xfb660a]  os::Linux::reserve_memory_special_huge_tlbfs_mixed(unsigned long, unsigned long, char*, bool)+0x146
>> #
>> # Core dump will be written. Default location: Core dumps may be processed with "/usr/lib/systemd/systemd-coredump %P %u %g %s %t %c %h" (or dumping to /home/mgkwill/src/git/jdk/build/linux-x86_64-server-slowdebug/test-support/jtreg_test_hotspot_jtreg_runtime_os_TestTracePageSizes_java/scratch/1/core.2789288)
>> #
>> # An error report file with more information is saved as:
>> # /home/mgkwill/src/git/jdk/build/linux-x86_64-server-slowdebug/test-support/jtreg_test_hotspot_jtreg_runtime_os_TestTracePageSizes_java/scratch/1/hs_err_pid2789288.log
>> #
>> #
>> Aborted (core dumped)
>> ps-2789288.log:
>> [0.002s][info][pagesize] Available page sizes: 4k, 2M, 1G
>> [0.003s][info][pagesize] Available large page sizes: 2M, 1G
>> [0.005s][info][pagesize] Large page size returned from os::page_size_for_region_aligned: 2097152, for bytes: 251658240
>> [0.005s][info][pagesize] Page size returned from (size_t)os::vm_page_size(): 4096
>> [0.005s][info][pagesize] Memory: 4k page, physical 131844416k(13735672k free), swap 0k(0k free)
>> [0.005s][info][pagesize] 2048k default large page
>> [0.005s][info][pagesize] Page Sizes: 4k, 2M, 1G
>> [0.005s][info][pagesize] CodeHeap 'non-nmethods':  min=4M max=6M base=0x00007f8edc600000 page_size=2M size=6M
>> [0.006s][info][pagesize] CodeHeap 'profiled nmethods':  min=4M max=116M base=0x00007f8edcc00000 page_size=2M size=116M
>> [0.007s][info][pagesize] CodeHeap 'non-profiled nmethods':  min=4M max=118M base=0x00007f8ee4000000 page_size=2M size=118M
>> [0.023s][info][pagesize] Large page size returned from os::page_size_for_region_aligned: 2097152, for bytes: 16202596352
>> [0.023s][info][pagesize] Page size returned from (size_t)os::vm_page_size(): 4096
>> [0.023s][info][pagesize] Memory: 4k page, physical 131844416k(13735672k free), swap 0k(0k free)
>> [0.023s][info][pagesize] 2048k default large page
>> [0.023s][info][pagesize] Page Sizes: 4k, 2M, 1G
>> [0.023s][info][pagesize] Heap:  min=8M max=15452M base=0x000000043a400000 page_size=2M size=15452M
>> [0.023s][info][pagesize] Card Table:  min=31645697B max=31645697B base=0x00007f8ef8919000 page_size=4K size=30908K
>> [0.825s][info][pagesize] Large page size returned from os::page_size_for_region_aligned: 4096, for bytes: 21098496
>> [0.825s][info][pagesize] Page size returned from (size_t)os::vm_page_size(): 4096
>> [0.825s][info][pagesize] Memory: 4k page, physical 131844416k(13732388k free), swap 0k(0k free)
>> [0.825s][info][pagesize] 2048k default large page
>> [0.825s][info][pagesize] Page Sizes: 4k, 2M, 1G
> 
> I'm not sure I understand why `Large page size returned from os::page_size_for_region_aligned: 4096, for bytes: 21098496`. 
> 
> Any suggestions as to the issue and solution? Once I solve this I will remove the excessive logging.
> 
> FYI: The above issue is what is failing linux x86 and x64 testing:
> Test results: passed: 4; failed: 2                                                                                                                                                                                Report written to /home/mgkwill/src/git/jdk/build/linux-x86_64-server-slowdebug/test-results/jtreg_test_hotspot_jtreg_runtime_os_TestTracePageSizes_java/html/report.html                                         Error: Some tests failed or other problems occurred.
> Results written to /home/mgkwill/src/git/jdk/build/linux-x86_64-server-slowdebug/test-support/jtreg_test_hotspot_jtreg_runtime_os_TestTracePageSizes_java
> Finished running test 'jtreg:test/hotspot/jtreg/runtime/os/TestTracePageSizes.java'
> Test report is stored in build/linux-x86_64-server-slowdebug/test-results/jtreg_test_hotspot_jtreg_runtime_os_TestTracePageSizes_java
> 
> ==============================
> Test summary
> ==============================
>    TEST                                              TOTAL  PASS  FAIL ERROR
>    jtreg:test/hotspot/jtreg/runtime/os/TestTracePageSizes.java
>>>                                                       6     4     2     0
> 
> Thanks,
> Marcus

Hi Markus, could you please edit your last comment and use three backticks:
long log output
Thanks!

-------------

PR: https://git.openjdk.java.net/jdk/pull/1153