RFR: 8263464: NMT: assert in gtest os.release_multi_mappings_vm [v2]

[Gerard Ziemski]

On Mon, 8 May 2023 06:10:02 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> Gerard Ziemski has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   support partial release, add corresponding test
>
> test/hotspot/gtest/runtime/test_os.cpp line 553:
> 
>> 551: }
>> 552: #endif // !AIX
>> 553: 
> 
> - This tests case B, and we need case C and D too.
> - You should make the first - middle - release the testing release with the partwise releasing. The final release is just to clean up the mess. For that to work, the stripes must be larger and a multiple of os::allocation_granularity, since otherwise you cannot release them partwise.
> 
> Would be cool if you fit all of these cases into a single function, e.g. 
> 
> static void test_multi_release(size_t stripe_size, int num_stripes, size_t release_range_offset, size_t release_range_size)
> 
> 
> And then call them 4 times in 4 tests, for each of the test cases. E.g. with a stripe len set to 1M could be like this:
> 
> 
> TEST_VM(TEST_VM, release_multi_mappings_full_regions) {
>   test_multi_release(M, 4, M, 2*M); // release stripes 2 and 3 fully
> }
> 
> TEST_VM(TEST_VM, release_multi_mappings_partial_regions) {
>   test_multi_release(M, 4, M + 512*K, 512*K + M); // release stripe 2 partly, stripe 3 fully
> }
> 
> TEST_VM(TEST_VM, release_multi_mappings_partial_regions) {
>   test_multi_release(M, 4, M, M + 512*K); // release stripe 2 fully, stripe 3 partly
> }
> 
> TEST_VM(TEST_VM, release_multi_mappings_partial_regions) {
>   test_multi_release(M, 4, M + 256K, 512 * K); // release a 512K hole into stripe 2
> }

I tried to make a picture of the memory and the parts that should get released for testing:


//  allocate              [aaaa][bbbb][cccc][dddd]

//  1 release partial     [....][bbbb][....][....]
//  2 release partial     [....][....][cccc][....]
//  3 release partial     [....][bbbb][cccc][....]
//  4 release partial     [....][..bb][cccc][....]
//  5 release partial     [....][bb..][cccc][....]
//  6 release partial     [....][bbbb][cc..][....]
//  7 release partial     [....][bbbb][..cc][....]
//  8 release partial     [....][..bb][cc..][....]
//  9 release partial     [....][bb..][..cc][....]
// 10 release partial     [....][bb..][cc..][....]
// 11 release partial     [....][..bb][..cc][....]
// 12 release partial     [....][.bb.][....][....]
// 13 release partial     [....][.bb.][.cc.][....]


Are we still missing any cases?

Did I add too much? (i.e. drop case 13?)

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PR Review Comment: https://git.openjdk.org/jdk/pull/13813#discussion_r1187657600