ZOS Use Default Large Page Type Within Objectheap and Codecache #7585
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AlenBadel
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OpenJ9 Docs PR: eclipse-openj9/openj9-docs#412 |
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@fjeremic could you take a look? |
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I am not sure we should allow to omit What I don't like what is driving this change: in attempt to do "mapping" of correspondent -XX options instead of handle them properly (like obviously -XX option does not have pageable/nonpageable info so use pageable as default) the -Xlp part is attempted to be changed. I believe this is wrong approach. |
That's not the motivation anymore. This is purely to be symmetrical with other platforms. The options |
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This change looks in wrong place. Parser does context free check. This code uses context (pages available on OS).
Looks like it should be somewhere in j9vmem_find_valid_page_size()
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So directly implemented into
https://github.com/eclipse/omr/blob/8b719f55ba3d8b8051b40b6dc4b38a1caa9afe5e/port/zos390/omrvmem.c#L1331
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So directly implemented into
https://github.com/eclipse/omr/blob/8b719f55ba3d8b8051b40b6dc4b38a1caa9afe5e/port/zos390/omrvmem.c#L1331
I believe this is the question.
I think you should take a look. It supports OMRPORT_VMEM_PAGE_FLAG_NOT_USED so there is a mechanism to handle unspecified [non]pageable there. However it seems does it differently and favour FIXED in this case as a legacy support.
I believe we need a discussion between ZOS - involved specialists about this proposed behaviour change (including motivation)
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I believe we need a discussion between ZOS - involved specialists about this proposed behaviour change (including motivation)
@joransiu Has already expressed that 1M pagerable large pages are preferred. If we don't have any obvious drawbacks I don't see why this can't be default behaviour. I think it adds value that the the command line option can be symmetrical along all architectures.
It's obvious on the codecache side that we don't have a choice of using nonpageable in the first place and mandatory requiring an additional option doesn't make sense.
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I'll make this change once we're on the same page and I'll let others chime in.
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@joransiu Could you kindly chime in on this? |
Previously, an additional [non]pageable argument is required when specifying a large page size for both the objectheap and codecache. This isn't uniform with X, and P. There isn't really a reason for nonpageable to be an option within the codecache since it doesn't support nonpageable large pages. It's also desireable that pageable large pages be used within the objectheap if both pageable, and nonpageable are available. In this commit contains the following changes: 1) The Codecache will use pageable large pages by default. The logic for nonpageable large pages will not be removed, since support can be added at a later time. 2) The Objectheap will use pageable large pages of the specified size if both nonpageable and pageable pages are available. This functionality can be used by specifying the following options for codecache, and objectheap respectively. -Xlp:codecache:pagesize=<size> -Xlp:objectheao:pagesize=<size> Signed-off-by: AlenBadel <[email protected]>
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Can one of the admins verify this patch? |
Previously, an additional [non]pageable argument is required when specifying a large page size for both the objectheap and codecache.
This isn't uniform with X, and P. There isn't really a reason for nonpageable to be an option within the codecache since it doesn't support nonpageable large pages.
It's also desireable that pageable large pages be used within the objectheap if both pageable, and nonpageable are available.
In this commit contains the following changes:
This functionality can be used by specifying the following options for codecache, and objectheap respectively.
-Xlp:codecache:pagesize=
-Xlp:objectheao:pagesize=
Signed-off-by: AlenBadel [email protected]