8291945: Add OSInfo API for static OS information by iklam · Pull Request #9758 · openjdk/jdk

iklam · 2022-08-04T23:18:35Z

As suggested by @tstuefe in the review of #9600, many of the os APIs simply return a value that was initialized during VM start up. E.g., os::vm_page_size(). I have added a new class OSInfo for managing such info

Simplifies the per-OS implementation
Make the "init-only-once" check consistent
In some cases, the simpler OSInfo class can be used in lieu of the more complex os class. This improves HotSpot build time (e.g., relocInfo.hpp).

Note: I moved only 2 fields in this PR as a first step. If this works well I plan to move more fields in the future.

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JDK-8291945: Add OSInfo API for static OS information

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David Holmes (@dholmes-ora - Reviewer) ⚠️ Review applies to 9e918e8e
Thomas Stuefe (@tstuefe - Reviewer) ⚠️ Review applies to 3da77fcb

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bridgekeeper · 2022-08-04T23:20:27Z

👋 Welcome back iklam! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2022-08-04T23:23:13Z

@iklam The following label will be automatically applied to this pull request:

hotspot

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

mlbridge · 2022-08-05T03:44:42Z

Webrevs

dholmes-ora

Seems reasonable, but I initially expected to see the os:: API removed and replaced by the OSInfo:: API, rather than OSInfo just being an internal implementation detail.

dholmes-ora · 2022-08-05T04:12:16Z

src/hotspot/share/runtime/osInfo.hpp

+#include "memory/allStatic.hpp"
+#include "utilities/debug.hpp"
+
+// Static information about the operation system. Initialized exactly once


s/operation/operating

dholmes-ora · 2022-08-05T04:13:12Z

src/hotspot/share/runtime/stackValue.hpp

 #include "runtime/handles.hpp"

 class BasicLock;
+class frame;


Seems unrelated to this change. ?/

This file was indirectly including frame.hpp via os.hpp. Since I removed os.hpp from this file, I needed to add a declaration for the frame class.

I don't see any such removal in this file. ??

Oh I was mistaken. What I did was removing os.hpp from relocInfo.hpp and safepointMechanismhpp. This exposed the fact that stackValue.hpp was using the frame class without a proper declaration.

iklam · 2022-08-05T04:59:41Z

Seems reasonable, but I initially expected to see the os:: API removed and replaced by the OSInfo:: API, rather than OSInfo just being an internal implementation detail.

I left os::vm_page_size() because:

It's used by a lot of places. I don't want this PR to be overwhelmed by such changes.
os::vm_page_size() is often used together with other os::xxx functions related to memory allocation.

So at this point, OSInfo is a just lower-level API if you just want to find out the value of some OS parameters. So far I've used it in two popular headers to avoid including os.hpp

dholmes-ora · 2022-08-05T05:05:50Z

Okay I think it would be good to switch to the OSInfo API in the future, so that we reduce the scope of os even further and more clearly delineate an API to request services from the OS, and a simple query API for the OS.

openjdk · 2022-08-05T05:08:26Z

@iklam This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8291945: Add OSInfo API for static OS information

Reviewed-by: dholmes, stuefe

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been no new commits pushed to the master branch. If another commit should be pushed before you perform the /integrate command, your PR will be automatically rebased. If you prefer to avoid any potential automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

tstuefe

Looks good!

Cheers, Thomas

tstuefe · 2022-08-05T12:17:28Z

src/hotspot/share/runtime/osInfo.hpp

+  // Returns the byte size of a virtual memory page
+  static int vm_page_size() { return _vm_page_size; }
+
+  // Returns the size in bytes of memory blocks which can be allocated.


Too vague and a bit misleading. Proposal:

Returns size, in bytes, of the granularity with which memory can be reserved using os::reserve_memory().

…add-OSInfo-api

iklam · 2022-08-11T23:02:33Z

Thanks @dholmes-ora and @tstuefe for the review.
/integrate

openjdk · 2022-08-11T23:15:03Z

Going to push as commit 9bfffa0.

openjdk · 2022-08-11T23:16:10Z

@iklam Pushed as commit 9bfffa0.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

8291945: Add OSInfo API for static OS information

5a1e0cb

openjdk bot added the hotspot hotspot-dev@openjdk.org label Aug 4, 2022

fixed zero build; added comments

9e918e8

iklam marked this pull request as ready for review August 5, 2022 03:38

openjdk bot added the rfr Pull request is ready for review label Aug 5, 2022

dholmes-ora reviewed Aug 5, 2022

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dholmes-ora approved these changes Aug 5, 2022

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openjdk bot added the ready Pull request is ready to be integrated label Aug 5, 2022

fixed typo

3da77fc

tstuefe approved these changes Aug 11, 2022

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iklam added 2 commits August 11, 2022 14:52

@tstuefe review -- clarify comments

e86253b

Merge branch 'master' of https://github.com/openjdk/jdk into 8291945-…

faa28f6

…add-OSInfo-api

openjdk bot added the integrated Pull request has been integrated label Aug 11, 2022

openjdk bot closed this Aug 11, 2022

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Aug 11, 2022

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