[LibOS] Fix memmgr free list performance bug

[adrianlut]

[LibOS] Fix memmgr free list performance bug

Fixes the memmgr performance bug described in #2033 by changing the CHECK_LIST_HEAD macro in common/include/list.h in release mode to (void)0.

Description of the changes

To fix the issue described in #2033, this PR surrounds the CHECK_LIST_HEAD macro defined in
common/include/list.h
with #ifdef DEBUG. In release mode, the macro is now replaced with (void)0.

This macro is currently only used in memmgr.h. Thus, changing it directly was the simplest fix of the performance bug.

Fixes #2033

How to test this PR?

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This change is 

[mkow]

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: all files reviewed, 2 unresolved discussions, not enough approvals from maintainers (3 more required), not enough approvals from different teams (2 more required, approved so far: ) (waiting on @adrianlut)

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-- commits line 4 at r1:
Please wrap (see https://commit.style/).

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-- commits line 4 at r1:
We don't reference GitHub issues in the commits, we try to keep the git repo standalone. One reason for that is that this will turn into a dangling pointer if we'd move the repository somewhere else.

Code quote:

#2033

[mkow]

Jenkins, test this please

[adrianlut]

Thank you for the review. I changed the commit message as requested.

Reviewable status: all files reviewed, 2 unresolved discussions, not enough approvals from maintainers (3 more required), not enough approvals from different teams (2 more required, approved so far: ) (waiting on @mkow)

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-- commits line 4 at r1:

Previously, mkow (Michał Kowalczyk) wrote…

Please wrap (see https://commit.style/).

Done.

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-- commits line 4 at r1:

Previously, mkow (Michał Kowalczyk) wrote…

We don't reference GitHub issues in the commits, we try to keep the git repo standalone. One reason for that is that this will turn into a dangling pointer if we'd move the repository somewhere else.

Done.

[mkow]

Reviewed all commit messages.
Reviewable status: all files reviewed, all discussions resolved, not enough approvals from maintainers (2 more required), not enough approvals from different teams (1 more required, approved so far: ITL)

[mkow]

Jenkins, retest this please

[kailun-qin]

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion, not enough approvals from maintainers (1 more required) (waiting on @adrianlut)

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-- commits line 5 at r2:
Can be fixed during rebase -- I suggest to briefly mention the issue and add more back quotes, e.g., sth like:

The `CHECK_LIST_HEAD` macro in `common/include/list.h` is used in memmgr
to traverse the free list and perform assertion checks. However, the
loop is not removed by the compiler even in release mode, leading to
unnecessary overhead. This commit fixes this by changing the macro to
`(void)0` in release mode.

Code quote:

  Fixes a memmgr performance bug by changing the CHECK_LIST_HEAD macro in
  common/include/list.h in release mode to `(void)0`.

[mkow]

Reviewed all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved

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-- commits line 5 at r2:

Previously, kailun-qin (Kailun Qin) wrote…

Can be fixed during rebase -- I suggest to briefly mention the issue and add more back quotes, e.g., sth like:

The `CHECK_LIST_HEAD` macro in `common/include/list.h` is used in memmgr
to traverse the free list and perform assertion checks. However, the
loop is not removed by the compiler even in release mode, leading to
unnecessary overhead. This commit fixes this by changing the macro to
`(void)0` in release mode.

Done.

[mkow]

Jenkins, retest this please

[kailun-qin]

Reviewed all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved

[mkow]

Jenkins, retest this please (a lot of connectivity errors on Jenkins, e.g. Caused: hudson.remoting.ChannelClosedException: Channel "hudson.remoting.Channel@258ebcb3:penguins-3-noble": Remote call on penguins-3-noble failed. The channel is closing down or has closed down)

[mkow]

Jenkins, retest Jenkins-Direct-24.04 please (connectivity issues in CI again)

[mkow]

Jenkins, retest Jenkins-SGX-24.04-musl please (connectivity issues in CI again)