[heap] Add sqrt heap limit flag. [v8/v8 : main]

[Etienne Pierre-Doray (Gerrit)]

Attention needed from Dominik Inführ

Etienne Pierre-Doray voted and added 1 comment

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+1

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File src/flags/flag-definitions.h

Line 2699, Patchset 18: sqrt_allocation_limits, true,

Etienne Pierre-Doray . unresolved

TODO: disable

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[Dominik Inführ (Gerrit)]

Attention needed from Etienne Pierre-Doray

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File src/heap/heap-controller.cc

Line 265, Patchset 25 (Latest): computed_old_generation_allocation_limit = std::min<uint64_t>(

Dominik Inführ . unresolved

Can we have a SqrtLimit method here that we then reuse for old gen+global limit?

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[Dominik Inführ (Gerrit)]

Attention needed from Etienne Pierre-Doray

Dominik Inführ added 1 comment

File src/heap/heap-controller.cc

Line 263, Patchset 25 (Latest): // `total_size_excluding_external_at_last_gc_`, which includes young

Dominik Inführ . unresolved

Does `total_size_excluding_external_at_last_gc_` really need to be a field? I suppose we could also just compute `heap_->SizeOfObjects() + heap_->EmbedderSizeOfObjects()` here directly?

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[Etienne Pierre-Doray (Gerrit)]

Attention needed from Dominik Inführ

Etienne Pierre-Doray added 3 comments

Patchset-level comments

File-level comment, Patchset 26 (Latest):

Etienne Pierre-Doray . resolved

PTAnL?

File src/heap/heap-controller.cc

Line 263, Patchset 25: // `total_size_excluding_external_at_last_gc_`, which includes young

Dominik Inführ . unresolved

Does `total_size_excluding_external_at_last_gc_` really need to be a field? I suppose we could also just compute `heap_->SizeOfObjects() + heap_->EmbedderSizeOfObjects()` here directly?

Etienne Pierre-Doray

`heap_->SizeOfObjects() + heap_->EmbedderSizeOfObjects()` is different because it doesn't take a snapshot right after a GC, and since we can call UpdateAllocationLimits() in a few situations that's not right after a GC, this would give a different limit.

Line 265, Patchset 25: computed_old_generation_allocation_limit = std::min<uint64_t>(

Dominik Inführ . resolved

Can we have a SqrtLimit method here that we then reuse for old gen+global limit?

Etienne Pierre-Doray

Good idea, done!
I added a method to MemoryController, to reflect GrowingFactor.

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[Dominik Inführ (Gerrit)]

Attention needed from Etienne Pierre-Doray

Dominik Inführ voted and added 2 comments

Votes added by Dominik Inführ

Code-Review

+1

2 comments

Patchset-level comments

File-level comment, Patchset 26 (Latest):

Dominik Inführ . resolved

Thanks, LGTM

File src/heap/heap-controller.cc

Line 263, Patchset 25: // `total_size_excluding_external_at_last_gc_`, which includes young

Dominik Inführ . resolved

Does `total_size_excluding_external_at_last_gc_` really need to be a field? I suppose we could also just compute `heap_->SizeOfObjects() + heap_->EmbedderSizeOfObjects()` here directly?

Etienne Pierre-Doray

`heap_->SizeOfObjects() + heap_->EmbedderSizeOfObjects()` is different because it doesn't take a snapshot right after a GC, and since we can call UpdateAllocationLimits() in a few situations that's not right after a GC, this would give a different limit.

Dominik Inführ

Acknowledged

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[Etienne Pierre-Doray (Gerrit)]

Etienne Pierre-Doray added 2 comments

Patchset-level comments

File-level comment, Patchset 27 (Latest):

Etienne Pierre-Doray . resolved

Thanks!

File src/flags/flag-definitions.h

Line 2699, Patchset 18: sqrt_allocation_limits, true,

Etienne Pierre-Doray . resolved

TODO: disable

Etienne Pierre-Doray

Done

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[Etienne Pierre-Doray (Gerrit)]

Etienne Pierre-Doray voted Commit-Queue+2

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+2

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[v8-scoped@luci-project-accounts.iam.gserviceaccount.com (Gerrit)]

v8-s...@luci-project-accounts.iam.gserviceaccount.com submitted the change with unreviewed changes

Unreviewed changes

26 is the latest approved patch-set.
The change was submitted with unreviewed changes in the following files:

```
The name of the file: src/flags/flag-definitions.h
Insertions: 1, Deletions: 1.

@@ -2699,7 +2699,7 @@
            "Max external memory value (in GB) checked for a reasonable size, 0 "
            "to disable the check.")
 DEFINE_BOOL(
-    sqrt_allocation_limits, true,
+    sqrt_allocation_limits, false,
     "Old generation and global heap limit growth scale based on the sqrt of "
     "estimated GC cost.")
 DEFINE_INT(
```

Change information

Commit message:

[heap] Add sqrt heap limit flag.

This is a simple Sqrt heap limit implementation inspired from
https://arxiv.org/abs/2204.10455.
This is implemented behind sqrt_allocation_limits flag,
with a configurable growing factor limit.

Bug: 477484620

Change-Id: I52297256f62e30abda6d80e36b165684cf0f74e6

Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/7575773

Commit-Queue: Etienne Pierre-Doray <etie...@chromium.org>

Reviewed-by: Dominik Inführ <dinf...@chromium.org>

Cr-Commit-Position: refs/heads/main@{#107427}

Files:

• M src/flags/flag-definitions.h
• M src/heap/heap-controller.cc
• M src/heap/heap-controller.h

Change size: M

Delta: 3 files changed, 85 insertions(+), 17 deletions(-)

Branch: refs/heads/main

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