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    Revert of [heap] Parallel newspace evacuation, semispace copy, and compaction... · 85ba94f2
    machenbach authored
    Revert of [heap] Parallel newspace evacuation, semispace copy, and compaction \o/ (patchset #16 id:620001 of https://codereview.chromium.org/1577853007/ )
    
    Reason for revert:
    [Sheriff] Leads to crashes on all webrtc chromium testers, e.g.:
    https://build.chromium.org/p/chromium.webrtc/builders/Mac%20Tester/builds/49664
    
    Original issue's description:
    > [heap] Parallel newspace evacuation, semispace copy, and compaction \o/
    >
    > All parallelism can be turned off using --predictable, or --noparallel-compaction.
    >
    > This patch completely parallelizes
    >  - semispace copy: from space -> to space (within newspace)
    >  - newspace evacuation: newspace -> oldspace
    >  - oldspace compaction: oldspace -> oldspace
    >
    > Previously newspace has been handled sequentially (semispace copy, newspace
    > evacuation) before compacting oldspace in parallel. However, on a high level
    > there are no dependencies between those two actions, hence we parallelize them
    > altogether. We base the number of evacuation tasks on the overall set of
    > to-be-processed pages (newspace + oldspace compaction pages).
    >
    > Some low-level details:
    >  - The hard cap on number of tasks has been lifted
    >  - We cache store buffer entries locally before merging them back into the global
    >    StoreBuffer in a finalization phase.
    >  - We cache AllocationSite operations locally before merging them back into the
    >    global pretenuring storage in a finalization phase.
    >  - AllocationSite might be compacted while they would be needed for newspace
    >    evacuation. To mitigate any problems we defer checking allocation sites for
    >    newspace till merging locally buffered data.
    >
    > CQ_EXTRA_TRYBOTS=tryserver.v8:v8_linux_arm64_gc_stress_dbg,v8_linux_gc_stress_dbg,v8_mac_gc_stress_dbg,v8_linux64_asan_rel,v8_linux64_tsan_rel,v8_mac64_asan_rel
    > BUG=chromium:524425
    > LOG=N
    > R=hpayer@chromium.org, ulan@chromium.org
    >
    > Committed: https://crrev.com/8f0fd8c0370ae8c5aab56491b879d7e30c329062
    > Cr-Commit-Position: refs/heads/master@{#33523}
    
    TBR=hpayer@chromium.org,ulan@chromium.org,mlippautz@chromium.org
    # Skipping CQ checks because original CL landed less than 1 days ago.
    NOPRESUBMIT=true
    NOTREECHECKS=true
    NOTRY=true
    BUG=chromium:524425
    
    Review URL: https://codereview.chromium.org/1643473002
    
    Cr-Commit-Position: refs/heads/master@{#33539}
    85ba94f2
BUILD.gn 58.5 KB