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base repository: NixOS/nix
base: 169e1478d88b
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head repository: NixOS/nix
compare: 0629601da1d1
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  • 6 commits
  • 9 files changed
  • 1 contributor

Commits on Jun 12, 2018

  1. Remove duplicate definition of allocBytes()

    @edolstra
    edolstra committed Jun 12, 2018
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  2. Cache parse trees 

    This prevents EvalState::resetFileCache() from parsing everything all
over again.
    @edolstra
    edolstra committed Jun 12, 2018
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  3. Add temporary stats

    @edolstra
    edolstra committed Jun 12, 2018
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  4. Don't scan for roots in dynamic libraries 

    This reduces the risk of object liveness misdetection. For example,
Glibc has an internal variable "mp_" that often points to a Boehm
object, keeping it alive unnecessarily. Since we don't store any
actual roots in global variables, we can just disable data segment
scanning.

With this, the max RSS doing 100 evaluations of
nixos.tests.firefox.x86_64-linux.drvPath went from 718 MiB to 455 MiB.
    @edolstra
    edolstra committed Jun 12, 2018
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  5. GC_malloc -> GC_MALLOC 

    This makes it possible to build with -DGC_DEBUG.
    @edolstra
    edolstra committed Jun 12, 2018
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  6. Move EvalState from the stack to the heap 

    EvalState contains a few counters (e.g. nrValues) that increase
quickly enough that they end up being interpreted as pointers by the
garbage collector. Moving it to the heap makes them invisible to the
garbage collector.

This reduces the max RSS doing 100 evaluations of
nixos.tests.firefox.x86_64-linux.drvPath from 455 MiB to 292 MiB.

Note: ideally, allocations would be much further up in the 64-bit
address space to reduce the odds of an integer being misinterpreted as
a pointer. Maybe we can use some linker magic to move the .bss segment
to a higher address.
    @edolstra
    edolstra committed Jun 12, 2018
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