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From "Tim Armstrong (Code Review)" <>
Subject [Impala-ASF-CR] IMPALA-3203: Part 1: Free list implementation
Date Thu, 16 Mar 2017 21:29:59 GMT
Tim Armstrong has uploaded a new patch set (#3).

Change subject: IMPALA-3203: Part 1: Free list implementation

IMPALA-3203: Part 1: Free list implementation

We will have a single free list per size class. Free buffers
are stored in a heap, ordered by the memory address of the
buffer, to help reduce address space fragmentation.

A follow-up patch will use the free lists in BufferPool.

Added unit tests for sanity checks and verification of behaviour
that is trickier to check in integration or system tests.
The cost will be exercised more thoroughly via BufferPool
in Part 2.

Includes a benchmark that demonstrates the scalability of
the free lists under concurrency. When measuring pure throughput
of free list operations, having a free list per core is
significantly faster than a shared free list, or allocating
directly from TCMalloc. On 8 cores, if the memory allocated is
actually touched then for 64KB+ buffers, memory access is the
bottleneck rather than lock contention.

This suggests that having a free list per core is more than sufficient
(however, we will need to validate this with system concurrency
benchmarks once we switch to using this during query execution).

Change-Id: Ia89acfa4efdecb96d3678443b4748932b4133b9b
M be/src/benchmarks/CMakeLists.txt
A be/src/benchmarks/
M be/src/runtime/bufferpool/CMakeLists.txt
M be/src/runtime/bufferpool/
M be/src/runtime/bufferpool/buffer-allocator.h
M be/src/runtime/bufferpool/
M be/src/runtime/bufferpool/buffer-pool.h
A be/src/runtime/bufferpool/
A be/src/runtime/bufferpool/free-list.h
9 files changed, 713 insertions(+), 21 deletions(-)

  git pull ssh:// refs/changes/10/6410/3
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: Ia89acfa4efdecb96d3678443b4748932b4133b9b
Gerrit-PatchSet: 3
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Tim Armstrong <>

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