Improve performance of allocation profiling #287
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- Adjust the pseudo random generator to be thread local - Change the generator to be smaller - Remove the lock from the allocation profiling path
| @@ -194,6 +190,10 @@ void AllocationTracker::track_allocation(uintptr_t addr, size_t size, | |||
| free_on_consecutive_failures(success); | |||
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| if (success && _state.track_deallocations) { | |||
| // \fixme{r1viollet} adjust set to be lock free | |||
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this could probably be replaced with a rather simple sparse bitset over the least significant 48 bits of the pointers, which would allow CAS operations on pages of the bitset rather than a lock.
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I like this, especially as the impact of collisions are easy to manage. I'll probably make it smaller than that.
| @@ -39,7 +44,7 @@ void perform_memory_operations(bool track_allocations, | |||
| std::mt19937 gen(rd()); | |||
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| for (auto _ : state) { | |||
| state.PauseTiming(); | |||
| // state.PauseTiming(); | |||
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why does this need to be commented out?
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Initially I was measuring the cost of deallocation. In this PR I was optimizing the allocation code path.
I think the correct thing to do is have different benchmarks. I am continuing this work and I'll revisit this.
sanchda
approved these changes
Jul 25, 2023
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What does this PR do?
Credit for this idea goes to @nsavoire
Motivation
Improve performance of allocation profiling. This really brings down the allocation profiling to numbers that are comparable.
The numbers were 4x worse prior to this change.
After this change I will need to focus on the deallocation code path.
Additional Notes
This needs extensive testing.
Risks are:
How to test the change?
The benchmark only tests parts of this. We will need to be careful when deploying this change.