[GPU] Use array for tracking memory usage instead of map #25269
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`std::map` has very slow access are requires lock on every access. We can use `std::array` instead to hold compile time known number of buckets. This method should have less latency and memory overhead, as well as possibly no lock on access.
No need to lock mutex to update atomic values
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build_jenkins |
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Hi @ialbrecht, |
We had benchmarks were memory allocation was on the critical performance path and we were looking at all possible ways to optimize it. |
Make sure atomic values are zero initialized.
vladimir-paramuzov
changed the title
vladimir-paramuzov
approved these changes
Jul 3, 2024
| _peak_memory_usage_map[type] = _memory_usage_map[type].load(); | ||
| auto idx = static_cast<size_t>(type); | ||
| _memory_usage_data[idx] += bytes; | ||
| auto new_val = _memory_usage_data[idx].fetch_add(bytes); |
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Looks like the part above has a mistake - you count bytes twice (+= and fetch_add).
So I think here you need to replace fetch_add with load()
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Good catch. Still trying to get used to git and revieing my own diffs...
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fetch_add returns value before sum. I think it should be either:
auto new_val = _memory_usage_data[idx].fetch_add(bytes) + bytes;
or
_memory_usage_data[idx] += bytes;
auto new_val = _memory_usage_data[idx].load();
As in description
`fetch_add` returns old value, therefore we need to increment current memory usage value before storing current max.
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Details:
std::maphas very slow access are requires lock on every access. We can usestd::arrayinstead to hold compile time known number of buckets.arraycontainer has lower access latency and memory overhead.