Binary request generator/replayer #307
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Apr 30, 2024
cachelib/cachebench/util/Config.h
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| uint32_t ampFactor{1}; | ||
| uint32_t ampSizeFactor{1}; |
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what is the difference between ampFactor and ampSizeFactor?
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added comment - ampSizeFactor is ampFactor for item size
| op = o; | ||
| ttlSecs = ttl; | ||
| requestId = reqId; | ||
| sizeBegin = std::vector<size_t>::iterator(valueSize); |
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same here. what about sizeEnd?
| uint64_t lines_ = 0; | ||
| }; | ||
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| class BinaryFileStream { |
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Move to a separate file
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I think this fits really well under the trace file stream class, should both of those go to a new file?
------------------------ This offers much lower overhead of trace replaying. It assumes the kvcache trace format and kvcache behavoir. This patch supports the following: - binary request generation and replay - fast forwarding of a trace - preloading requests into memory - object size amplification - queue free for even lower request overhead - can parse many more requests per second than cachelib can process, so we can get 100% CPU usage The limitations are: - no trace amplification (however you can amplify the original .csv trace and save it in binary format) - ~4GB overhead per 100 million requests - you need some disk space to store large traces Example usage: /opt/cachelib/bin/binary_trace_gen --json_test_config opt/cachelib/test_configs/trace_replay/kvcache/config_kvtrace_gen_binary.json --progress 1 /opt/cachelib/bin/cachebench --json_test_config opt/cachelib/test_configs/trace_replay/kvcache/config_kvtrace_replay_binary.json --progress 1
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This is the binary trace replayer/generator that we have been using to achieve max CPU utilization for the kvcache traces in cachebench. With this generator, we can achieve a throughput of over 20 million op/sec using kvcache workload in cachebench. As a comparison, using the CSV replay generator we see only ~1.6 million op/sec due to dynamic allocations and parsing overhead.
We avoid allocations by mmap'ing the request data into memory and using a Request pointer to point to the request data rather than allocating a new request wrapper for each request.
To generate a binary request file from an existing kvcache trace (using the "replay" generator).
traceFileNamesortraceFileNameoption. Specify other properties such as ampFactor too.binaryFileName: "mybinaryfile.binas a config optionTo run a binary request trace specify the following:
traceFileName: "mybinaryfile.bin"and set ampSizeFactor (if desired)In summary - this patch offers much lower overhead of trace replaying. It does assumes the kvcache trace format and kvcache replay generator behavior. Additional features:
The limitations are:
original .csv trace and save it in binary format)