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fix: L3 max bandwidth buffer size for more accurate results #669

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fix: L3 max bandwidth buffer size for more accurate results #669

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14 changes: 12 additions & 2 deletions internal/script/scripts.go
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Original file line number Diff line number Diff line change
Expand Up @@ -176,9 +176,19 @@ BUF_KB=$(( L1D_KB / 2 - 4 ))
mlcBufferSetupL2 = `L2_KB=$(cache_size_kb L2)
BUF_KB=$(( L2_KB / 2 ))
[ $BUF_KB -lt 1 ] && BUF_KB=1`
// for measuring L3 bandwidth and latency (4x of L2 cache size)
// for measuring L3 idle latency (4x of L2 cache size, single thread)
mlcBufferSetupL3 = `L2_KB=$(cache_size_kb L2)
BUF_KB=$(( L2_KB * 4 ))
[ $BUF_KB -lt 1 ] && BUF_KB=1`
// for measuring L3 max bandwidth (80% of per-thread L3 share, all threads)
mlcBufferSetupL3BW = `L2_KB=$(cache_size_kb L2)
L3_KB=$(cache_size_kb L3)
TPC=$(lscpu | grep 'Thread(s) per core' | awk '{print $NF}')
CPS=$(lscpu | grep -E 'Core\(s\) per socket:' | head -1 | awk '{print $4}')
TOTAL=$(( TPC * CPS ))
BUF_KB=$(( L3_KB * 8 / 10 / TOTAL ))
MIN_KB=$(( L2_KB / TPC + 1 ))
[ $BUF_KB -lt $MIN_KB ] && BUF_KB=$MIN_KB
[ $BUF_KB -lt 1 ] && BUF_KB=1`
)

Expand Down Expand Up @@ -1156,7 +1166,7 @@ echo $__DEFAULT_HL_DEVICE
},
L3MaxBandwidthBenchmarkScriptName: {
Name: L3MaxBandwidthBenchmarkScriptName,
ScriptTemplate: mlcBenchmarkScript(mlcBufferSetupL3, "--loaded_latency -d0 -T -b${BUF_KB} -t10 -u"),
ScriptTemplate: mlcBenchmarkScript(mlcBufferSetupL3BW, "--loaded_latency -d0 -T -b${BUF_KB} -t10"),
Superuser: true,
Lkms: []string{"msr"},
Depends: []string{"mlc"},
Expand Down
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