229 lines
6.6 KiB
C++
229 lines
6.6 KiB
C++
/*
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DISKSPD
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Copyright(c) Microsoft Corporation
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All rights reserved.
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MIT License
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED *AS IS*, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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#include "IoBucketizer.h"
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#include <stdexcept>
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/*
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Calculating stddev using an online algorithm:
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avg = sum(1..n, a[n]) / n
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stddev = sqrt(sum(1..n, (a[n] - avg)^2) / n)
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= sqrt(sum(1..n, a[n]^2 - 2 * a[n] * avg + avg^2) / n)
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= sqrt((sum(1..n, a[n]^2) - 2 * avg * sum(1..n, a[n]) + n * avg^2) / n)
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= sqrt((sum(1..n, a[n]^2) - 2 * (sum(1..n, a[n]) / n) * sum(1..n, a[n]) + n * (sum(1..n], a[n]) / n)^2) / n)
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= sqrt((sum(1..n, a[n]^2) - (2 / n) * sum(1..n, a[n])^2 + (1 / n) * sum(1..n, a[n])^2) / n)
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= sqrt((sum(1..n, a[n]^2) - (1 / n) * sum(1..n, a[n])^2) / n)
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So if we track n, sum(a[n]) and sum(a[n]^2) we can calculate the stddev. This
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is used to calculate the stddev of the latencies below.
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*/
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const unsigned __int64 INVALID_BUCKET_DURATION = 0;
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IoBucketizer::IoBucketizer()
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: _bucketDuration(INVALID_BUCKET_DURATION),
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_validBuckets(0),
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_totalBuckets(0)
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{}
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void IoBucketizer::Initialize(unsigned __int64 bucketDuration, size_t validBuckets)
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{
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if (_bucketDuration != INVALID_BUCKET_DURATION)
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{
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throw std::runtime_error("IoBucketizer has already been initialized");
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}
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if (bucketDuration == INVALID_BUCKET_DURATION)
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{
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throw std::invalid_argument("Bucket duration must be a positive integer");
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}
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_bucketDuration = bucketDuration;
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_validBuckets = validBuckets;
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_vBuckets.resize(_validBuckets);
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}
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void IoBucketizer::Add(unsigned __int64 ioCompletionTime, double ioDuration)
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{
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if (_bucketDuration == INVALID_BUCKET_DURATION)
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{
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throw std::runtime_error("IoBucketizer has not been initialized");
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}
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size_t bucketNumber = static_cast<size_t>(ioCompletionTime / _bucketDuration);
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_totalBuckets = bucketNumber + 1;
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if (bucketNumber >= _validBuckets)
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{
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return;
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}
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_vBuckets[bucketNumber].lfSumDuration += ioDuration;
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_vBuckets[bucketNumber].lfSumSqrDuration += ioDuration * ioDuration;
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if (_vBuckets[bucketNumber].ulCount == 0 ||
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ioDuration < _vBuckets[bucketNumber].lfMinDuration)
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{
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_vBuckets[bucketNumber].lfMinDuration = ioDuration;
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}
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if (_vBuckets[bucketNumber].ulCount == 0 ||
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ioDuration > _vBuckets[bucketNumber].lfMaxDuration)
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{
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_vBuckets[bucketNumber].lfMaxDuration = ioDuration;
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}
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_vBuckets[bucketNumber].ulCount++;
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}
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size_t IoBucketizer::GetNumberOfValidBuckets() const
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{
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return (_totalBuckets > _validBuckets ? _validBuckets : _totalBuckets);
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}
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unsigned int IoBucketizer::GetIoBucketCount(size_t bucketNumber) const
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{
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if (bucketNumber < _validBuckets)
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{
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return _vBuckets[bucketNumber].ulCount;
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}
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return 0;
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}
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double IoBucketizer::GetIoBucketMinDurationUsec(size_t bucketNumber) const
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{
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if (bucketNumber < _validBuckets)
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{
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return _vBuckets[bucketNumber].lfMinDuration;
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}
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return 0;
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}
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double IoBucketizer::GetIoBucketMaxDurationUsec(size_t bucketNumber) const
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{
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if (bucketNumber < _validBuckets)
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{
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return _vBuckets[bucketNumber].lfMaxDuration;
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}
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return 0;
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}
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double IoBucketizer::GetIoBucketAvgDurationUsec(size_t bucketNumber) const
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{
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if (bucketNumber < _validBuckets && _vBuckets[bucketNumber].ulCount != 0)
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{
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return _vBuckets[bucketNumber].lfSumDuration / static_cast<double>(_vBuckets[bucketNumber].ulCount);
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}
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return 0;
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}
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double IoBucketizer::GetIoBucketDurationStdDevUsec(size_t bucketNumber) const
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{
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if (bucketNumber < _validBuckets && _vBuckets[bucketNumber].ulCount != 0)
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{
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double sum_of_squares = _vBuckets[bucketNumber].lfSumSqrDuration;
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double square_of_sum = _vBuckets[bucketNumber].lfSumDuration * _vBuckets[bucketNumber].lfSumDuration;
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double count = static_cast<double>(_vBuckets[bucketNumber].ulCount);
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double square_stddev = (sum_of_squares - (square_of_sum / count)) / count;
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return sqrt(square_stddev);
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}
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return 0;
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}
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double IoBucketizer::_GetMeanIOPS() const
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{
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size_t numBuckets = GetNumberOfValidBuckets();
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double sum = 0;
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for (size_t i = 0; i < numBuckets; i++)
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{
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sum += static_cast<double>(_vBuckets[i].ulCount) / numBuckets;
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}
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return sum;
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}
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double IoBucketizer::GetStandardDeviationIOPS() const
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{
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size_t numBuckets = GetNumberOfValidBuckets();
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if(numBuckets == 0)
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{
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return 0.0;
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}
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double mean = _GetMeanIOPS();
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double ssd = 0;
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for (size_t i = 0; i < numBuckets; i++)
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{
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double dev = static_cast<double>(_vBuckets[i].ulCount) - mean;
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double sqdev = dev*dev;
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ssd += sqdev;
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}
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return sqrt(ssd / numBuckets);
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}
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void IoBucketizer::Merge(const IoBucketizer& other)
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{
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if(other._vBuckets.size() > _vBuckets.size())
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{
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_vBuckets.resize(other._vBuckets.size());
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}
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for(size_t i = 0; i < other._vBuckets.size(); i++)
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{
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_vBuckets[i].ulCount += other._vBuckets[i].ulCount;
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_vBuckets[i].lfSumDuration += other._vBuckets[i].lfSumDuration;
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_vBuckets[i].lfSumSqrDuration += other._vBuckets[i].lfSumSqrDuration;
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if (i >= _validBuckets ||
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other._vBuckets[i].lfMinDuration < _vBuckets[i].lfMinDuration)
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{
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_vBuckets[i].lfMinDuration = other._vBuckets[i].lfMinDuration;
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}
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if (other._vBuckets[i].lfMaxDuration > _vBuckets[i].lfMaxDuration)
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{
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_vBuckets[i].lfMaxDuration = other._vBuckets[i].lfMaxDuration;
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}
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}
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if (other._validBuckets > _validBuckets)
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{
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_validBuckets = other._validBuckets;
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}
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if (other._totalBuckets > _totalBuckets)
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{
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_totalBuckets = other._totalBuckets;
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}
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}
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