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Nov 1, 2022
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cosmetic changes made after code review #1

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6960422
cosmetic changes made after code review
guptask Nov 1, 2022
c8cfdd3
fix merge conflict
guptask Nov 1, 2022
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249 changes: 136 additions & 113 deletions cachelib/allocator/DynamicFreeThresholdStrategy.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -14,150 +14,173 @@
* limitations under the License.
*/

//class-specific dynamic free (high) threshold strategy

// class-specific dynamic free (high) threshold strategy

#include "cachelib/allocator/DynamicFreeThresholdStrategy.h"
#include "cachelib/allocator/memory/MemoryPoolManager.h"
#include "cachelib/allocator/memory/MemoryAllocator.h"
#include "cachelib/allocator/Cache.h"
#include "cachelib/allocator/CacheStats.h"

#include <folly/logging/xlog.h>
#include <stdlib.h>

#include <cmath>
#include <fstream>
#include <cmath>
#include <random>
#include <stdlib.h>
#include <random>

#include "cachelib/allocator/Cache.h"
#include "cachelib/allocator/CacheStats.h"
#include "cachelib/allocator/memory/MemoryAllocator.h"
#include "cachelib/allocator/memory/MemoryPoolManager.h"
namespace facebook {
namespace cachelib {




DynamicFreeThresholdStrategy::DynamicFreeThresholdStrategy(double lowEvictionAcWatermark, double highEvictionAcWatermark, uint64_t maxEvictionBatch, uint64_t minEvictionBatch, double highEvictionDelt )
: lowEvictionAcWatermark(lowEvictionAcWatermark), highEvictionAcWatermark(highEvictionAcWatermark), maxEvictionBatch(maxEvictionBatch), minEvictionBatch(minEvictionBatch), highEvictionDelta(highEvictionDelt),
highEvictionAcWatermarks(CacheBase::kMaxTiers,
std::vector<std::vector<std::vector<double>>>(MemoryPoolManager::kMaxPools,
std::vector<std::vector<double>>(MemoryAllocator::kMaxClasses,
std::vector<double>(3, highEvictionAcWatermark)))), //initialize highEvictionAcWatermarks
/*acBenefits(CacheBase::kMaxTiers,
std::vector<std::vector<std::vector<double>>>(MemoryPoolManager::kMaxPools,
std::vector<std::vector<double>>(MemoryAllocator::kMaxClasses,
std::vector<double>(2, 0.0)))), //initialize acBenefits
*/
acLatencies(CacheBase::kMaxTiers,
std::vector<std::vector<std::vector<double>>>(MemoryPoolManager::kMaxPools,
std::vector<std::vector<double>>(MemoryAllocator::kMaxClasses,
std::vector<double>(2, 0.0)))),
acToFreeMemPercents(CacheBase::kMaxTiers,
std::vector<std::vector<std::vector<double>>>(MemoryPoolManager::kMaxPools,
std::vector<std::vector<double>>(MemoryAllocator::kMaxClasses,
std::vector<double>(2, 0.0)))) {} //initialize acToFreeMemPercents

std::vector<size_t> DynamicFreeThresholdStrategy::calculateBatchSizes
(const CacheBase& cache, std::vector<MemoryDescriptorType> acVec)
{

std::vector<size_t> batches{}; //contain number of items to evict for ac classes in the batch


DynamicFreeThresholdStrategy::DynamicFreeThresholdStrategy(
double lowEvictionAcWatermark,
double highEvictionAcWatermark,
uint64_t maxEvictionBatch,
uint64_t minEvictionBatch,
double highEvictionDelt)
: lowEvictionAcWatermark(lowEvictionAcWatermark),
highEvictionAcWatermark(highEvictionAcWatermark),
maxEvictionBatch(maxEvictionBatch),
minEvictionBatch(minEvictionBatch),
highEvictionDelta(highEvictionDelt),
highEvictionAcWatermarks(
CacheBase::kMaxTiers,
std::vector<std::vector<std::vector<double>>>(
MemoryPoolManager::kMaxPools,
std::vector<std::vector<double>>(
MemoryAllocator::kMaxClasses,
std::vector<double>(
3,
highEvictionAcWatermark)))), // initialize
// highEvictionAcWatermarks

acLatencies(
CacheBase::kMaxTiers,
std::vector<std::vector<std::vector<double>>>(
MemoryPoolManager::kMaxPools,
std::vector<std::vector<double>>(MemoryAllocator::kMaxClasses,
std::vector<double>(2, 0.0)))),
acToFreeMemPercents(
CacheBase::kMaxTiers,
std::vector<std::vector<std::vector<double>>>(
MemoryPoolManager::kMaxPools,
std::vector<std::vector<double>>(MemoryAllocator::kMaxClasses,
std::vector<double>(2, 0.0)))) {
} // initialize acToFreeMemPercents

std::vector<size_t> DynamicFreeThresholdStrategy::calculateBatchSizes(
const CacheBase& cache, std::vector<MemoryDescriptorType> acVec) {
std::vector<size_t> batches{}; // contain number of items to evict for ac
// classes in the batch

for (auto [tid, pid, cid] : acVec) {

auto stats = cache.getAllocationClassStats(tid, pid, cid); //ac class stats
auto acFree = stats.approxFreePercent; //amount of free memory in the ac class

if (acFree >= lowEvictionAcWatermark) { //if the amount of free memory in the ac class is above lowEvictionAcWatermark,
batches.push_back(0); //we do not evict
auto stats = cache.getAllocationClassStats(tid, pid, cid); // ac class stats
auto acFree =
stats.approxFreePercent; // amount of free memory in the ac class

if (acFree >= lowEvictionAcWatermark) { // if the amount of free memory in
// the ac class is above
// lowEvictionAcWatermark,
batches.push_back(0); // we do not evict
} else {
auto acHighThresholdAtI = highEvictionAcWatermarks[tid][pid][cid][0]; //current high threshold
auto acHighThresholdAtINew = highEvictionAcWatermarks[tid][pid][cid][0]; //new high threshold, will be adjusted
auto acHighThresholdAtIMinus1 = highEvictionAcWatermarks[tid][pid][cid][1]; //previous high threshold
auto acHighThresholdAtIMinus2 = highEvictionAcWatermarks[tid][pid][cid][2]; //previous of previous high threshold
auto acHighThresholdAtI =
highEvictionAcWatermarks[tid][pid][cid][0]; // current high threshold
auto acHighThresholdAtINew =
highEvictionAcWatermarks[tid][pid][cid][0]; // new high threshold,
// will be adjusted
auto acHighThresholdAtIMinus1 =
highEvictionAcWatermarks[tid][pid][cid][1]; // previous high threshold
auto acHighThresholdAtIMinus2 =
highEvictionAcWatermarks[tid][pid][cid][2]; // previous of previous
// high threshold
auto toFreeMemPercentAtI = acToFreeMemPercents[tid][pid][cid][0];
auto toFreeMemPercentAtIMinus1 = acToFreeMemPercents[tid][pid][cid][1]; //previous amount of memory to free up in the ac class
auto acAllocLatencyNs = cache.getAllocationClassStats(tid, pid, cid).allocLatencyNs.estimate(); //moving avg latency estimation for ac class

auto toFreeMemPercentAtIMinus1 =
acToFreeMemPercents[tid][pid][cid][1]; // previous amount of memory to
// free up in the ac class
auto acAllocLatencyNs =
cache.getAllocationClassStats(tid, pid, cid)
.allocLatencyNs.estimate(); // moving avg latency estimation for
// ac class

calculateLatency(acAllocLatencyNs, tid, pid, cid);


std::default_random_engine generator;
std::normal_distribution<double> distribution(1);
double number=distribution(generator);
acHighThresholdAtINew+= number*highEvictionDelta;
std::normal_distribution<double> randDistribution(0.0,1.0);
double randoNum=randDistribution(generator);

if (acLatencies[tid][pid][cid][0] < acLatencies[tid][pid][cid][1]){ //if current latency reduced
// then increase threshold to increase eviction
//acHighThresholdAtINew+= number*highEvictionDelta;
highEvictionAcWatermarks[tid][pid][cid][0]=acHighThresholdAtINew;
highEvictionAcWatermarks[tid][pid][cid][1] = acHighThresholdAtI;
double number = distribution(generator);
acHighThresholdAtINew += number * highEvictionDelta;
std::normal_distribution<double> randDistribution(0.0, 1.0);
double randoNum = randDistribution(generator);

if (acLatencies[tid][pid][cid][0] <
acLatencies[tid][pid][cid][1]) { // if current latency reduced
// then increase threshold to increase eviction
// acHighThresholdAtINew+= number*highEvictionDelta;
highEvictionAcWatermarks[tid][pid][cid][0] = acHighThresholdAtINew;
highEvictionAcWatermarks[tid][pid][cid][1] = acHighThresholdAtI;
highEvictionAcWatermarks[tid][pid][cid][2] = acHighThresholdAtIMinus1;
}
//rand boundary,
float diff = acLatencies[tid][pid][cid][0] - acLatencies[tid][pid][cid][1];
//calculate metropolis acceptance criterion
auto t = initial_latency / ( (float) tid + 1);
}
// rand boundary,
float diff =
acLatencies[tid][pid][cid][0] - acLatencies[tid][pid][cid][1];
// calculate metropolis acceptance criterion
auto t = initial_latency / ((float)tid + 1);
float metropolis = exp(-abs(diff) / t);
if (diff < 0 || randoNum < metropolis){
//acHighThresholdAtINew-= number*highEvictionDelta;
highEvictionAcWatermarks[tid][pid][cid][0]=acHighThresholdAtINew;
highEvictionAcWatermarks[tid][pid][cid][1] = acHighThresholdAtI;
if (diff < 0 || randoNum < metropolis) {
// acHighThresholdAtINew-= number*highEvictionDelta;
highEvictionAcWatermarks[tid][pid][cid][0] = acHighThresholdAtINew;
highEvictionAcWatermarks[tid][pid][cid][1] = acHighThresholdAtI;
highEvictionAcWatermarks[tid][pid][cid][2] = acHighThresholdAtIMinus1;
}

acHighThresholdAtINew = std::max(acHighThresholdAtINew, lowEvictionAcWatermark); // high threshold cannot be less than the low threshold
auto CurrentItemsPercent=100-acFree;
auto toFreeMemPercent=CurrentItemsPercent-acHighThresholdAtINew;


acToFreeMemPercents[tid][pid][cid][1] = toFreeMemPercentAtI; //update acToFreeMemPercents
acToFreeMemPercents[tid][pid][cid][0] = toFreeMemPercent; //update acToFreeMemPercents





auto toFreeItems = static_cast<size_t>(toFreeMemPercent * stats.memorySize / stats.allocSize); //calculate number of items to evict for current ac class
batches.push_back(toFreeItems); //append batches



}

}

acHighThresholdAtINew =
std::max(acHighThresholdAtINew,
lowEvictionAcWatermark); // high threshold cannot be less
// than the low threshold
auto CurrentItemsPercent = 100 - acFree;
auto toFreeMemPercent = CurrentItemsPercent - acHighThresholdAtINew;

acToFreeMemPercents[tid][pid][cid][1] =
toFreeMemPercentAtI; // update acToFreeMemPercents
acToFreeMemPercents[tid][pid][cid][0] =
toFreeMemPercent; // update acToFreeMemPercents

auto toFreeItems =
static_cast<size_t>(toFreeMemPercent * stats.memorySize /
stats.allocSize); // calculate number of items to
// evict for current ac class
batches.push_back(toFreeItems); // append batches
}

}

if (batches.size() == 0) {
return batches;
}
auto maxBatch = *std::max_element(batches.begin(), batches.end());
if (maxBatch == 0)
return batches;

std::transform(batches.begin(), batches.end(), batches.begin(), [&](auto numItems){
if (numItems == 0) {
return 0UL;
}
std::transform(
batches.begin(), batches.end(), batches.begin(), [&](auto numItems) {
if (numItems == 0) {
return 0UL;
}

auto cappedBatchSize = maxEvictionBatch * numItems / maxBatch;
if (cappedBatchSize < minEvictionBatch)
return minEvictionBatch;
else
return cappedBatchSize;
});
auto cappedBatchSize = maxEvictionBatch * numItems / maxBatch;
if (cappedBatchSize < minEvictionBatch)
return minEvictionBatch;
else
return cappedBatchSize;
});
return batches;
}


void DynamicFreeThresholdStrategy::calculateLatency(uint64_t acLatency, unsigned int tid, PoolId pid, ClassId cid){

auto best_latency= acLatencies[tid][pid][cid][0];
acLatencies[tid][pid][cid][1]=best_latency;
acLatencies[tid][pid][cid][0]=acLatency;



void DynamicFreeThresholdStrategy::calculateLatency(uint64_t acLatency,
unsigned int tid,
PoolId pid,
ClassId cid) {
auto best_latency = acLatencies[tid][pid][cid][0];
acLatencies[tid][pid][cid][1] = best_latency;
acLatencies[tid][pid][cid][0] = acLatency;
}
} // namespace cachelib
} // namespace facebook
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