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fix an issue with the freeing of data in the cacher

master
Constantin Fürst 12 months ago
parent
f19c069b0f
commit
395d307310
2 changed files with 192 additions and 82 deletions
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  1. 85
      offloading-cacher/main.cpp
  2. 177
      offloading-cacher/offloading-cache.hpp

85
offloading-cacher/main.cpp
View File

@ -3,6 +3,8 @@
#include "offloading-cache.hpp"
offcache::Cache CACHE;
double* GetRandomArray(const size_t size) {
double* array = new double[size];
@ -29,36 +31,91 @@ bool IsEqual(const double* a, const double* b, const size_t size) {
return true;
}
void PerformAccessAndTest(double* src, const size_t size) {
// this is the function that any cache access will go through
// execution policy picks between three options:
// Relaxed may return an invalid (but not nullptr) CacheData
// which can then be validated with WaitOnCompletion()
// Immediate never returns an invalid CacheData structure
// however it may return just the pointer to source
// WaitOnCompletion() will then ensure that the data
// is actually in cache
// ImmediateNoCache behaves the same as Immediate but does never perform
// caching itself so only returns cached version if
// previously cached is available
std::unique_ptr<offcache::CacheData> data_cache = CACHE.Access(
reinterpret_cast<uint8_t *>(src),
size * sizeof(double),
offcache::ExecutionPolicy::Immediate
);
double* cached_imm = reinterpret_cast<double *>(data_cache->GetDataLocation());
// check the value immediately just to see if ram or cache was returned
if (src == cached_imm) {
std::cout << "Caching did not immediately yield different data location." << std::endl;
}
else {
std::cout << "Immediately got different data location." << std::endl;
}
// waits for the completion of the asynchronous caching operation
data_cache->WaitOnCompletion();
// gets the cache-data-location from the struct
double* cached = reinterpret_cast<double *>(data_cache->GetDataLocation());
// tests on the resulting value
if (src == cached) {
std::cout << "Caching did not affect data location." << std::endl;
}
if (IsEqual(src,cached,size)) {
std::cout << "Cached data is correct." << std::endl;
}
else {
std::cout << "Cached data is wrong." << std::endl;
}
}
int main(int argc, char **argv) {
offcache::Cache cache;
// given numa destination and source node and the size of the data
// this function decides on which the data will be placed
// which is used to select the HBM-node for the dst-node if desired
auto cache_policy = [](const int numa_dst_node, const int numa_src_node, const size_t data_size) {
return numa_dst_node;
};
// this function receives the memory source and destination node
// and then decides, on which nodes the copy operation will be split
auto copy_policy = [](const int numa_dst_node, const int numa_src_node) {
return std::vector{ numa_src_node, numa_dst_node };
};
cache.Init(cache_policy,copy_policy);
// initializes the cache with the two policies
CACHE.Init(cache_policy,copy_policy);
// generate the test data
static constexpr size_t data_size = 1024 * 1024;
double* data = GetRandomArray(data_size);
std::unique_ptr<offcache::CacheData> data_cache = cache.Access(reinterpret_cast<uint8_t *>(data), data_size * sizeof(double), offcache::ExecutionPolicy::Relaxed);
std::cout << "--- first access --- " << std::endl;
data_cache->WaitOnCompletion();
PerformAccessAndTest(data, data_size);
double* cached = reinterpret_cast<double *>(data_cache->GetDataLocation());
std::cout << "--- second access --- " << std::endl;
if (data == cached) {
std::cout << "Caching did not affect data location." << std::endl;
}
PerformAccessAndTest(data, data_size);
if (IsEqual(data,cached,data_size)) {
std::cout << "Cached data is correct." << std::endl;
}
else {
std::cout << "Cached data is wrong." << std::endl;
}
std::cout << "--- end of application --- " << std::endl;
}

177
offloading-cacher/offloading-cache.hpp
View File

@ -94,9 +94,14 @@ namespace offcache {
typedef std::vector<int> (CopyPolicy)(const int numa_dst_node, const int numa_src_node);
private:
// mutex for accessing the cache state map
std::shared_mutex cache_mutex_;
std::unordered_map<uint8_t*, CacheData> cache_state_;
// map from [dst-numa-node,map2]
// map2 from [data-ptr,cache-structure]
std::unordered_map<uint8_t, std::unordered_map<uint8_t*, CacheData>> cache_state_;
CachePolicy* cache_policy_function_ = nullptr;
CopyPolicy* copy_policy_function_ = nullptr;
@ -105,6 +110,12 @@ namespace offcache {
void SubmitTask(CacheData* task);
void GetCacheNode(uint8_t* src, const size_t size, int* OUT_DST_NODE, int* OUT_SRC_NODE) const;
void AbortTask(CacheData* task) const;
std::unique_ptr<CacheData> GetFromCache(uint8_t* src, const size_t size);
public:
void Init(CachePolicy* cache_policy_function, CopyPolicy* copy_policy_function);
@ -126,40 +137,29 @@ inline void offcache::Cache::Init(CachePolicy* cache_policy_function, CopyPolicy
// initialize numa library
numa_available();
const int nodes_max = numa_num_configured_nodes();
const bitmask* valid_nodes = numa_get_mems_allowed();
for (int node = 0; node < nodes_max; node++) {
if (numa_bitmask_isbitset(valid_nodes, node)) {
cache_state_.insert({node,{}});
}
}
std::cout << "[-] Cache Initialized" << std::endl;
}
inline std::unique_ptr<offcache::CacheData> offcache::Cache::Access(uint8_t* data, const size_t size, const ExecutionPolicy policy) {
// the best situation is if this data is already cached
// which we check in an unnamed block in which the cache
// is locked for reading to prevent another thread
// from marking the element we may find as unused and
// clearing it
{
std::shared_lock<std::shared_mutex> lock(cache_mutex_);
const auto search = cache_state_.find(data);
if (search != cache_state_.end()) {
if (search->second.size_ == size) {
search->second.active_->store(true);
std::cout << "[+] Found Cached version for 0x" << std::hex << (uint64_t)data << std::dec << std::endl;
std::unique_ptr<CacheData> task = GetFromCache(data, size);
return std::move(std::make_unique<CacheData>(search->second));
}
else {
std::cout << "[!] Found Cached version with size missmatch for 0x" << std::hex << (uint64_t)data << std::dec << std::endl;
cache_state_.erase(search);
}
}
if (task != nullptr) {
return std::move(task);
}
// at this point the requested data is not present in cache
// and we create a caching task for it
auto task = std::make_unique<CacheData>(data, size);
task = std::make_unique<CacheData>(data, size);
if (policy == ExecutionPolicy::Immediate) {
// in intermediate mode the returned task
@ -197,19 +197,12 @@ inline std::unique_ptr<offcache::CacheData> offcache::Cache::Access(uint8_t* dat
}
inline void offcache::Cache::SubmitTask(CacheData* task) {
// obtain numa node of current thread to determine where the data is needed
// get destination numa node for the cache
const int current_cpu = sched_getcpu();
const int current_node = numa_node_of_cpu(current_cpu);
int dst_node = -1;
int src_node = -1;
// obtain node that the given data pointer is allocated on
int data_node = -1;
get_mempolicy(&data_node, NULL, 0, (void*)task->src_, MPOL_F_NODE | MPOL_F_ADDR);
// querry cache policy function for the destination numa node
const int dst_node = cache_policy_function_(current_node, data_node, task->size_);
GetCacheNode(task->src_, task->size_, &dst_node, &src_node);
std::cout << "[+] Allocating " << task->size_ << "B on node " << dst_node << " for " << std::hex << (uint64_t)task->src_ << std::dec << std::endl;
@ -236,7 +229,7 @@ inline void offcache::Cache::SubmitTask(CacheData* task) {
// querry copy policy function for the nodes to use for the copy
const std::vector<int> executing_nodes = copy_policy_function_(dst_node, data_node);
const std::vector<int> executing_nodes = copy_policy_function_(dst_node, src_node);
const size_t task_count = executing_nodes.size();
// each task will copy one fair part of the total size
@ -272,7 +265,7 @@ inline void offcache::Cache::SubmitTask(CacheData* task) {
{
std::unique_lock<std::shared_mutex> lock(cache_mutex_);
const auto state = cache_state_.insert({task->src_, *task});
const auto state = cache_state_[dst_node].emplace(task->src_, *task);
// if state.second is false then no insertion took place
// which means that concurrently whith this thread
@ -283,20 +276,7 @@ inline void offcache::Cache::SubmitTask(CacheData* task) {
if (!state.second) {
std::cout << "[x] Found another cache instance for 0x" << std::hex << (uint64_t)task->src_ << std::dec << std::endl;
// first wait on all copy operations to be completed
task->WaitOnCompletion();
// abort by doing the following steps
// (1) free the allocated memory, (2) remove the "maybe result" as
// we will not run the caching operation, (3) clear the sub tasks
// for the very same reason, (4) set the result to the RAM-location
numa_free(dst, task->size_);
task->incomplete_cache_ = nullptr;
task->cache_->store(task->src_);
std::cout << "[-] Abort completed for 0x" << std::hex << (uint64_t)task->src_ << std::dec << std::endl;
AbortTask(task);
return;
}
@ -346,7 +326,7 @@ offcache::CacheData::CacheData(uint8_t* data, const size_t size) {
src_ = data;
size_ = size;
active_ = new std::atomic<int32_t>();
active_ = new std::atomic<int32_t>(1);
cache_ = new std::atomic<uint8_t*>();
incomplete_cache_ = nullptr;
handlers_ = std::make_unique<std::vector<dml_handler>>();
@ -355,21 +335,25 @@ offcache::CacheData::CacheData(uint8_t* data, const size_t size) {
offcache::CacheData::CacheData(const offcache::CacheData& other) {
std::cout << "[-] Copy Created for CacheData 0x" << std::hex << (uint64_t)other.src_ << std::dec << std::endl;
active_ = other.active_;
const int current_active = active_->fetch_add(1);
src_ = other.src_;
size_ = other.size_;
cache_ = other.cache_;
active_ = other.active_;
incomplete_cache_ = nullptr;
handlers_ = nullptr;
active_->fetch_add(1);
}
offcache::CacheData::~CacheData() {
std::cout << "[-] Destructor for CacheData 0x" << std::hex << (uint64_t)src_ << std::dec << std::endl;
const int32_t v = active_->fetch_sub(1);
// due to fetch_sub returning the preivously held value
// we must subtract one locally to get the current value
const int32_t v = active_->fetch_sub(1) - 1;
// if the returned value is non-positive
// if the returned value is zero or lower
// then we must execute proper deletion
// as this was the last reference
@ -390,7 +374,23 @@ void offcache::CacheData::Deallocate() {
incomplete_cache_ = nullptr;
}
uint8_t *offcache::CacheData::GetDataLocation() const {
void offcache::Cache::GetCacheNode(uint8_t* src, const size_t size, int* OUT_DST_NODE, int* OUT_SRC_NODE) const {
// obtain numa node of current thread to determine where the data is needed
const int current_cpu = sched_getcpu();
const int current_node = numa_node_of_cpu(current_cpu);
// obtain node that the given data pointer is allocated on
*OUT_SRC_NODE = -1;
get_mempolicy(OUT_SRC_NODE, NULL, 0, (void*)src, MPOL_F_NODE | MPOL_F_ADDR);
// querry cache policy function for the destination numa node
*OUT_DST_NODE = cache_policy_function_(current_node, *OUT_SRC_NODE, size);
}
uint8_t* offcache::CacheData::GetDataLocation() const {
return cache_->load();
}
@ -406,16 +406,69 @@ inline void offcache::Cache::Flush() {
{
std::unique_lock<std::shared_mutex> lock(cache_mutex_);
auto it = cache_state_.begin();
for (auto& nc : cache_state_) {
auto it = nc.second.begin();
while (it != cache_state_.end()) {
while (it != nc.second.end()) {
if (it->second.Active() == false) {
cache_state_.erase(it);
it = cache_state_.begin();
nc.second.erase(it);
it = nc.second.begin();
}
else {
it++;
}
}
}
}
}
void offcache::Cache::AbortTask(offcache::CacheData *task) const {
// first wait on all copy operations to be completed
task->WaitOnCompletion();
// abort by doing the following steps
// (1) free the allocated memory, (2) remove the "maybe result" as
// we will not run the caching operation, (3) clear the sub tasks
// for the very same reason, (4) set the result to the RAM-location
numa_free(task->incomplete_cache_, task->size_);
task->incomplete_cache_ = nullptr;
task->cache_->store(task->src_);
std::cout << "[-] Abort completed for 0x" << std::hex << (uint64_t)task->src_ << std::dec << std::endl;
}
std::unique_ptr<offcache::CacheData> offcache::Cache::GetFromCache(uint8_t* src, const size_t size) {
// the best situation is if this data is already cached
// which we check in an unnamed block in which the cache
// is locked for reading to prevent another thread
// from marking the element we may find as unused and
// clearing it
int dst_node = -1;
int src_node = -1;
GetCacheNode(src, size, &dst_node, &src_node);
std::shared_lock<std::shared_mutex> lock(cache_mutex_);
const auto search = cache_state_[dst_node].find(src);
if (search != cache_state_[dst_node].end()) {
if (search->second.size_ == size) {
search->second.active_->store(true);
std::cout << "[+] Found Cached version for 0x" << std::hex << (uint64_t)src << std::dec << std::endl;
return std::move(std::make_unique<CacheData>(search->second));
}
else {
std::cout << "[!] Found Cached version with size missmatch for 0x" << std::hex << (uint64_t)src << std::dec << std::endl;
cache_state_[dst_node].erase(search);
}
}
return nullptr;
}
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