当我编译下面的代码时,我收到警告:
src/parallel_hashing.cpp(50): warning #3218: *MIC* class/struct may fail when offloaded because this field is misaligned or contains data that is misaligned __declspec(align(64)) list<HashEntry> mChains[TABLE_SIZE];
^
虽然我认为我已经注意了所需的所有路线。 当我执行它时,我得到一个分段错误。
有谁知道我怎么能让它运作?
代码:
#pragma offload_attribute(push, target(mic))
#include <stdio.h>
#include <stdlib.h>
#include <omp.h>
#include <list>
#include <queue>
#define TABLE_SIZE 3019
#define NUM_OF_THREADS 60
#define HASHINH_PRIME 2654435761
using namespace std;
int Hash(int key)
{
return (HASHINH_PRIME * key) % TABLE_SIZE;
}
class __declspec(align(64)) HashEntry
{
private:
unsigned int mKey;
int mDummy[5];
public:
//Ctor
HashEntry(unsigned int key)
{
mKey = key;
for (int i = 0; i < 5; i++)
{
mDummy[i] = key + i;
}
}
unsigned int GetKey()
{
return mKey;
}
};
class HashTable
{
private:
unsigned int mMaxChainLength;
__declspec(align(64)) list<HashEntry> mChains[TABLE_SIZE];
void UpdateMaxChainLength()
{
int newMaxChainLength = 0;
for (int i = 0; i < TABLE_SIZE; i++)
{
int currentLength = mChains[i].size();
if (currentLength > newMaxChainLength)
{
newMaxChainLength = currentLength;
}
}
mMaxChainLength = newMaxChainLength;
}
list<HashEntry>* GetChain(unsigned int key)
{
return &mChains[Hash(key)];
}
public:
HashTable()
{
mMaxChainLength = 0;
}
unsigned int GetMaxChainLength()
{
return mMaxChainLength;
}
void InsertKey(unsigned int key)
{
//create a new entry with the key
HashEntry newEntry = HashEntry(key);
//get the specific chain
list<HashEntry>* chain = GetChain(key);
//insert the new entry to the chain
chain->insert(chain->end(), newEntry);
//update mMaxChainLength if needed
if (chain->size() > mMaxChainLength)
mMaxChainLength = chain->size();
}
void DeleteKey(unsigned int key)
{
//get the specific chain
list<HashEntry>* chain = GetChain(key);
list<HashEntry>::iterator it = chain->begin();
while (it != chain->end() && it->GetKey() != key)
{
it++;
}
if (it != chain->end())
{
chain->erase(it);
//update mMaxChainLength if the chain (before delete of key) was in the size of mMaxChainLength
if (chain->size() == mMaxChainLength - 1)
UpdateMaxChainLength();
}
}
bool SearchKey(unsigned int key)
{
//get the specific chain
list<HashEntry>* chain = GetChain(key);
list<HashEntry>::iterator it = chain->begin();
while (it != chain->end() && it->GetKey() != key)
{
it++;
}
return (it != chain->end());
}
};
HashTable mCoreTables[NUM_OF_THREADS];
#pragma offload_attribute(pop)
void CreateTables()
{
//parallelize via OpenMP on MIC
#pragma offload target(mic)
#pragma omp parallel num_threads(NUM_OF_THREADS)
{
int core = omp_get_thread_num();
for (int i=0; i<100; i++)
{
mCoreTables[core].InsertKey(i); //for example
}
}
}
int main()
{
omp_set_nested(1);
omp_set_max_active_levels(2);
omp_set_num_threads(NUM_OF_THREADS);
CreateTables();
}
答案 0 :(得分:0)
您提出了稍微宽泛的问题:如何在STL容器中对齐数据。
回答:考虑使用
boost::alignment::aligned_allocator
..对齐数据成员。也不要忘记 -DBOOST_ALIGN 。
阅读更多here(第10 - 13页提供有关您问题的更多详细信息)