如何減少從一個增強鏈到另一個增強鏈的延遲

Question

假設存在多個增強鏈share_ptr存儲在向量m_poStrands中。而tJobType是enum表示不同類型的作業。 我發現在一條鏈（JOBA）中發佈工作以調用另一條鏈的onJob（JOBB）的時間差約爲50毫秒。 我想知道是否有任何方法來縮短時差。

void postJob(tJobType oType, UINT8* pcBuffer, size_t iSize) 
{ 
//... 
    m_poStrands[oType]->post(boost::bind(&onJob, this, oType, pcDestBuffer, iSize)); 
} 

void onJob(tJobType oType, UINT8* pcBuffer, size_t iSize) 
{ 
     if (oType == JOBA) 
     { 
     //.... 
     struct timeval sTV; 
    gettimeofday(&sTV, 0); 
    memcpy(pcDestBuffer, &sTV, sizeof(sTV)); 
    pcDestBuffer += sizeof(sTV); 
    iSize += sizeof(sTV); 

    memcpy(pcDestBuffer, pcBuffer, iSize); 

     m_poStrands[JOBB]->(boost::bind(&onJob, this, JOBB, pcDestBuffer, iSize)); 
     } 
     else if (oType == JOBB) 
     { 
     // get the time from buffer 
     // and calculate the dime diff 
     struct timeval eTV; 
     gettimeofday(&eTV, 0); 
     } 
} 

Answer 1

您的等待時間大概是從memcpy來臨了您的gettimeofday秒之間。這裏是我在我的機器上運行的一個示例程序（2 GHz核心2雙核）。我得到了幾千納秒。所以幾微秒。我懷疑你的系統運行速度比我的慢4個數量級。我看到它運行的最差的兩次測試之一是100微秒。我試着儘可能使代碼貼近代碼。

#include <boost/asio.hpp> 
#include <boost/chrono.hpp> 
#include <boost/bind.hpp> 
#include <boost/thread.hpp> 
#include <iostream> 

struct Test { 
    boost::shared_ptr<boost::asio::strand>* strands; 
    boost::chrono::high_resolution_clock::time_point start; 
    int id; 

    Test(int i, boost::shared_ptr<boost::asio::strand>* strnds) 
     : id(i), 
      strands(strnds) 
    { 
     strands[0]->post(boost::bind(&Test::callback,this,0)); 
    } 

    void callback(int i) { 
     if (i == 0) { 
      start = boost::chrono::high_resolution_clock::now(); 
      strands[1]->post(boost::bind(&Test::callback,this,1)); 
     } else { 
      boost::chrono::nanoseconds sec = boost::chrono::high_resolution_clock::now() - start; 
      std::cout << "test " << id << " took " << sec.count() << " ns" << std::endl; 
     } 
    } 
}; 

int main() { 
    boost::asio::io_service io_service_; 
    boost::shared_ptr<boost::asio::strand> strands[2]; 
    strands[0] = boost::shared_ptr<boost::asio::strand>(new boost::asio::strand(io_service_)); 
    strands[1] = boost::shared_ptr<boost::asio::strand>(new boost::asio::strand(io_service_)); 
    boost::thread t1 (boost::bind(&boost::asio::io_service::run, &io_service_)); 
    boost::thread t2 (boost::bind(&boost::asio::io_service::run, &io_service_)); 
    Test test1 (1, strands); 
    Test test2 (2, strands); 
    t1.join(); 
    t2.join(); 
}