** Package changed: linux-hwe (Ubuntu) => linux (Ubuntu)
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https://bugs.launchpad.net/bugs/1713029
Title:
Statistics of IO using is incorrect
Status in linux package in Ubuntu:
New
Bug description:
Each one second, my program reads /sys/block/$DEVICE/stat.
It substracts previously saved values, then saves current values, so I know
the hdd activity.
But sometimes (once in 7 days) I've got too big values for sda (between last
and current ones) (for example 5GB/second, 19GB/second, etc...).
sudo lshw -class disk
*-disk
description: ATA Disk
product: SPCC Solid State
physical id: 0.0.0
bus info: scsi@2:0.0.0
logical name: /dev/sda
version: 08.2
serial: EB84075517B200427436
size: 111GiB (120GB)
capabilities: partitioned partitioned:dos
configuration: ansiversion=5 logicalsectorsize=512 sectorsize=512
signature=d01f3b8e
Also I've written the script for monitoring the statistics
#!/bin/bash
while (true) do
str=`date`" $(cat /sys/block/sda/stat)"
echo $str >> log.txt
sleep 10;
done
And got this values
Fr Jul 28 07:39:38 MSK 2017 2368466 475339 105223134 1362848 5753154 7692148
661424840 31319540 0 4790052 32687100
Fr Jul 28 07:39:48 MSK 2017 2368466 475339 105223134 1362848 5753170 7692160
661425104 31319548 0 4790060 32687108
Fr Jul 28 07:39:58 MSK 2017 2368466 475339 105223134 1362848 5753174 7692162
661425152 31319556 0 4790068 32687116
Fr Jul 28 07:40:08 MSK 2017 2369133 475339 105228750 1363380 5771079 7694395
706209560 31324696 0 4795572 32692780
Fr Jul 28 07:40:18 MSK 2017 2369133 475339 105228750 1363380 5771087 7694431
706209960 31324708 0 4795584 32692792
Fr Jul 28 07:40:28 MSK 2017 2369133 475339 105228750 1363380 5771091 7694433
706210008 31324716 0 4795592 32692800
Fr Jul 28 07:40:38 MSK 2017 2369133 475339 105228750 1363380 5771244 7694714
706213528 31325052 0 4795604 32693136
You can see that the difference (3,4 lines) is very big between
706209560 and 661425152, my ssd can read 250 Mb/sec, but not 5 Gb/sec.
Also you can use this program for monitoring (g++ -std=c++14 name.cpp)
#include <iostream>
#include <fstream>
#include <regex>
#include <tuple>
#include <chrono>
#include <thread>
#include <cstdint>
const int HDD_READ_POS = 2;
const int HDD_WRITE_POS = 6;
const int UNIX_SECTOR_SIZE = 512;
uint64_t prevRead = static_cast<uint64_t>(0);
uint64_t prevWrite = static_cast<uint64_t>(0);
std::tuple<uint64_t, uint64_t> hddStatus(const std::string &name="sda")
{
std::ifstream in("/sys/block/"+name+"/stat");
auto readVal_ = static_cast<uint64_t>(0);
auto writeVal_= static_cast<uint64_t>(0);
if ( ! in.is_open() ) {
return std::tuple<uint64_t, uint64_t> (readVal_, writeVal_);
}
std::string line;
std::regex rgx ( "\\d+" );
std::regex_token_iterator<std::string::iterator> end;
while (std::getline(in, line) ){
std::regex_token_iterator<std::string::iterator> iter( line.begin(),
line.end(), rgx, 0 );
int pos_ = 0 ;
while ( iter != end ) {
if ( pos_ == HDD_READ_POS){
readVal_ = std::stoul( *iter ) ;
}
if ( pos_ == HDD_WRITE_POS){
writeVal_ = std::stoul( *iter ) ;
}
++iter;
++pos_;
}
}
return std::tuple<uint64_t, uint64_t> (readVal_, writeVal_);
}
void init()
{
auto values = hddStatus();
prevRead = std::get<0>( values ) * UNIX_SECTOR_SIZE;
prevWrite = std::get<1>( values ) * UNIX_SECTOR_SIZE;
}
int main(int argc, char const *argv[])
{
init();
while(true){
std::ofstream stat("statistics.txt", std::fstream::out |
std::fstream::app);
if ( stat.is_open() ){
auto values = hddStatus();
auto read = std::get<0>( values ) * UNIX_SECTOR_SIZE;
auto write = std::get<1>( values ) * UNIX_SECTOR_SIZE;
// stat<<"Current Read: "<< read<<" Write: "<<write<<'\n';
if (read > prevRead){
stat<<"Diff Read: "<< read - prevRead <<'\n';
std::cout<<"Diff Read: "<< read - prevRead <<'\n';
}
if ( write > prevWrite){
stat<<"Diff Write: "<<write - prevWrite <<'\n';
std::cout<<"Diff Write: "<<write - prevWrite <<'\n';
}
prevRead = read;
prevWrite = write;
std::this_thread::sleep_for(std::chrono::seconds(1));
}
}
return 0;
}
ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-4.10.0-32-generic 4.10.0-32.36~16.04.1
ProcVersionSignature: Ubuntu 4.10.0-32.36~16.04.1-generic 4.10.17
Uname: Linux 4.10.0-32-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.10
Architecture: amd64
CurrentDesktop: Unity
Date: Fri Aug 25 13:43:59 2017
InstallationDate: Installed on 2017-04-14 (132 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64
(20160719)
SourcePackage: linux-hwe
UpgradeStatus: No upgrade log present (probably fresh install)
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