94 lines
3.2 KiB
C++
94 lines
3.2 KiB
C++
/* vim: tabstop=2 shiftwidth=2 expandtab textwidth=80 linebreak wrap
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*
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* Copyright 2012 Matthew McCormick
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* Copyright 2015 Pawel 'l0ner' Soltys
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <sstream>
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#include <fstream>
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#include <sys/sysinfo.h>
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#include "memory.h"
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#include "conversions.h"
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void mem_status( MemoryStatus & status )
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{
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std::string line;
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std::string substr;
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size_t substr_start;
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size_t substr_len;
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unsigned int total_mem;
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unsigned int used_mem;
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/* Since linux uses some RAM for disk caching, the actuall used ram is lower
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* than what sysinfo(), top or free reports. htop reports the usage in a
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* correct way. The memory used for caching doesn't count as used, since it
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* can be freed in any moment. Usually it hapens automatically, when an
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* application requests memory.
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* In order to calculate the ram that's actually used we need to use the
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* following formula:
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* total_ram + shmem - free_ram - buffered_ram - cached_ram - srclaimable
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*
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* example data, junk removed, with comments added:
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*
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* MemTotal: 61768 kB old
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* MemFree: 1436 kB old
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* MemAvailable ????? kB ??
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* MemShared: 0 kB old (now always zero; not calculated)
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* Buffers: 1312 kB old
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* Cached: 20932 kB old
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* SwapTotal: 122580 kB old
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* SwapFree: 60352 kB old
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*/
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std::ifstream memory_info("/proc/meminfo");
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while( std::getline( memory_info, line ) )
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{
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substr_start = 0;
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substr_len = line.find_first_of( ':' );
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substr = line.substr( substr_start, substr_len );
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substr_start = line.find_first_not_of( " ", substr_len + 1 );
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substr_len = line.find_first_of( 'k' ) - substr_start;
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if( substr.compare( "MemTotal" ) == 0 )
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{
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// get total memory
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total_mem = stol( line.substr( substr_start, substr_len ) );
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}
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else if( substr.compare( "MemFree" ) == 0 )
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{
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used_mem = total_mem - stol( line.substr( substr_start, substr_len ) );
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}
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else if( substr.compare( "Shmem" ) == 0 )
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{
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used_mem += stol( line.substr( substr_start, substr_len ) );
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}
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else if( substr.compare( "Buffers" ) == 0 ||
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substr.compare( "Cached" ) == 0 ||
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substr.compare( "SReclaimable" ) == 0 )
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{
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used_mem -= stol( line.substr( substr_start, substr_len ) );
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}
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}
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// we want megabytes on output, but since the values already come as
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// kilobytes we need to divide them by 1024 only once, thus we use
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// KILOBYTES
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status.used_mem = convert_unit(static_cast< float >( used_mem ), MEGABYTES, KILOBYTES);
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status.total_mem = convert_unit(static_cast< float >( total_mem ), MEGABYTES, KILOBYTES);
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}
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