在Linux中如果要監視一個進程的運行情況,如查看它的CPU使用效率和內存使用情況,就需要從系統的/proc目錄的讀取一些系統信息。然后分析得到結果,特別是在嵌入式中的應用程序這個功能就很重要。本文中的代碼是從top命令的源代碼分析中獲得,并做了部分修改,在FC6+GCC4.1調試通過。從這個工程中我也獲得一些感悟。
1. Linux系統很優雅,如果在Windows中做這個功能就需要調用ActiveX控件。而在Linux中只需要讀取文本。
2.想完成什么功能,如果不知道怎么做,就想有沒有沒有其它的軟件有這個功能,如果有,查看它的源代碼就可以了,然后定制自己需要的功能。
3.多想多看多做,學習技術的不二法門。
top命令源代碼下載:http://www.groupsys.com/top/download.shtml
工程下載:
http://www.shnenglu.com/Files/dyj057/mytop.zip
下面是獲得系統CPU和內存情況的代碼:
void
get_system_info(info)
???? struct ?system_info? * info;
{
???? char ?buffer[ 4096 + 1 ];
???? int ?fd,?len;
???? char ? * p;
???? int ?i;
???? /* ?get?load?averages? */
????{
????fd? = ?open( " loadavg " ,?O_RDONLY);
????len? = ?read(fd,?buffer,? sizeof (buffer) - 1 );
????close(fd);
????buffer[len]? = ? ' \0 ' ;
????info -> load_avg[ 0 ]? = ?strtod(buffer,? & p);
????info -> load_avg[ 1 ]? = ?strtod(p,? & p);
????info -> load_avg[ 2 ]? = ?strtod(p,? & p);
????p? = ?skip_token(p);???????????? /* ?skip?running/tasks? */
????p? = ?skip_ws(p);
???? if ?( * p)
????????info -> last_pid? = ?atoi(p);
???? else
????????info -> last_pid? = ? - 1 ;
????}
???? /* ?get?the?cpu?time?info? */
????{
????fd? = ?open( " stat " ,?O_RDONLY);
????len? = ?read(fd,?buffer,? sizeof (buffer) - 1 );
????close(fd);
????buffer[len]? = ? ' \0 ' ;
????p? = ?skip_token(buffer);???????????? /* ?"cpu"? */
????cp_time[ 0 ]? = ?strtoul(p,? & p,? 0 );
????
????cp_time[ 1 ]? = ?strtoul(p,? & p,? 0 );
????cp_time[ 2 ]? = ?strtoul(p,? & p,? 0 );
????cp_time[ 3 ]? = ?strtoul(p,? & p,? 0 );
???? /* ?convert?cp_time?counts?to?percentages? */
????percentages( 4 ,?cpu_states,?cp_time,?cp_old,?cp_diff);
????}
????
???? /* ?get?system?wide?memory?usage? */
????{
???? char ? * p;
????fd? = ?open( " meminfo " ,?O_RDONLY);
????len? = ?read(fd,?buffer,? sizeof (buffer) - 1 );
????close(fd);
????buffer[len]? = ? ' \0 ' ;
???? /* ?be?prepared?for?extra?columns?to?appear?be?seeking
???????to?ends?of?lines? */
????
????p? = ?buffer;
????p? = ?skip_token(p);
????memory_stats[ 0 ]? = ?strtoul(p,? & p,? 10 );? /* ?total?memory? */
????
????p? = ?strchr(p,? ' \n ' );
????p? = ?skip_token(p);
????memory_stats[ 1 ]? = ?strtoul(p,? & p,? 10 );? /* ?free?memory? */
????
????
????p? = ?strchr(p,? ' \n ' );
????p? = ?skip_token(p);
????memory_stats[ 2 ]? = ?strtoul(p,? & p,? 10 );? /* ?buffer?memory? */
????
????p? = ?strchr(p,? ' \n ' );
????p? = ?skip_token(p);
????memory_stats[ 3 ]? = ?strtoul(p,? & p,? 10 );? /* ?cached?memory? */
????
???? for (i? = ? 0 ;?i < ? 8 ?;i ++ )?{
????????p ++ ;
????????p? = ?strchr(p,? ' \n ' );
????}
????
????p? = ?skip_token(p);
????memory_stats[ 4 ]? = ?strtoul(p,? & p,? 10 );? /* ?total?swap? */
????
????p? = ?strchr(p,? ' \n ' );
????p? = ?skip_token(p);
????memory_stats[ 5 ]? = ?strtoul(p,? & p,? 10 );? /* ?free?swap? */
????
????}
???? /* ?set?arrays?and?strings? */
????info -> cpustates? = ?cpu_states;
????info -> memory? = ?memory_stats;
}
get_system_info(info)
???? struct ?system_info? * info;
{
???? char ?buffer[ 4096 + 1 ];
???? int ?fd,?len;
???? char ? * p;
???? int ?i;
???? /* ?get?load?averages? */
????{
????fd? = ?open( " loadavg " ,?O_RDONLY);
????len? = ?read(fd,?buffer,? sizeof (buffer) - 1 );
????close(fd);
????buffer[len]? = ? ' \0 ' ;
????info -> load_avg[ 0 ]? = ?strtod(buffer,? & p);
????info -> load_avg[ 1 ]? = ?strtod(p,? & p);
????info -> load_avg[ 2 ]? = ?strtod(p,? & p);
????p? = ?skip_token(p);???????????? /* ?skip?running/tasks? */
????p? = ?skip_ws(p);
???? if ?( * p)
????????info -> last_pid? = ?atoi(p);
???? else
????????info -> last_pid? = ? - 1 ;
????}
???? /* ?get?the?cpu?time?info? */
????{
????fd? = ?open( " stat " ,?O_RDONLY);
????len? = ?read(fd,?buffer,? sizeof (buffer) - 1 );
????close(fd);
????buffer[len]? = ? ' \0 ' ;
????p? = ?skip_token(buffer);???????????? /* ?"cpu"? */
????cp_time[ 0 ]? = ?strtoul(p,? & p,? 0 );
????
????cp_time[ 1 ]? = ?strtoul(p,? & p,? 0 );
????cp_time[ 2 ]? = ?strtoul(p,? & p,? 0 );
????cp_time[ 3 ]? = ?strtoul(p,? & p,? 0 );
???? /* ?convert?cp_time?counts?to?percentages? */
????percentages( 4 ,?cpu_states,?cp_time,?cp_old,?cp_diff);
????}
????
???? /* ?get?system?wide?memory?usage? */
????{
???? char ? * p;
????fd? = ?open( " meminfo " ,?O_RDONLY);
????len? = ?read(fd,?buffer,? sizeof (buffer) - 1 );
????close(fd);
????buffer[len]? = ? ' \0 ' ;
???? /* ?be?prepared?for?extra?columns?to?appear?be?seeking
???????to?ends?of?lines? */
????
????p? = ?buffer;
????p? = ?skip_token(p);
????memory_stats[ 0 ]? = ?strtoul(p,? & p,? 10 );? /* ?total?memory? */
????
????p? = ?strchr(p,? ' \n ' );
????p? = ?skip_token(p);
????memory_stats[ 1 ]? = ?strtoul(p,? & p,? 10 );? /* ?free?memory? */
????
????
????p? = ?strchr(p,? ' \n ' );
????p? = ?skip_token(p);
????memory_stats[ 2 ]? = ?strtoul(p,? & p,? 10 );? /* ?buffer?memory? */
????
????p? = ?strchr(p,? ' \n ' );
????p? = ?skip_token(p);
????memory_stats[ 3 ]? = ?strtoul(p,? & p,? 10 );? /* ?cached?memory? */
????
???? for (i? = ? 0 ;?i < ? 8 ?;i ++ )?{
????????p ++ ;
????????p? = ?strchr(p,? ' \n ' );
????}
????
????p? = ?skip_token(p);
????memory_stats[ 4 ]? = ?strtoul(p,? & p,? 10 );? /* ?total?swap? */
????
????p? = ?strchr(p,? ' \n ' );
????p? = ?skip_token(p);
????memory_stats[ 5 ]? = ?strtoul(p,? & p,? 10 );? /* ?free?swap? */
????
????}
???? /* ?set?arrays?and?strings? */
????info -> cpustates? = ?cpu_states;
????info -> memory? = ?memory_stats;
}


