b1e5addfe
Denis Vlasenko
2007-06-10
Subject
top: improve global CPU percentage (smaller & faster code)
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Commit Diff GitHub →
procps/Config.in+2 -2
| @@ -109,11 +109,11 @@ config FEATURE_TOP_CPU_USAGE_PERCENTAGE | |
| Make top display CPU usage for each process. | |
| config FEATURE_TOP_CPU_GLOBAL_PERCENTS | |
| - | bool "Show CPU global usage percentage (adds 1k byte)" |
| + | bool "Show CPU global usage percentage (adds 0.5k byte)" |
| default y | |
| depends on FEATURE_TOP_CPU_USAGE_PERCENTAGE | |
| help | |
| - | Makes top display "CPU: n.n% us n.n% sy n.n% ni..." line. |
| + | Makes top display "CPU: NN% usr NN% sys..." line. |
| config UPTIME | |
| bool "uptime" | |
procps/top.c+14 -6
| @@ -292,8 +292,15 @@ static unsigned long display_generic(int scr_width) | |
| /* | |
| * xxx% = (jif.xxx - prev_jif.xxx) / (jif.total - prev_jif.total) * 100% | |
| */ | |
| - | #define CALC_STAT(xxx) div_t xxx = div(1000 * (jif.xxx - prev_jif.xxx) / total_diff, 10) |
| - | #define SHOW_STAT(xxx) xxx.quot, '0'+xxx.rem |
| + | /* using (unsigned) cast to make multiplication cheaper: */ |
| + | #define CALC_STAT(xxx) unsigned xxx = 100 * (unsigned)(jif.xxx - prev_jif.xxx) / total_diff |
| + | #define SHOW_STAT(xxx) xxx |
| + | #define FMT "%3u%%" |
| + | // We can display fractional percents, but at least in glibc div() is a _function_ |
| + | // and generated code is really awful and big (+0.5k more code): |
| + | //#define CALC_STAT(xxx) div_t xxx = div(1000 * (unsigned)(jif.xxx - prev_jif.xxx) / total_diff, 10) |
| + | //#define SHOW_STAT(xxx) xxx.quot, '0'+xxx.rem |
| + | //#define FMT "%3u.%c%%" |
| unsigned total_diff = (jif.total - prev_jif.total ? : 1); | |
| CALC_STAT(usr); | |
| CALC_STAT(sys); | |
| @@ -305,10 +312,10 @@ static unsigned long display_generic(int scr_width) | |
| //CALC_STAT(steal); | |
| snprintf(scrbuf, scr_width, | |
| - | /* %3u.%c in practice almost never displays "100.0" |
| - | * and thus has implicit leading space: " 99.6" */ |
| - | "CPU:%3u.%c%% us%3u.%c%% sy%3u.%c%% ni%3u.%c%% id%3u.%c%% wa%3u.%c%% hi%3u.%c%% si", |
| - | // %3u.%c%%st", - what is this 'steal' thing? |
| + | /* %3u in practice almost never displays "100" |
| + | * and thus has implicit leading space: " 99" */ |
| + | "CPU:"FMT" usr"FMT" sys"FMT" nice"FMT" idle"FMT" wait"FMT" irq"FMT" softirq", |
| + | // FMT" steal", - what is this 'steal' thing? |
| // I doubt anyone needs to know it | |
| SHOW_STAT(usr), SHOW_STAT(sys), SHOW_STAT(nic), SHOW_STAT(idle), | |
| SHOW_STAT(iowait), SHOW_STAT(irq), SHOW_STAT(softirq) | |
| @@ -317,6 +324,7 @@ static unsigned long display_generic(int scr_width) | |
| puts(scrbuf); | |
| #undef SHOW_STAT | |
| #undef CALC_STAT | |
| + | #undef FMT |
| } | |
| snprintf(scrbuf, scr_width, "Load average: %s", buf); | |