top: add config option and code for global CPU % display

4 files changed, 70 insertions, 20 deletions

diff --git a/docs/keep_data_small.txt b/docs/keep_data_small.txt
index f88fe07b0..3ddbd81a4 100644
--- a/docs/keep_data_small.txt
+++ b/docs/keep_data_small.txt
@@ -43,6 +43,16 @@ takes 55k of memory on 64-bit x86 kernel.
 
 On 32-bit kernel we need ~26k per applet.
 
+Script:
+
+i=1000; while test $i != 0; do
+        echo -n .
+        busybox sleep 30 &
+        i=$((i - 1))
+done
+echo
+wait
+
 (Data from NOMMU arches are sought. Provide 'size busybox' output too)
 
 
diff --git a/libbb/procps.c b/libbb/procps.c
index be0d61bd3..1e2495a5a 100644
--- a/libbb/procps.c
+++ b/libbb/procps.c
@@ -79,8 +79,15 @@ const char* get_cached_groupname(gid_t gid)
 
 static int read_to_buf(const char *filename, void *buf)
 {
-        ssize_t ret;
-        ret = open_read_close(filename, buf, PROCPS_BUFSIZE-1);
+        int fd;
+        /* open_read_close() would do two reads, checking for EOF.
+         * When you have 10000 /proc/$NUM/stat to read, it isn't desirable */
+        ssize_t ret = -1;
+        fd = open(filename, O_RDONLY);
+        if (fd >= 0) {
+                ret = read(fd, buf, PROCPS_BUFSIZE-1);
+                close(fd);
+        }
         ((char *)buf)[ret > 0 ? ret : 0] = '\0';
         return ret;
 }
diff --git a/procps/Config.in b/procps/Config.in
index e58b89f85..cd46a3448 100644
--- a/procps/Config.in
+++ b/procps/Config.in
@@ -102,11 +102,18 @@ config TOP
           system.
 
 config FEATURE_TOP_CPU_USAGE_PERCENTAGE
-        bool "Support showing CPU usage percentage (add 2k bytes)"
+        bool "Show CPU per-process usage percentage (adds 2k bytes)"
         default y
         depends on TOP
         help
-          Make top display CPU usage.
+          Make top display CPU usage for each process.
+
+config FEATURE_TOP_CPU_GLOBAL_PERCENTS
+        bool "Show CPU global usage percentage (adds 1k 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.
 
 config UPTIME
         bool "uptime"
diff --git a/procps/top.c b/procps/top.c
index 948ab0315..6d8dfd880 100644
--- a/procps/top.c
+++ b/procps/top.c
@@ -221,7 +221,6 @@ static unsigned long display_generic(int scr_width)
         char scrbuf[80];
         char *end;
         unsigned long total, used, mfree, shared, buffers, cached;
-        unsigned int needs_conversion = 1;
 
         /* read memory info */
         fp = xfopen("meminfo", "r");
@@ -240,14 +239,20 @@ static unsigned long display_generic(int scr_width)
                 fgets(buf, sizeof(buf), fp);    /* skip first line */
 
                 fscanf(fp, "Mem: %lu %lu %lu %lu %lu %lu",
-                   &total, &used, &mfree, &shared, &buffers, &cached);
+                        &total, &used, &mfree, &shared, &buffers, &cached);
+                /* convert to kilobytes */
+                used /= 1024;
+                mfree /= 1024;
+                shared /= 1024;
+                buffers /= 1024;
+                cached /= 1024;
+                total /= 1024;
         } else {
                 /*
                  * Revert to manual parsing, which incidentally already has the
                  * sizes in kilobytes. This should be safe for both 2.4 and
                  * 2.6.
                  */
-                needs_conversion = 0;
 
                 fscanf(fp, "MemFree: %lu %s\n", &mfree, buf);
 
@@ -273,16 +278,6 @@ static unsigned long display_generic(int scr_width)
         if (end) end = strchr(end+1, ' ');
         if (end) *end = '\0';
 
-        if (needs_conversion) {
-                /* convert to kilobytes */
-                used /= 1024;
-                mfree /= 1024;
-                shared /= 1024;
-                buffers /= 1024;
-                cached /= 1024;
-                total /= 1024;
-        }
-
         /* output memory info and load average */
         /* clear screen & go to top */
         if (scr_width > sizeof(scrbuf))
@@ -293,8 +288,39 @@ static unsigned long display_generic(int scr_width)
 
         printf(OPT_BATCH_MODE ? "%s\n" : "\e[H\e[J%s\n", scrbuf);
 
+        if (ENABLE_FEATURE_TOP_CPU_GLOBAL_PERCENTS) {
+                /*
+                 * 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
+                unsigned total_diff = (jif.total - prev_jif.total ? : 1);
+                CALC_STAT(usr);
+                CALC_STAT(sys);
+                CALC_STAT(nic);
+                CALC_STAT(idle);
+                CALC_STAT(iowait);
+                CALC_STAT(irq);
+                CALC_STAT(softirq);
+                //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?
+                        // 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)
+                        //, SHOW_STAT(steal)
+                );
+                puts(scrbuf);
+#undef SHOW_STAT
+#undef CALC_STAT
+        }
+
         snprintf(scrbuf, scr_width, "Load average: %s", buf);
-        printf("%s\n", scrbuf);
+        puts(scrbuf);
 
         return total;
 }
@@ -479,7 +505,7 @@ int top_main(int argc, char **argv)
                 procps_status_t *p = NULL;
 
                 /* Default to 25 lines - 5 lines for status */
-                lines = 24 - 3;
+                lines = 24 - 3 USE_FEATURE_TOP_CPU_GLOBAL_PERCENTS( - 1);
                 col = 79;
 #if ENABLE_FEATURE_USE_TERMIOS
                 get_terminal_width_height(0, &col, &lines);
@@ -487,7 +513,7 @@ int top_main(int argc, char **argv)
                         sleep(interval);
                         continue;
                 }
-                lines -= 3;
+                lines -= 3 USE_FEATURE_TOP_CPU_GLOBAL_PERCENTS( + 1);
 #endif /* FEATURE_USE_TERMIOS */
 
                 /* read process IDs & status for all the processes */