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List:       busybox
Subject:    [PATCH v2 2/2] top: Add 'IRIX mode'
From:       David Laight <David.Laight () ACULAB ! COM>
Date:       2021-11-12 12:51:41
Message-ID: 39474d8b6b3e4ef4b80a9006498a0b80 () AcuMS ! aculab ! com
[Download RAW message or body]

Add IRIX mode to process cpu% calculation.

For historic reasons top has two different ways of calculation the
process cpu% in a multi-cpu system.
Add 'IRIX mode' where a single-threaded process in an infinite loop
shows 100% and a multi-threaded program can exceed 100%.
The default remains 'Solaris mode' (even for -H) where the maximum
cpu% for a single thread is 100/num_cpus.

Signed-off-by: David Laight <david.laight@aculab.com>

---


--- b/top.c	2021-11-12 11:25:43.849264597 +0000
+++ c/top.c	2021-11-12 11:36:49.510234350 +0000
@@ -165,6 +165,7 @@
 #endif
 #if ENABLE_FEATURE_TOP_SMP_CPU
 	smallint smp_cpu_info; /* one/many cpu info lines? */
+	smallint irix_mode;    /* 100% => one cpu busy */
 #endif
 	unsigned lines;  /* screen height */
 #if ENABLE_FEATURE_TOP_INTERACTIVE
@@ -201,6 +202,7 @@
 #define sort_field       (G.sort_field        )
 #define inverted         (G.inverted          )
 #define smp_cpu_info     (G.smp_cpu_info      )
+#define irix_mode        (G.irix_mode         )
 #define initial_settings (G.initial_settings  )
 #define sort_function    (G.sort_function     )
 #define prev_hist        (G.prev_hist         )
@@ -222,8 +224,9 @@
 	OPT_n = (1 << 1),
 	OPT_b = (1 << 2),
 	OPT_H = (1 << 3),
-	OPT_m = (1 << 4),
-	OPT_EOF = (1 << 5), /* pseudo: "we saw EOF in stdin" */
+	OPT_I = (1 << 4),
+	OPT_m = (1 << 5),
+	OPT_EOF = (1 << 6), /* pseudo: "we saw EOF in stdin" */
 };
 #define OPT_BATCH_MODE (option_mask32 & OPT_b)
 
@@ -311,6 +314,13 @@
 	return;
 #else
 	if (!smp_cpu_info) {
+		if (irix_mode && !num_cpus) {
+			jiffy_counts_t dummy_jif;
+			while (read_cpu_jiffy(fp, &dummy_jif) >= 4)
+				num_cpus++;
+			if (!num_cpus)
+				irix_mode = 0;
+		}
 		fclose(fp);
 		return;
 	}
@@ -599,6 +609,27 @@
 	return meminfo[MI_MEMTOTAL];
 }
 
+#if ENABLE_FEATURE_TOP_DECIMALS
+# define UPSCALE 1000
+# define STAT_BUF(buf_name) char buf_name[8];
+# define SHOW_STAT(name, buf) fmt_proc_pc(name, buf)
+# define FMT "%s"
+static NOINLINE const char *fmt_proc_pc(unsigned value, char *buf)
+{
+	if (value >= 1000)
+		snprintf(buf, 16, "%5u", value/10);
+	else
+		snprintf(buf, 16, "%3u.%c", value/10, '0' + (value % 10));
+	return buf;
+}
+
+#else
+# define UPSCALE 100
+# define STAT_BUF(buf_name)
+# define SHOW_STAT(name, buf) name
+# define FMT "%4u%%"
+#endif
+
 static NOINLINE void display_process_list(int lines_rem, int scr_width)
 {
 	top_status_t *s;
@@ -615,21 +646,13 @@
 		" COMMAND");
 	lines_rem--;
 
-#if ENABLE_FEATURE_TOP_DECIMALS
-# define UPSCALE 1000
-# define CALC_STAT(name, val) div_t name = div((val), 10)
-# define SHOW_STAT(name) name.quot, '0'+name.rem
-# define FMT "%3u.%c"
-#else
-# define UPSCALE 100
-# define CALC_STAT(name, val) unsigned name = (val)
-# define SHOW_STAT(name) name
-# define FMT "%4u%%"
-#endif
-
 #if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
 	/* s->pcpu is in jiffies */
 	delta_jifs = cur_jif.total - prev_jif.total;
+#if ENABLE_FEATURE_TOP_SMP_CPU
+	if (irix_mode && num_cpus)
+		delta_jifs /= num_cpus;
+#endif
 #endif
 
 	/* Ok, all preliminary data is ready, go through the list */
@@ -641,9 +664,11 @@
 		char vsz_str_buf[8];
 		unsigned col;
 
-		CALC_STAT(pmem, (s->vsz * UPSCALE + total_memory/2) / total_memory);
+		unsigned pmem = (s->vsz * UPSCALE + total_memory/2) / total_memory;
+		STAT_BUF(pmem_buf)
 #if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
-		CALC_STAT(pcpu, (s->pcpu * UPSCALE + delta_jifs/2) / delta_jifs);
+		unsigned pcpu = (s->pcpu * UPSCALE + delta_jifs/2) / delta_jifs;
+		STAT_BUF(pcpu_buf)
 #endif
 
 		smart_ulltoa5(s->vsz, vsz_str_buf, " mgtpezy");
@@ -655,9 +680,9 @@
 				" ",
 				s->pid, s->ppid, get_cached_username(s->uid),
 				s->state, vsz_str_buf,
-				SHOW_STAT(pmem)
+				SHOW_STAT(pmem, pmem_buf)
 				IF_FEATURE_TOP_SMP_PROCESS(, s->last_seen_on_cpu)
-				IF_FEATURE_TOP_CPU_USAGE_PERCENTAGE(, SHOW_STAT(pcpu))
+				IF_FEATURE_TOP_CPU_USAGE_PERCENTAGE(, SHOW_STAT(pcpu, pcpu_buf))
 		);
 		if ((int)(scr_width - col) > 1)
 			read_cmdline(line_buf + col, scr_width - col, s->pid, s->comm);
@@ -983,6 +1008,10 @@
 			get_jiffy_counts();
 			continue;
 		}
+		if (c == 'i') {
+			irix_mode ^= 1;
+			continue;
+		}
 #  endif
 # endif
 		break; /* unknown key -> force refresh */
@@ -1069,7 +1098,7 @@
 
 	/* all args are options; -n NUM */
 	make_all_argv_opts(argv); /* options can be specified w/o dash */
-	col = getopt32(argv, "d:n:bHm", &str_interval, &str_iterations);
+	col = getopt32(argv, "d:n:bHIm", &str_interval, &str_iterations);
 	/* NB: -m and -H are accepted even if not configured */
 #if ENABLE_FEATURE_TOPMEM
 	if (col & OPT_m) /* -m (busybox specific) */
@@ -1094,6 +1123,10 @@
 		scan_mask |= PSSCAN_TASKS;
 	}
 #endif
+#if ENABLE_FEATURE_TOP_SMP_CPU
+	if (col & OPT_I)
+		irix_mode = 1;
+#endif
 
 	/* change to /proc */
 	xchdir("/proc");

-
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