Change top to display RSS instead of VSZ.
By Alexander Shishkin <ext-alexander.shishkin@nokia.com>

Ported to BusyBox 1.19 by Dennis Groenen <tj.groenen@gmail.com> - 2011-08-19
---

--- a/procps/top.c
+++ b/procps/top.c
@@ -54,7 +54,7 @@
 
 
 typedef struct top_status_t {
-	unsigned long vsz;
+	unsigned long rss;
 #if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
 	unsigned long ticks;
 	unsigned pcpu; /* delta of ticks */
@@ -166,8 +166,8 @@ static int pid_sort(top_status_t *P, top
 static int mem_sort(top_status_t *P, top_status_t *Q)
 {
 	/* We want to avoid unsigned->signed and truncation errors */
-	if (Q->vsz < P->vsz) return -1;
-	return Q->vsz != P->vsz; /* 0 if ==, 1 if > */
+	if (Q->rss < P->rss) return -1;
+	return Q->rss != P->rss; /* 0 if ==, 1 if > */
 }
 
 
@@ -538,7 +538,7 @@ static NOINLINE void display_process_lis
 
 	/* what info of the processes is shown */
 	printf(OPT_BATCH_MODE ? "%.*s" : "\033[7m%.*s\033[0m", scr_width,
-		"  PID  PPID USER     STAT   VSZ %VSZ"
+		"  PID  PPID USER     STAT   RSS %MEM"
 		IF_FEATURE_TOP_SMP_PROCESS(" CPU")
 		IF_FEATURE_TOP_CPU_USAGE_PERCENTAGE(" %CPU")
 		" COMMAND");
@@ -556,7 +556,7 @@ static NOINLINE void display_process_lis
 # define FMT "%4u%%"
 #endif
 	/*
-	 * %VSZ = s->vsz/MemTotal
+	 * %MEM = s->vsz/MemTotal
 	 */
 	pmem_shift = BITS_PER_INT-11;
 	pmem_scale = UPSCALE*(1U<<(BITS_PER_INT-11)) / total_memory;
@@ -607,16 +607,16 @@ static NOINLINE void display_process_lis
 	s = top;
 	while (--lines_rem >= 0) {
 		unsigned col;
-		CALC_STAT(pmem, (s->vsz*pmem_scale + pmem_half) >> pmem_shift);
+		CALC_STAT(pmem, (s->rss*pmem_scale + pmem_half) >> pmem_shift);
 #if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
 		CALC_STAT(pcpu, (s->pcpu*pcpu_scale + pcpu_half) >> pcpu_shift);
 #endif
 
-		if (s->vsz >= 100000)
-			sprintf(vsz_str_buf, "%6ldm", s->vsz/1024);
+		if (s->rss >= 100000)
+			sprintf(vsz_str_buf, "%6ldm", s->rss/1024);
 		else
-			sprintf(vsz_str_buf, "%7ld", s->vsz);
-		/* PID PPID USER STAT VSZ %VSZ [%CPU] COMMAND */
+			sprintf(vsz_str_buf, "%7ld", s->rss);
+		/* PID PPID USER STAT RSS %MEM %CPU COMMAND */
 		col = snprintf(line_buf, scr_width,
 				"\n" "%5u%6u %-8.8s %s%s" FMT
 				IF_FEATURE_TOP_SMP_PROCESS(" %3d")
@@ -1109,7 +1109,7 @@ int top_main(int argc UNUSED_PARAM, char
 				top = xrealloc_vector(top, 6, ntop++);
 				top[n].pid = p->pid;
 				top[n].ppid = p->ppid;
-				top[n].vsz = p->vsz;
+				top[n].rss = p->rss;
 #if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
 				top[n].ticks = p->stime + p->utime;
 #endif