[3.14] gh-132917: Use /proc/self/status for mem usage info. (GH-133544) (gh-133718)

miss-islington · nascheme · web-flow · commit 8e86f9c3ccbe · 2025-05-08T16:37:59.000-07:00
On Linux, use /proc/self/status for mem usage info. Using smaps_rollup is quite a lot slower and we can get the similar info from /proc/self/status. (cherry picked from commit 751db4e) Co-authored-by: Neil Schemenauer <nas-github@arctrix.com>
diff --git a/Python/gc_free_threading.c b/Python/gc_free_threading.c
@@ -1927,8 +1927,7 @@ get_process_mem_usage(void)
     }
 
 #elif __linux__
-    // Linux, use smaps_rollup (Kernel >= 4.4) for RSS + Swap
-    FILE* fp = fopen("/proc/self/smaps_rollup", "r");
+    FILE* fp = fopen("/proc/self/status", "r");
     if (fp == NULL) {
         return -1;
     }
@@ -1938,11 +1937,11 @@ get_process_mem_usage(void)
     long long swap_kb = -1;
 
     while (fgets(line_buffer, sizeof(line_buffer), fp) != NULL) {
-        if (rss_kb == -1 && strncmp(line_buffer, "Rss:", 4) == 0) {
-            sscanf(line_buffer + 4, "%lld", &rss_kb);
+        if (rss_kb == -1 && strncmp(line_buffer, "VmRSS:", 6) == 0) {
+            sscanf(line_buffer + 6, "%lld", &rss_kb);
         }
-        else if (swap_kb == -1 && strncmp(line_buffer, "Swap:", 5) == 0) {
-            sscanf(line_buffer + 5, "%lld", &swap_kb);
+        else if (swap_kb == -1 && strncmp(line_buffer, "VmSwap:", 7) == 0) {
+            sscanf(line_buffer + 7, "%lld", &swap_kb);
         }
         if (rss_kb != -1 && swap_kb != -1) {
             break; // Found both

Original file line number	Diff line number	Diff line change
`@@ -1927,8 +1927,7 @@ get_process_mem_usage(void)`
`1927`	`1927`	`}`
`1928`	`1928`
`1929`	`1929`	`#elif __linux__`
`1930`		`- // Linux, use smaps_rollup (Kernel >= 4.4) for RSS + Swap`
`1931`		`- FILE* fp = fopen("/proc/self/smaps_rollup", "r");`
	`1930`	`+ FILE* fp = fopen("/proc/self/status", "r");`
`1932`	`1931`	`if (fp == NULL) {`
`1933`	`1932`	`return -1;`
`1934`	`1933`	`}`
`@@ -1938,11 +1937,11 @@ get_process_mem_usage(void)`
`1938`	`1937`	`long long swap_kb = -1;`
`1939`	`1938`
`1940`	`1939`	`while (fgets(line_buffer, sizeof(line_buffer), fp) != NULL) {`
`1941`		`- if (rss_kb == -1 && strncmp(line_buffer, "Rss:", 4) == 0) {`
`1942`		`- sscanf(line_buffer + 4, "%lld", &rss_kb);`
	`1940`	`+ if (rss_kb == -1 && strncmp(line_buffer, "VmRSS:", 6) == 0) {`
	`1941`	`+ sscanf(line_buffer + 6, "%lld", &rss_kb);`
`1943`	`1942`	`}`
`1944`		`- else if (swap_kb == -1 && strncmp(line_buffer, "Swap:", 5) == 0) {`
`1945`		`- sscanf(line_buffer + 5, "%lld", &swap_kb);`
	`1943`	`+ else if (swap_kb == -1 && strncmp(line_buffer, "VmSwap:", 7) == 0) {`
	`1944`	`+ sscanf(line_buffer + 7, "%lld", &swap_kb);`
`1946`	`1945`	`}`
`1947`	`1946`	`if (rss_kb != -1 && swap_kb != -1) {`
`1948`	`1947`	`break; // Found both`