mallinfo.3: The 'usmblks' is nowadays always 0

Verified from the course code.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

diff --git a/man3/mallinfo.3 b/man3/mallinfo.3
index 70cea83205ea7c40208c63686757136fe0ad2f27..9ed04caa63194549d2cc17950cdd611fdf9e4106 100644 (file)
--- a/man3/mallinfo.3
+++ b/man3/mallinfo.3
@@ -53,7 +53,7 @@ struct mallinfo {
     int smblks;    /* Number of free fastbin blocks */
     int hblks;     /* Number of mmapped regions */
     int hblkhd;    /* Space allocated in mmapped regions (bytes) */
-    int usmblks;   /* Maximum total allocated space (bytes) */
+    int usmblks;   /* See below */
     int fsmblks;   /* Space in freed fastbin blocks (bytes) */
     int uordblks;  /* Total allocated space (bytes) */
     int fordblks;  /* Total free space (bytes) */
@@ -92,9 +92,11 @@ The number of bytes in blocks currently allocated using
 .BR mmap (2).
 .TP
 .I usmblks
-The "highwater mark" for allocated space\(emthat is,
-the maximum amount of space that was ever allocated.
-This field is maintained only in nonthreading environments.
+This field is unused, and is always 0.
+.\" It seems to have been zero since at least as far back as glibc 2.15
+Historically, it was the "highwater mark" for allocated space\(emthat is,
+the maximum amount of space that was ever allocated (in bytes);
+this field was maintained only in nonthreading environments.
 .TP
 .I fsmblks
 The total number of bytes in fastbin free blocks.