Use posix_fadvise() on input files, where available.

src/include/config.h.in

@@ -61,6 +61,9 @@
 /* Define to 1 if you have the <minix/config.h> header file. */
 #undef HAVE_MINIX_CONFIG_H
 
+/* Define to 1 if you have the `posix_fadvise' function. */
+#undef HAVE_POSIX_FADVISE
+
 /* Define to 1 if you have the `posix_memalign' function. */
 #undef HAVE_POSIX_MEMALIGN
 

src/pv/file.c

@@ -165,6 +165,11 @@ unsigned long long pv_calc_total_size(pvstate_t state)
 			return total;
 		}
 
+#if HAVE_POSIX_FADVISE
+		/* Advise the OS that we will only be reading sequentially. */
+		(void) posix_fadvise(fd, 0, 0, POSIX_FADV_SEQUENTIAL);
+#endif
+
 		while (1) {
 			unsigned char scanbuf[1024];
 			int numread, j;
@@ -275,6 +280,7 @@ int pv_next_file(pvstate_t state, int filenum, int oldfd)
 	if (0 == strcmp(state->input_files[filenum], "-")) {
 		state->current_file = "(stdin)";
 	}
+
 #ifdef O_DIRECT
 	/*
 	 * Set or clear O_DIRECT on the file descriptor.

src/pv/loop.c

@@ -114,6 +114,12 @@ int pv_main_loop(pvstate_t state)
 			pv_crs_fini(state);
 		return state->exit_status;
 	}
+
+#if HAVE_POSIX_FADVISE
+	/* Advise the OS that we will only be reading sequentially. */
+	(void) posix_fadvise(fd, 0, 0, POSIX_FADV_SEQUENTIAL);
+#endif
+
 #ifdef O_DIRECT
 	/*
 	 * Set or clear O_DIRECT on the output.