provide POSIX_FADV_SEQUENTIAL hint to appropriate utils

Following on from commit dae35bac, 01-03-2010,
"sort: inform the system about our input access pattern"
apply the same hint to all appropriate utils.
This currently gives around a 5% speedup for reading
large files from fast flash devices on GNU/Linux.

* src/base64.c: Call fadvise (..., FADVISE_SEQUENTIAL);
* src/cat.c: Likewise.
* src/cksum.c: Likewise.
* src/comm.c: Likewise.
* src/cut.c: Likewise.
* src/expand.c: Likewise.
* src/fmt.c: Likewise.
* src/fold.c: Likewise.
* src/join.c: Likewise.
* src/md5sum.c: Likewise.
* src/nl.c: Likewise.
* src/paste.c: Likewise.
* src/pr.c: Likewise.
* src/ptx.c: Likewise.
* src/shuf.c: Likewise.
* src/sum.c: Likewise.
* src/tee.c: Likewise.
* src/tr.c: Likewise.
* src/tsort.c: Likewise.
* src/unexpand.c: Likewise.
* src/uniq.c: Likewise.
* src/wc.c: Likewise, unless we don't actually read().

1 files changed, 6 insertions, 0 deletions

diff --git a/src/wc.c b/src/wc.c
index 6df7feddf..a1922baf9 100644
--- a/src/wc.c
+++ b/src/wc.c
@@ -29,6 +29,7 @@
 #include "system.h"
 #include "argv-iter.h"
 #include "error.h"
+#include "fadvise.h"
 #include "mbchar.h"
 #include "physmem.h"
 #include "quote.h"
@@ -211,6 +212,10 @@ wc (int fd, char const *file_x, struct fstatus *fstatus)
     }
   count_complicated = print_words || print_linelength;
 
+  /* Advise the kernel of our access pattern only if we will read().  */
+  if (!count_bytes || count_chars || print_lines || count_complicated)
+    fdadvise (fd, 0, 0, FADVISE_SEQUENTIAL);
+
   /* When counting only bytes, save some line- and word-counting
      overhead.  If FD is a `regular' Unix file, using lseek is enough
      to get its `size' in bytes.  Otherwise, read blocks of BUFFER_SIZE
@@ -238,6 +243,7 @@ wc (int fd, char const *file_x, struct fstatus *fstatus)
         }
       else
         {
+          fdadvise (fd, 0, 0, FADVISE_SEQUENTIAL);
           while ((bytes_read = safe_read (fd, buf, BUFFER_SIZE)) > 0)
             {
               if (bytes_read == SAFE_READ_ERROR)