[PATCH] ifdef ->rchar, ->wchar, ->syscr, ->syscw from task_struct

They are fat: 4x8 bytes in task_struct.
They are uncoditionally updated in every fork, read, write and sendfile.
They are used only if you have some "extended acct fields feature".

And please, please, please, read(2) knows about bytes, not characters,
why it is called "rchar"?

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Jay Lan <jlan@engr.sgi.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index d57118da73ff..80284eb488ce 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1038,10 +1038,12 @@ static struct task_struct *copy_process(unsigned long clone_flags,
         p->utime = cputime_zero;
         p->stime = cputime_zero;
         p->sched_time = 0;
+#ifdef CONFIG_TASK_XACCT
         p->rchar = 0;           /* I/O counter: bytes read */
         p->wchar = 0;           /* I/O counter: bytes written */
         p->syscr = 0;           /* I/O counter: read syscalls */
         p->syscw = 0;           /* I/O counter: write syscalls */
+#endif
         task_io_accounting_init(p);
         acct_clear_integrals(p);