Re: [PATCH 01/15] sched/prio: Add a macro named NICE_TO_RLIMIT in prio.h.

From: Dongsheng Yang
Date: Tue Mar 11 2014 - 04:22:34 EST


On 03/11/2014 04:17 PM, Heiko Carstens wrote:
On Tue, Mar 11, 2014 at 12:59:16PM +0800, Dongsheng Yang wrote:
This patch add a macro named NICE_TO_RLIMIT in prio.h to
convert nice value [19,-20] to rlimit style value [1,40].

Signed-off-by: Dongsheng Yang <yangds.fnst@xxxxxxxxxxxxxx>
---
include/linux/sched/prio.h | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/include/linux/sched/prio.h b/include/linux/sched/prio.h
index ac32258..8e78c47 100644
--- a/include/linux/sched/prio.h
+++ b/include/linux/sched/prio.h
@@ -41,4 +41,9 @@
#define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
#define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
+/*
+ * Convert nice value [19,-20] to rlimit style value [1,40].
+ */
+#define NICE_TO_RLIMIT(nice) (MAX_NICE - nice + 1)
Where is MAX_NICE defined? The s390 patch fails to compile.

MAX_NICE is defined in include/linux/sched/prio.h. It is applied in tip tree,
and not in mainline yet.

Also you probably want at least extra braces around the 'nice' usage to
avoid subtle side effects. (or make NICE_TO.. a function, whatever).

Yes, agree. Another question is that I am not sure when I need to use a macro
and when I should use a inline function.

Could you help to give me some sugguestion?

Thanx


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