lkml.org 
[lkml]   [2010]   [Sep]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
SubjectRe: [PATCH] ida: fix up bitmap size calculation
Date
Namhyung Kim <namhyung@gmail.com> writes:
> Got it. :-) I'll prepare new patch with that comment, then.
> Thank you for the explanation.

How about this?

From 38866b19cdbf03d133c54a1f3b7d48279bdd4177 Mon Sep 17 00:00:00 2001
From: Namhyung Kim <namhyung@gmail.com>
Date: Fri, 3 Sep 2010 02:44:47 +0900
Subject: [PATCH] ida: document IDA_BITMAP_LONGS calculation

IDA_BITMAP_LONGS value is calculated take into account struct ida_bitmap
not to waste memory space. Comment it.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
---
include/linux/idr.h | 9 ++++++++-
1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/include/linux/idr.h b/include/linux/idr.h
index e968db7..7807e4b 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -119,9 +119,16 @@ void idr_init(struct idr *idp);
* pointer isn't necessary.
*/
#define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
+/*
+ * -1 is needed here to fit total chunk size into 128 bytes because
+ * struct ida_bitmap consists of nr_busy and bitmap. Since it is
+ * allocated by kmalloc(), chunk size should be matched with kmalloc
+ * size so that it will not waste memory.
+ */
#define IDA_BITMAP_LONGS (128 / sizeof(long) - 1)
-#define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
+#define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)

+/* IDA bitmap chunk */
struct ida_bitmap {
long nr_busy;
unsigned long bitmap[IDA_BITMAP_LONGS];
--
1.7.2.2


\
 
 \ /
  Last update: 2010-09-02 20:09    [W:0.057 / U:1.188 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site