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authorDavid Howells <dhowells@redhat.com>2006-12-08 02:37:49 -0800
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-08 08:28:51 -0800
commitf0d1b0b30d250a07627ad8b9fbbb5c7cc08422e8 (patch)
tree0aa5379150574374351fb92af7881a48dbfcf2ce /mm
parent[PATCH] struct path: convert zorro (diff)
downloadlinux-dev-f0d1b0b30d250a07627ad8b9fbbb5c7cc08422e8.tar.xz
linux-dev-f0d1b0b30d250a07627ad8b9fbbb5c7cc08422e8.zip
[PATCH] LOG2: Implement a general integer log2 facility in the kernel
This facility provides three entry points: ilog2() Log base 2 of unsigned long ilog2_u32() Log base 2 of u32 ilog2_u64() Log base 2 of u64 These facilities can either be used inside functions on dynamic data: int do_something(long q) { ...; y = ilog2(x) ...; } Or can be used to statically initialise global variables with constant values: unsigned n = ilog2(27); When performing static initialisation, the compiler will report "error: initializer element is not constant" if asked to take a log of zero or of something not reducible to a constant. They treat negative numbers as unsigned. When not dealing with a constant, they fall back to using fls() which permits them to use arch-specific log calculation instructions - such as BSR on x86/x86_64 or SCAN on FRV - if available. [akpm@osdl.org: MMC fix] Signed-off-by: David Howells <dhowells@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: David Howells <dhowells@redhat.com> Cc: Wojtek Kaniewski <wojtekka@toxygen.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/page_alloc.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index cace22b3ac25..18f0e044c43d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3244,7 +3244,7 @@ void *__init alloc_large_system_hash(const char *tablename,
if (numentries > max)
numentries = max;
- log2qty = long_log2(numentries);
+ log2qty = ilog2(numentries);
do {
size = bucketsize << log2qty;
@@ -3266,7 +3266,7 @@ void *__init alloc_large_system_hash(const char *tablename,
printk("%s hash table entries: %d (order: %d, %lu bytes)\n",
tablename,
(1U << log2qty),
- long_log2(size) - PAGE_SHIFT,
+ ilog2(size) - PAGE_SHIFT,
size);
if (_hash_shift)