[PATCH 2/2] zsmalloc: micro-optimize zs_object_copy()
From: Sergey Senozhatsky <hidden>
Date: 2015-03-24 15:24:45
Also in:
lkml
Subsystem:
memory management, the rest, zsmalloc compressed slab memory allocator · Maintainers:
Andrew Morton, Linus Torvalds, Minchan Kim, Sergey Senozhatsky
A micro-optimization. Avoid additional branching and reduce (a bit) registry pressure (f.e. s_off += size; d_off += size; may be calculated twise: first for >= PAGE_SIZE check and later for offset update in "else" clause). /scripts/bloat-o-meter shows some improvement add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-10 (-10) function old new delta zs_object_copy 550 540 -10 Signed-off-by: Sergey Senozhatsky <redacted> --- mm/zsmalloc.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 7af4456..dc35328 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c@@ -1535,28 +1535,27 @@ static void zs_object_copy(unsigned long src, unsigned long dst, if (written == class->size) break; - if (s_off + size >= PAGE_SIZE) { + s_off += size; + s_size -= size; + d_off += size; + d_size -= size; + + if (s_off >= PAGE_SIZE) { kunmap_atomic(s_addr); s_page = get_next_page(s_page); BUG_ON(!s_page); s_addr = kmap_atomic(s_page); s_size = class->size - written; s_off = 0; - } else { - s_off += size; - s_size -= size; } - if (d_off + size >= PAGE_SIZE) { + if (d_off >= PAGE_SIZE) { kunmap_atomic(d_addr); d_page = get_next_page(d_page); BUG_ON(!d_page); d_addr = kmap_atomic(d_page); d_size = class->size - written; d_off = 0; - } else { - d_off += size; - d_size -= size; } }
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2.3.4
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