zsmalloc: micro-optimize zs_object_copy()
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 <sergey.senozhatsky@gmail.com> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Nitin Gupta <ngupta@vflare.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -1537,7 +1537,12 @@ static void zs_object_copy(unsigned long src, unsigned long dst,
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if (written == class->size)
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break;
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if (s_off + size >= PAGE_SIZE) {
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s_off += size;
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s_size -= size;
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d_off += size;
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d_size -= size;
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if (s_off >= PAGE_SIZE) {
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kunmap_atomic(d_addr);
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kunmap_atomic(s_addr);
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s_page = get_next_page(s_page);
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@ -1546,21 +1551,15 @@ static void zs_object_copy(unsigned long src, unsigned long dst,
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d_addr = kmap_atomic(d_page);
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s_size = class->size - written;
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s_off = 0;
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} else {
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s_off += size;
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s_size -= size;
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}
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if (d_off + size >= PAGE_SIZE) {
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if (d_off >= PAGE_SIZE) {
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kunmap_atomic(d_addr);
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d_page = get_next_page(d_page);
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BUG_ON(!d_page);
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d_addr = kmap_atomic(d_page);
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d_size = class->size - written;
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d_off = 0;
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} else {
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d_off += size;
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d_size -= size;
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}
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}
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