Commit 5333a3de authored Aug 19, 2010 by Phil Carmody Committed by Russell King Sep 02, 2010

ARM: 6341/1: unwind - optimise linked-list searches for modules



With several sections per module, and dozens of modules, the
searches down the linked list of sections would dominate the
lookup time, dwarfing any savings from the binary search
within the section.

A simple move-to-front optimisation exploits the commonality
of the code paths taken, and in simple real-world tests reduces
the number of steps in the search to barely more than 1.

Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

parent 09e56a2d

arch/arm/kernel/unwind.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -146,6 +146,8 @@ static struct unwind_idx *unwind_find_idx(unsigned long addr)
		addr < table->end_addr) {
		idx = search_index(addr, table->start,
		table->stop - 1);
		/* Move-to-front to exploit common traces */
		list_move(&table->list, &unwind_tables);
		break;
		}
		}

Admin message