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Commit e8de85ca authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/mm: Only call store_updates_sp() on stores in do_page_fault() 



Function store_updates_sp() checks whether the faulting
instruction is a store updating r1. Therefore we can limit its calls
to store exceptions.

This patch is an improvement of commit a7a9dcd8 ("powerpc: Avoid
taking a data miss on every userspace instruction miss")

With the same microbenchmark app, run with 500 as argument, on an
MPC885 we get:

Before this patch: 152000 DTLB misses
After this patch:  147000 DTLB misses

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 9affa9e2

arch/powerpc/mm/fault.c

+1 −1
Original line number Diff line number Diff line
@@ -287,7 +287,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address, 
	 * can result in fault, which will cause a deadlock when called with

	 * mmap_sem held

	 */

	if (!is_exec && user_mode(regs))

	if (is_write && user_mode(regs))

		store_update_sp = store_updates_sp(regs);



	if (user_mode(regs))