From bdcb1aefc5b3f7d0f1dc8b02673602bca2ff7a4b Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Wed, 17 Jan 2018 23:58:18 +1000 Subject: powerpc/64s: Improve RFI L1-D cache flush fallback The fallback RFI flush is used when firmware does not provide a way to flush the cache. It's a "displacement flush" that evicts useful data by displacing it with an uninteresting buffer. The flush has to take care to work with implementation specific cache replacment policies, so the recipe has been in flux. The initial slow but conservative approach is to touch all lines of a congruence class, with dependencies between each load. It has since been determined that a linear pattern of loads without dependencies is sufficient, and is significantly faster. Measuring the speed of a null syscall with RFI fallback flush enabled gives the relative improvement: P8 - 1.83x P9 - 1.75x The flush also becomes simpler and more adaptable to different cache geometries. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman --- arch/powerpc/xmon/xmon.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'arch/powerpc/xmon') diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c index 01d9a2dcff20..82e1a3ee6e0f 100644 --- a/arch/powerpc/xmon/xmon.c +++ b/arch/powerpc/xmon/xmon.c @@ -2377,8 +2377,6 @@ static void dump_one_paca(int cpu) printf(" slb_cache[%d]: = 0x%016lx\n", i, p->slb_cache[i]); DUMP(p, rfi_flush_fallback_area, "px"); - DUMP(p, l1d_flush_congruence, "llx"); - DUMP(p, l1d_flush_sets, "llx"); #endif DUMP(p, dscr_default, "llx"); #ifdef CONFIG_PPC_BOOK3E -- cgit v1.2.3