linux-kernel - [PATCH v4 4/4] powerpc/64s: enable MMU_LAZY_TLB

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Message-Id: <20210605014216.446867-5-npiggin@gmail.com>
Date:   Sat,  5 Jun 2021 11:42:16 +1000
From:   Nicholas Piggin <npiggin@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Nicholas Piggin <npiggin@...il.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-mm@...ck.org,
        Anton Blanchard <anton@...abs.org>,
        Andy Lutomirski <luto@...nel.org>
Subject: [PATCH v4 4/4] powerpc/64s: enable MMU_LAZY_TLB_SHOOTDOWN

On a 16-socket 192-core POWER8 system, a context switching benchmark
with as many software threads as CPUs (so each switch will go in and
out of idle), upstream can achieve a rate of about 1 million context
switches per second. After this patch it goes up to 118 million.

Signed-off-by: Nicholas Piggin <npiggin@...il.com>
---
 arch/powerpc/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 088dd2afcfe4..8a092eedc692 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -252,6 +252,7 @@ config PPC
 	select IRQ_FORCED_THREADING
 	select MMU_GATHER_PAGE_SIZE
 	select MMU_GATHER_RCU_TABLE_FREE
+	select MMU_LAZY_TLB_SHOOTDOWN		if PPC_BOOK3S_64
 	select MODULES_USE_ELF_RELA
 	select NEED_DMA_MAP_STATE		if PPC64 || NOT_COHERENT_CACHE
 	select NEED_SG_DMA_LENGTH
-- 
2.23.0