linux-kernel - [PATCH v5 4/4] powerpc/64s: enable MMU_LAZY_TLB

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-Id: <20211109041119.1972927-5-npiggin@gmail.com>
Date:   Tue,  9 Nov 2021 14:11:19 +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>,
        Andy Lutomirski <luto@...nel.org>, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v5 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, due to contention on the mm refcount.

powerpc/64s meets the prerequisites for CONFIG_MMU_LAZY_TLB_SHOOTDOWN,
so enable the option. This increases the above benchmark 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 ba5b66189358..8a584414ef67 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -249,6 +249,7 @@ 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