From: Nicholas Piggin <npiggin@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Nicholas Piggin <npiggin@gmail.com>,
Andy Lutomirski <luto@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-arch <linux-arch@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v6 4/5] powerpc/64s: enable MMU_LAZY_TLB_SHOOTDOWN
Date: Wed, 18 Jan 2023 18:00:10 +1000 [thread overview]
Message-ID: <20230118080011.2258375-5-npiggin@gmail.com> (raw)
In-Reply-To: <20230118080011.2258375-1-npiggin@gmail.com>
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.
64s meets the prerequisites for CONFIG_MMU_LAZY_TLB_SHOOTDOWN, so enable
the option. This increases the above benchmark to 118 million context
switches per second.
This generates 314 additional IPI interrupts on a 144 CPU system doing
a kernel compile, which is in the noise in terms of kernel cycles.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/Kconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index b8c4ac56bddc..600ace5a7f1a 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -265,6 +265,7 @@ config PPC
select MMU_GATHER_PAGE_SIZE
select MMU_GATHER_RCU_TABLE_FREE
select MMU_GATHER_MERGE_VMAS
+ 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_PER_CPU_EMBED_FIRST_CHUNK if PPC64
--
2.37.2
WARNING: multiple messages have this Message-ID (diff)
From: Nicholas Piggin <npiggin@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-arch <linux-arch@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Nicholas Piggin <npiggin@gmail.com>,
linux-mm <linux-mm@kvack.org>, Andy Lutomirski <luto@kernel.org>,
linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v6 4/5] powerpc/64s: enable MMU_LAZY_TLB_SHOOTDOWN
Date: Wed, 18 Jan 2023 18:00:10 +1000 [thread overview]
Message-ID: <20230118080011.2258375-5-npiggin@gmail.com> (raw)
In-Reply-To: <20230118080011.2258375-1-npiggin@gmail.com>
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.
64s meets the prerequisites for CONFIG_MMU_LAZY_TLB_SHOOTDOWN, so enable
the option. This increases the above benchmark to 118 million context
switches per second.
This generates 314 additional IPI interrupts on a 144 CPU system doing
a kernel compile, which is in the noise in terms of kernel cycles.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/Kconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index b8c4ac56bddc..600ace5a7f1a 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -265,6 +265,7 @@ config PPC
select MMU_GATHER_PAGE_SIZE
select MMU_GATHER_RCU_TABLE_FREE
select MMU_GATHER_MERGE_VMAS
+ 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_PER_CPU_EMBED_FIRST_CHUNK if PPC64
--
2.37.2
next prev parent reply other threads:[~2023-01-18 8:47 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-18 8:00 [PATCH v6 0/5] shoot lazy tlbs Nicholas Piggin
2023-01-18 8:00 ` Nicholas Piggin
2023-01-18 8:00 ` [PATCH v6 1/5] lazy tlb: introduce lazy tlb mm refcount helper functions Nicholas Piggin
2023-01-18 8:00 ` Nicholas Piggin
2023-01-18 8:00 ` [PATCH v6 2/5] lazy tlb: allow lazy tlb mm refcounting to be configurable Nicholas Piggin
2023-01-18 8:00 ` Nicholas Piggin
2023-01-23 7:35 ` Nadav Amit
2023-01-23 7:35 ` Nadav Amit
2023-01-23 8:02 ` Nadav Amit
2023-01-23 8:02 ` Nadav Amit
2023-01-24 2:29 ` Nicholas Piggin
2023-01-24 2:29 ` Nicholas Piggin
2023-01-18 8:00 ` [PATCH v6 3/5] lazy tlb: shoot lazies, non-refcounting lazy tlb mm reference handling scheme Nicholas Piggin
2023-01-18 8:00 ` Nicholas Piggin
2023-01-18 22:22 ` Nadav Amit
2023-01-18 22:22 ` Nadav Amit
2023-01-19 0:53 ` Nicholas Piggin
2023-01-19 0:53 ` Nicholas Piggin
2023-01-19 4:22 ` Nicholas Piggin
2023-01-19 4:22 ` Nicholas Piggin
2023-01-23 8:16 ` Nadav Amit
2023-01-23 8:16 ` Nadav Amit
2023-01-24 3:16 ` Nicholas Piggin
2023-01-24 3:16 ` Nicholas Piggin
2023-01-18 8:00 ` Nicholas Piggin [this message]
2023-01-18 8:00 ` [PATCH v6 4/5] powerpc/64s: enable MMU_LAZY_TLB_SHOOTDOWN Nicholas Piggin
2023-01-18 17:30 ` Linus Torvalds
2023-01-18 17:30 ` Linus Torvalds
2023-01-19 3:04 ` Nicholas Piggin
2023-01-19 3:04 ` Nicholas Piggin
2023-01-18 8:00 ` [PATCH v6 5/5] powerpc/64s/radix: combine final TLB flush and lazy tlb mm shootdown IPIs Nicholas Piggin
2023-01-18 8:00 ` Nicholas Piggin
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