Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Yair Podemsky <ypodemsk@redhat.com>
To:     mtosatti@redhat.com, ppandit@redhat.com, david@redhat.com,
        linux@armlinux.org.uk, mpe@ellerman.id.au, npiggin@gmail.com,
        christophe.leroy@csgroup.eu, hca@linux.ibm.com, gor@linux.ibm.com,
        agordeev@linux.ibm.com, borntraeger@linux.ibm.com,
        svens@linux.ibm.com, davem@davemloft.net, tglx@linutronix.de,
        mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
        hpa@zytor.com, keescook@chromium.org, paulmck@kernel.org,
        frederic@kernel.org, will@kernel.org, peterz@infradead.org,
        ardb@kernel.org, samitolvanen@google.com,
        juerg.haefliger@canonical.com, arnd@arndb.de,
        rmk+kernel@armlinux.org.uk, geert+renesas@glider.be,
        linus.walleij@linaro.org, akpm@linux-foundation.org,
        sebastian.reichel@collabora.com, rppt@kernel.org,
        aneesh.kumar@linux.ibm.com, x86@kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
        sparclinux@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc:     ypodemsk@redhat.com
Subject: [PATCH v2 0/2] send tlb_remove_table_smp_sync IPI only to necessary CPUs
Date:   Tue, 20 Jun 2023 17:46:16 +0300
Message-Id: <20230620144618.125703-1-ypodemsk@redhat.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Currently the tlb_remove_table_smp_sync IPI is sent to all CPUs
indiscriminately, this causes unnecessary work and delays notable in
real-time use-cases and isolated cpus.
By limiting the IPI to only be sent to cpus referencing the effected
mm.
a config to differentiate architectures that support mm_cpumask from
those that don't will allow safe usage of this feature.

changes from -v1:
- Previous version included a patch to only send the IPI to CPU's with
context_tracking in the kernel space, this was removed due to race 
condition concerns.
- for archs that do not maintain mm_cpumask the mask used should be
 cpu_online_mask (Peter Zijlstra).
 
 v1: https://lore.kernel.org/all/20230404134224.137038-1-ypodemsk@redhat.com/

Yair Podemsky (2):
  arch: Introduce ARCH_HAS_CPUMASK_BITS
  mm/mmu_gather: send tlb_remove_table_smp_sync IPI only to MM CPUs

 arch/Kconfig              |  8 ++++++++
 arch/arm/Kconfig          |  1 +
 arch/powerpc/Kconfig      |  1 +
 arch/s390/Kconfig         |  1 +
 arch/sparc/Kconfig        |  1 +
 arch/x86/Kconfig          |  1 +
 include/asm-generic/tlb.h |  4 ++--
 mm/khugepaged.c           |  4 ++--
 mm/mmu_gather.c           | 17 ++++++++++++-----
 9 files changed, 29 insertions(+), 9 deletions(-)

-- 
2.39.3