From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 599ABC433F5 for ; Thu, 2 Sep 2021 21:15:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4397F6108E for ; Thu, 2 Sep 2021 21:15:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347450AbhIBVQa (ORCPT ); Thu, 2 Sep 2021 17:16:30 -0400 Received: from mail.kernel.org ([198.145.29.99]:47180 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347511AbhIBVQ3 (ORCPT ); Thu, 2 Sep 2021 17:16:29 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A7A4660FDA; Thu, 2 Sep 2021 21:15:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1630617330; bh=BG5qgapEkLVW0Ox9ID/gZUtzivBIj8xYMKwJ0xaP9FQ=; h=Date:From:To:Subject:From; b=lKkcnaRPxu0YKdpxUOm4G3h6FUZHFsee+gYQ8aK2dXhgxkmCRZfEp2+nYWLcUfq0w vHlfSIcCpVDk3cmjPe7FF//cFFD8BO9cqU8GdDr1/fEj5aRCdAstUqI6ZA3+8ONlK8 bBl9NHdFvTmUmMMPIFgrXumwRPcgdWgNouAeSGQs= Date: Thu, 02 Sep 2021 14:15:30 -0700 From: akpm@linux-foundation.org To: anton@ozlabs.org, benh@kernel.crashing.org, luto@kernel.org, mm-commits@vger.kernel.org, npiggin@gmail.com, paulus@ozlabs.org, rdunlap@infradead.org Subject: [folded-merged] lazy-tlb-allow-lazy-tlb-mm-refcounting-to-be-configurable-fix-2.patch removed from -mm tree Message-ID: <20210902211530.P8saRTGC-%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: lazy-tlb-allow-lazy-tlb-mm-refcounting-to-be-configurable-fix-2 has been removed from the -mm tree. Its filename was lazy-tlb-allow-lazy-tlb-mm-refcounting-to-be-configurable-fix-2.patch This patch was dropped because it was folded into lazy-tlb-allow-lazy-tlb-mm-refcounting-to-be-configurable.patch ------------------------------------------------------ From: Nicholas Piggin Subject: lazy-tlb-allow-lazy-tlb-mm-refcounting-to-be-configurable-fix-2 Explain the requirements for lazy tlb mm refcounting in the comment, to help with archs that may want to disable this by some means other than MMU_LAZY_TLB_SHOOTDOWN. Link: https://lkml.kernel.org/r/1623121605.j47gdpccep.astroid@bobo.none Signed-off-by: Nicholas Piggin Cc: Anton Blanchard Cc: Andy Lutomirski Cc: Randy Dunlap Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Signed-off-by: Andrew Morton --- arch/Kconfig | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/arch/Kconfig~lazy-tlb-allow-lazy-tlb-mm-refcounting-to-be-configurable-fix-2 +++ a/arch/Kconfig @@ -426,6 +426,16 @@ config ARCH_WANT_IRQS_OFF_ACTIVATE_MM shootdowns should enable this. # Use normal mm refcounting for MMU_LAZY_TLB kernel thread references. +# MMU_LAZY_TLB_REFCOUNT=n can improve the scalability of context switching +# to/from kernel threads when the same mm is running on a lot of CPUs (a large +# multi-threaded application), by reducing contention on the mm refcount. +# +# This can be disabled if the architecture ensures no CPUs are using an mm as a +# "lazy tlb" beyond its final refcount (i.e., by the time __mmdrop frees the mm +# or its kernel page tables). This could be arranged by arch_exit_mmap(), or +# final exit(2) TLB flush, for example. arch code must also ensure the +# _lazy_tlb variants of mmgrab/mmdrop are used when dropping the lazy reference +# to a kthread ->active_mm (non-arch code has been converted already). config MMU_LAZY_TLB_REFCOUNT def_bool y _ Patches currently in -mm which might be from npiggin@gmail.com are lazy-tlb-introduce-lazy-mm-refcount-helper-functions.patch lazy-tlb-allow-lazy-tlb-mm-refcounting-to-be-configurable.patch lazy-tlb-shoot-lazies-a-non-refcounting-lazy-tlb-option.patch lazy-tlb-shoot-lazies-a-non-refcounting-lazy-tlb-option-fix.patch powerpc-64s-enable-mmu_lazy_tlb_shootdown.patch fs-epoll-use-a-per-cpu-counter-for-users-watches-count.patch