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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3D34CC77B75 for ; Wed, 24 May 2023 00:18:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238992AbjEXASA (ORCPT ); Tue, 23 May 2023 20:18:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40432 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236423AbjEXAR6 (ORCPT ); Tue, 23 May 2023 20:17:58 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 29837B5 for ; Tue, 23 May 2023 17:17:57 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B718D6376C for ; Wed, 24 May 2023 00:17:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C6650C433EF; Wed, 24 May 2023 00:17:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1684887476; bh=9dxLjHPo+SZEGy7KQS3cCv9yVec/7vFxtb4zBAqLmXg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Wr7T+5i/6DQrZylu3WCREvJ2bcO9dFx9j+flmANgbbKwhs3FVnYFrJV967oKEfeyD YaSfFfAdfwU/d4c/BDPMmayNOvc/FfiKVKHsE1Ay4B/b98MeOAAZv3MX7LVnwS1CfX Q88UbGhhrbK1+okbRb5/KhncQQ67FMZMShmeZgmhl3BrDuN0sWCn/FeDXxn5KnII0m wR8vT6zgg42KZZhLyDFnkwNsago373inq3hwEKApu1gWsnsEZlktQlfe8E3PuJm2Bd P3O3ZJLPpzsUU7TRBYQTyH8AJ9Py1nm/Hg426LOqE7Pb5CaeQ1hcY0ORJzf8MtqdLa 1YWM74O5ER+yA== Date: Wed, 24 May 2023 08:06:44 +0800 From: Jisheng Zhang To: Paul Walmsley , Palmer Dabbelt , Albert Ou Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Suren Baghdasaryan Subject: Re: [PATCH] riscv: mm: try VMA lock-based page fault handling first Message-ID: References: <20230523165942.2630-1-jszhang@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 24, 2023 at 01:11:55AM +0800, Jisheng Zhang wrote: > On Wed, May 24, 2023 at 12:59:42AM +0800, Jisheng Zhang wrote: > > Attempt VMA lock-based page fault handling first, and fall back to the > > existing mmap_lock-based handling if that fails. > > > > A simple running the ebizzy benchmark on Lichee Pi 4A shows that > > PER_VMA_LOCK can improve the ebizzy benchmark by about 32.68%. In > > theory, the more CPUs, the bigger improvement, but I don't have any > > HW platform which has more than 4 CPUs. > > > > This is the riscv variant of "x86/mm: try VMA lock-based page fault > > handling first". > > > > Signed-off-by: Jisheng Zhang > > --- > > Any performance numbers are welcome! Especially the numbers on HW > > platforms with 8 or more CPUs. > > PS: run ebizzy as below: > ./ebizzy -mTt your_nr_cpus Sorry, should be ./ebizzy -mTt 2*your_nr_cpus > > > > arch/riscv/Kconfig | 1 + > > arch/riscv/mm/fault.c | 33 +++++++++++++++++++++++++++++++++ > > 2 files changed, 34 insertions(+) > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > > index 62e84fee2cfd..b958f67f9a12 100644 > > --- a/arch/riscv/Kconfig > > +++ b/arch/riscv/Kconfig > > @@ -42,6 +42,7 @@ config RISCV > > select ARCH_SUPPORTS_DEBUG_PAGEALLOC if MMU > > select ARCH_SUPPORTS_HUGETLBFS if MMU > > select ARCH_SUPPORTS_PAGE_TABLE_CHECK if MMU > > + select ARCH_SUPPORTS_PER_VMA_LOCK if MMU > > select ARCH_USE_MEMTEST > > select ARCH_USE_QUEUED_RWLOCKS > > select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU > > diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c > > index 8685f85a7474..eccdddf26f4b 100644 > > --- a/arch/riscv/mm/fault.c > > +++ b/arch/riscv/mm/fault.c > > @@ -286,6 +286,36 @@ void handle_page_fault(struct pt_regs *regs) > > flags |= FAULT_FLAG_WRITE; > > else if (cause == EXC_INST_PAGE_FAULT) > > flags |= FAULT_FLAG_INSTRUCTION; > > +#ifdef CONFIG_PER_VMA_LOCK > > + if (!(flags & FAULT_FLAG_USER)) > > + goto lock_mmap; > > + > > + vma = lock_vma_under_rcu(mm, addr); > > + if (!vma) > > + goto lock_mmap; > > + > > + if (unlikely(access_error(cause, vma))) { > > + vma_end_read(vma); > > + goto lock_mmap; > > + } > > + > > + fault = handle_mm_fault(vma, addr, flags | FAULT_FLAG_VMA_LOCK, regs); > > + vma_end_read(vma); > > + > > + if (!(fault & VM_FAULT_RETRY)) { > > + count_vm_vma_lock_event(VMA_LOCK_SUCCESS); > > + goto done; > > + } > > + count_vm_vma_lock_event(VMA_LOCK_RETRY); > > + > > + if (fault_signal_pending(fault, regs)) { > > + if (!user_mode(regs)) > > + no_context(regs, addr); > > + return; > > + } > > +lock_mmap: > > +#endif /* CONFIG_PER_VMA_LOCK */ > > + > > retry: > > mmap_read_lock(mm); > > vma = find_vma(mm, addr); > > @@ -355,6 +385,9 @@ void handle_page_fault(struct pt_regs *regs) > > > > mmap_read_unlock(mm); > > > > +#ifdef CONFIG_PER_VMA_LOCK > > +done: > > +#endif > > if (unlikely(fault & VM_FAULT_ERROR)) { > > tsk->thread.bad_cause = cause; > > mm_fault_error(regs, addr, fault); > > -- > > 2.40.1 > > > > > > _______________________________________________ > > linux-riscv mailing list > > linux-riscv@lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-riscv