From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-x236.google.com (mail-pl0-x236.google.com [IPv6:2607:f8b0:400e:c01::236]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 40QgJS40nLzF1pY for ; Wed, 18 Apr 2018 08:43:20 +1000 (AEST) Received: by mail-pl0-x236.google.com with SMTP id m7-v6so1240307plt.3 for ; Tue, 17 Apr 2018 15:43:20 -0700 (PDT) Date: Wed, 18 Apr 2018 08:43:07 +1000 From: Balbir Singh To: "Aneesh Kumar K.V" Cc: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH V1 00/11] powerpc/mm/book3s64: Support for split pmd ptlock Message-ID: <20180418084308.79e28ede@gmail.com> In-Reply-To: <20180416112724.9677-1-aneesh.kumar@linux.ibm.com> References: <20180416112724.9677-1-aneesh.kumar@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, 16 Apr 2018 16:57:12 +0530 "Aneesh Kumar K.V" wrote: > This patch series add split pmd pagetable lock for book3s64. nohash64 also should > be able to switch to this. I need to workout the code dependency. This series > also migh have broken the build on platforms otherthan book3s64. I am sending this early > to get feedback on whether we should continue with the approach. > > We switch the pmd allocator to use something similar to what we already use for > level 4 pagetable allocation. We get an order 0 page and divide that to fragments > and hand over fragments when we get request for a pmd pagetable. The pmd lock is > now stashed in the struct page backing the allocated page. That's only for the THP case right? > > The series helps in reducing lock contention on mm->page_table_lock. > The numbers look good.