From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-x231.google.com (mail-pb0-x231.google.com [IPv6:2607:f8b0:400e:c01::231]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 361311400DD for ; Fri, 16 May 2014 03:29:38 +1000 (EST) Received: by mail-pb0-f49.google.com with SMTP id jt11so1364488pbb.22 for ; Thu, 15 May 2014 10:29:34 -0700 (PDT) Date: Thu, 15 May 2014 10:28:17 -0700 (PDT) From: Hugh Dickins To: Madhavan Srinivasan Subject: Re: [PATCH V4 0/2] mm: FAULT_AROUND_ORDER patchset performance data for powerpc In-Reply-To: <537479E7.90806@linux.vnet.ibm.com> Message-ID: References: <1399541296-18810-1-git-send-email-maddy@linux.vnet.ibm.com> <537479E7.90806@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: linux-arch@vger.kernel.org, riel@redhat.com, rusty@rustcorp.com.au, dave.hansen@intel.com, peterz@infradead.org, x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ak@linux.intel.com, paulus@samba.org, mgorman@suse.de, akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org, mingo@kernel.org, kirill.shutemov@linux.intel.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 15 May 2014, Madhavan Srinivasan wrote: > > Hi Ingo, > > Do you have any comments for the latest version of the patchset. If > not, kindly can you pick it up as is. > > > With regards > Maddy > > > Kirill A. Shutemov with 8c6e50b029 commit introduced > > vm_ops->map_pages() for mapping easy accessible pages around > > fault address in hope to reduce number of minor page faults. > > > > This patch creates infrastructure to modify the FAULT_AROUND_ORDER > > value using mm/Kconfig. This will enable architecture maintainers > > to decide on suitable FAULT_AROUND_ORDER value based on > > performance data for that architecture. First patch also defaults > > FAULT_AROUND_ORDER Kconfig element to 4. Second patch list > > out the performance numbers for powerpc (platform pseries) and > > initialize the fault around order variable for pseries platform of > > powerpc. Sorry for not commenting earlier - just reminded by this ping to Ingo. I didn't study your numbers, but nowhere did I see what PAGE_SIZE you use. arch/powerpc/Kconfig suggests that Power supports base page size of 4k, 16k, 64k or 256k. I would expect your optimal fault_around_order to depend very much on the base page size. Perhaps fault_around_size would provide a more useful default? Hugh