From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Sat, 16 May 2015 00:42:03 +0200 (CEST) Received: from mailapp01.imgtec.com ([195.59.15.196]:61411 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S27012643AbbEOWmBa4XVi (ORCPT ); Sat, 16 May 2015 00:42:01 +0200 Received: from KLMAIL01.kl.imgtec.org (unknown [192.168.5.35]) by Websense Email Security Gateway with ESMTPS id 5B98442885CC7; Fri, 15 May 2015 23:41:54 +0100 (IST) Received: from hhmail02.hh.imgtec.org (10.100.10.20) by KLMAIL01.kl.imgtec.org (192.168.5.35) with Microsoft SMTP Server (TLS) id 14.3.195.1; Fri, 15 May 2015 23:39:57 +0100 Received: from BAMAIL02.ba.imgtec.org (10.20.40.28) by hhmail02.hh.imgtec.org (10.100.10.20) with Microsoft SMTP Server (TLS) id 14.3.224.2; Fri, 15 May 2015 23:39:56 +0100 Received: from [10.20.3.79] (10.20.3.79) by bamail02.ba.imgtec.org (10.20.40.28) with Microsoft SMTP Server (TLS) id 14.3.174.1; Fri, 15 May 2015 15:39:54 -0700 Message-ID: <555675BA.9000700@imgtec.com> Date: Fri, 15 May 2015 15:39:54 -0700 From: Leonid Yegoshin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Ralf Baechle CC: , , , , , , , , , , Subject: Re: [PATCH v2] MIPS64: Support of at least 48 bits of SEGBITS References: <20150515013351.7450.12130.stgit@ubuntu-yegoshin> <20150515215320.GI2322@linux-mips.org> In-Reply-To: <20150515215320.GI2322@linux-mips.org> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.20.3.79] Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 47425 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: Leonid.Yegoshin@imgtec.com Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips On 05/15/2015 02:53 PM, Ralf Baechle wrote: > On Thu, May 14, 2015 at 06:34:43PM -0700, Leonid Yegoshin wrote: > > The order 1 allocation for the PGD are concerning me a little. On a > system under even moderate memory pressure that might become a bit of > a reliability or performance issue. > > With 4kB pages we already need order 1 or even 2 allocations for the > allocation of the stack and some folks have reported that to be an issue > so we may have to start using the PUD for very large VA spaces. > > Ralf I don't think it is an issue here - people, who wants to exercise 256 TERABAIT of memory PER PROCESS may even doesn't note that they have PGD = 2 pages. It is definitely not for systems with 4GB physmemory. I also recommend for low memory to look into CONFIG_COMPACTION, it may be a great help for them here, look into mm/vmscan.c, in_reclaim_compaction(). Besides that, I defined this feature for 16KB and 64KB pages only, not for 4KB. From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailapp01.imgtec.com ([195.59.15.196]:61411 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S27012643AbbEOWmBa4XVi (ORCPT ); Sat, 16 May 2015 00:42:01 +0200 Message-ID: <555675BA.9000700@imgtec.com> Date: Fri, 15 May 2015 15:39:54 -0700 From: Leonid Yegoshin MIME-Version: 1.0 Subject: Re: [PATCH v2] MIPS64: Support of at least 48 bits of SEGBITS References: <20150515013351.7450.12130.stgit@ubuntu-yegoshin> <20150515215320.GI2322@linux-mips.org> In-Reply-To: <20150515215320.GI2322@linux-mips.org> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-Path: Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-subscribe: List-owner: List-post: List-archive: To: Ralf Baechle Cc: aleksey.makarov@auriga.com, james.hogan@imgtec.com, paul.burton@imgtec.com, david.daney@cavium.com, peterz@infradead.org, linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, davidlohr@hp.com, kirill@shutemov.name, akpm@linux-foundation.org, mingo@kernel.org Message-ID: <20150515223954.RuiAdbVtuu9yZFg7RvnbGdAxiiz1Pl3RICKFKpQpX04@z> On 05/15/2015 02:53 PM, Ralf Baechle wrote: > On Thu, May 14, 2015 at 06:34:43PM -0700, Leonid Yegoshin wrote: > > The order 1 allocation for the PGD are concerning me a little. On a > system under even moderate memory pressure that might become a bit of > a reliability or performance issue. > > With 4kB pages we already need order 1 or even 2 allocations for the > allocation of the stack and some folks have reported that to be an issue > so we may have to start using the PUD for very large VA spaces. > > Ralf I don't think it is an issue here - people, who wants to exercise 256 TERABAIT of memory PER PROCESS may even doesn't note that they have PGD = 2 pages. It is definitely not for systems with 4GB physmemory. I also recommend for low memory to look into CONFIG_COMPACTION, it may be a great help for them here, look into mm/vmscan.c, in_reclaim_compaction(). Besides that, I defined this feature for 16KB and 64KB pages only, not for 4KB.