From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id C44E66B02C3 for ; Wed, 31 May 2017 12:31:41 -0400 (EDT) Received: by mail-wm0-f72.google.com with SMTP id b86so4006674wmi.6 for ; Wed, 31 May 2017 09:31:41 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id x105si15982290wrb.197.2017.05.31.09.31.40 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 31 May 2017 09:31:40 -0700 (PDT) Date: Wed, 31 May 2017 18:31:31 +0200 From: Michal Hocko Subject: Re: [v3 0/9] parallelized "struct page" zeroing Message-ID: <20170531163131.GY27783@dhcp22.suse.cz> References: <1494003796-748672-1-git-send-email-pasha.tatashin@oracle.com> <20170509181234.GA4397@dhcp22.suse.cz> <20170515193817.GC7551@dhcp22.suse.cz> <9b3d68aa-d2b6-2b02-4e75-f8372cbeb041@oracle.com> <20170516083601.GB2481@dhcp22.suse.cz> <07a6772b-711d-4fdc-f688-db76f1ec4c45@oracle.com> <20170529115358.GJ19725@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Pasha Tatashin Cc: linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, borntraeger@de.ibm.com, heiko.carstens@de.ibm.com, davem@davemloft.net On Tue 30-05-17 13:16:50, Pasha Tatashin wrote: > >Could you be more specific? E.g. how are other stores done in > >__init_single_page safe then? I am sorry to be dense here but how does > >the full 64B store differ from other stores done in the same function. > > Hi Michal, > > It is safe to do regular 8-byte and smaller stores (stx, st, sth, stb) > without membar, but they are slower compared to STBI which require a membar > before memory can be accessed. OK, so why cannot we make zero_struct_page 8x 8B stores, other arches would do memset. You said it would be slower but would that be measurable? I am sorry to be so persistent here but I would be really happier if this didn't depend on the deferred initialization. If this is absolutely a no-go then I can live with that of course. -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org