From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f41.google.com (mail-qg0-f41.google.com [209.85.192.41]) by kanga.kvack.org (Postfix) with ESMTP id 11A146B0254 for ; Thu, 25 Feb 2016 14:11:54 -0500 (EST) Received: by mail-qg0-f41.google.com with SMTP id b67so47784263qgb.1 for ; Thu, 25 Feb 2016 11:11:54 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id g131si9320857qkb.102.2016.02.25.11.11.53 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 25 Feb 2016 11:11:53 -0800 (PST) From: Jeff Moyer Subject: Re: [RFC 0/2] New MAP_PMEM_AWARE mmap flag References: <20160223095225.GB32294@infradead.org> <56CC686A.9040909@plexistor.com> <56CCD54C.3010600@plexistor.com> <20160224225623.GL14668@dastard> Date: Thu, 25 Feb 2016 14:11:49 -0500 In-Reply-To: (Jeff Moyer's message of "Thu, 25 Feb 2016 11:24:57 -0500") Message-ID: MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: Dave Chinner Cc: Arnd Bergmann , linux-nvdimm , Oleg Nesterov , Christoph Hellwig , linux-mm , Mel Gorman , Johannes Weiner , "Kirill A. Shutemov" Jeff Moyer writes: >> The big issue we have right now is that we haven't made the DAX/pmem >> infrastructure work correctly and reliably for general use. Hence >> adding new APIs to workaround cases where we haven't yet provided >> correct behaviour, let alone optimised for performance is, quite >> frankly, a clear case premature optimisation. > > Again, I see the two things as separate issues. You need both. > Implementing MAP_SYNC doesn't mean we don't have to solve the bigger > issue of making existing applications work safely. I want to add one more thing to this discussion, just for the sake of clarity. When I talk about existing applications and pmem, I mean applications that already know how to detect and recover from torn sectors. Any application that assumes hardware does not tear sectors should be run on a file system layered on top of the btt. I think this underlying assumption may have been overlooked in this discussion, and could very well be a source of confusion. Cheers, Jeff -- 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