From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx146.postini.com [74.125.245.146]) by kanga.kvack.org (Postfix) with SMTP id 1CC6E6B0031 for ; Thu, 8 Aug 2013 20:11:52 -0400 (EDT) Received: by mail-ve0-f174.google.com with SMTP id d10so3544196vea.5 for ; Thu, 08 Aug 2013 17:11:51 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <20130807134058.GC12843@quack.suse.cz> <520286A4.1020101@intel.com> <20130808101807.GB4325@quack.suse.cz> <20130808185340.GA13926@quack.suse.cz> From: Andy Lutomirski Date: Thu, 8 Aug 2013 17:11:30 -0700 Message-ID: Subject: Re: [RFC 0/3] Add madvise(..., MADV_WILLWRITE) Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Jan Kara Cc: Dave Hansen , linux-mm@kvack.org, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org On Thu, Aug 8, 2013 at 12:25 PM, Andy Lutomirski wrote: > > Whoops -- I read your email too quickly. I haven't tried > MADV_WILLNEED, but I think I tried reading each page to fault them in. > Is there any reason to expect MADV_WILLNEED to do any better? I'll > try to do some new tests to see how well this all works. > > (I imagine that freshly fallocated files are somehow different when > read, since there aren't zeros on the disk backing them until they get > written.) Well, this will teach me to write code based on an old benchmark from memory. It seems that prefaulting for read is okay on Linux 3.9 -- latencytop isn't do_wp_page or ext4* at all, at least not for the last couple minutes on my test box. I wonder if ext4 changed its handling of fallocated extents somewhere between 3.5 and 3.9. In any case, please consider these patches withdrawn for the time being. * With file_update_time stubbed out. I need to dust off my old patches to fix that part. -- 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