Return-Path: Received: from mail-qt0-f174.google.com ([209.85.216.174]:35363 "EHLO mail-qt0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750707AbdAXRXO (ORCPT ); Tue, 24 Jan 2017 12:23:14 -0500 Received: by mail-qt0-f174.google.com with SMTP id x49so192993490qtc.2 for ; Tue, 24 Jan 2017 09:23:14 -0800 (PST) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 10.2 \(3259\)) Subject: Re: regression in DIO write behavior From: Weston Andros Adamson In-Reply-To: <1485272659.3143.18.camel@redhat.com> Date: Tue, 24 Jan 2017 12:23:12 -0500 Cc: linux-nfs list Message-Id: <963DBD29-C835-4716-9EAE-74C2EACA427F@monkey.org> References: <1485272659.3143.18.camel@redhat.com> To: Jeffrey Layton Sender: linux-nfs-owner@vger.kernel.org List-ID: Hey Jeff, That sounds like a regression to me. I don't think it's been around since the pgio rework, but maybe? -dros > On Jan 24, 2017, at 10:44 AM, Jeff Layton wrote: > > I've noticed a probable regression in recent kernels. When you run the > attached program on an older kernel (I used 2.6.32-642.6.2.el6.x86_64), > I see the kernel generate wsize WRITE calls on the wire. > > When I run the same program on a more modern kernel (mainline as of > today), it generates a ton of page-sized I/Os instead. I've verified > that iov_iter_get_pages_alloc is returning a wsize array of pages, it > just seems like the request handling code isn't stitching them together > like it should. > > Is this an expected change or a regression? I'm guessing the latter, and > that it might have crept in during the pageio rework from a couple of > years ago. > > Any idea where the bug might be? > -- > Jeff Layton