Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S941814AbcLVXEu (ORCPT ); Thu, 22 Dec 2016 18:04:50 -0500 Received: from mail-vk0-f67.google.com ([209.85.213.67]:35068 "EHLO mail-vk0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S941796AbcLVXEt (ORCPT ); Thu, 22 Dec 2016 18:04:49 -0500 MIME-Version: 1.0 In-Reply-To: References: <20161126201534.5d5e338f678b478e7a7b8dc3@gmail.com> <20161129143916.f24c141c1a264bad1220031e@linux-foundation.org> From: Vitaly Wool Date: Fri, 23 Dec 2016 00:04:47 +0100 Message-ID: Subject: Re: [PATCH 0/2] z3fold fixes To: Dan Streetman Cc: Andrew Morton , Linux-MM , linux-kernel , Arnd Bergmann , Dan Carpenter Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id uBMN4tk2009167 Content-Length: 4191 Lines: 89 On Thu, Dec 22, 2016 at 10:55 PM, Dan Streetman wrote: > On Sun, Dec 18, 2016 at 3:15 AM, Vitaly Wool wrote: >> On Tue, Nov 29, 2016 at 11:39 PM, Andrew Morton >> wrote: >>> On Tue, 29 Nov 2016 17:33:19 -0500 Dan Streetman wrote: >>> >>>> On Sat, Nov 26, 2016 at 2:15 PM, Vitaly Wool wrote: >>>> > Here come 2 patches with z3fold fixes for chunks counting and locking. As commit 50a50d2 ("z3fold: don't fail kernel build is z3fold_header is too big") was NAK'ed [1], I would suggest that we removed that one and the next z3fold commit cc1e9c8 ("z3fold: discourage use of pages that weren't compacted") and applied the coming 2 instead. >>>> >>>> Instead of adding these onto all the previous ones, could you redo the >>>> entire z3fold series? I think it'll be simpler to review the series >>>> all at once and that would remove some of the stuff from previous >>>> patches that shouldn't be there. >>>> >>>> If that's ok with Andrew, of course, but I don't think any of the >>>> z3fold patches have been pushed to Linus yet. >>> >>> Sounds good to me. I had a few surprise rejects when merging these >>> two, which indicates that things might be out of sync. >>> >>> I presently have: >>> >>> z3fold-limit-first_num-to-the-actual-range-of-possible-buddy-indexes.patch >>> z3fold-make-pages_nr-atomic.patch >>> z3fold-extend-compaction-function.patch >>> z3fold-use-per-page-spinlock.patch >>> z3fold-discourage-use-of-pages-that-werent-compacted.patch >>> z3fold-fix-header-size-related-issues.patch >>> z3fold-fix-locking-issues.patch >> >> My initial suggestion was to have it the following way: >> z3fold-limit-first_num-to-the-actual-range-of-possible-buddy-indexes.patch > > this is a good one, acked by both of us; it should stay and go upstream to Linus > >> z3fold-make-pages_nr-atomic.patch > > the change itself looks ok and I acked it, but as Andrew commented the > log says nothing about why it's being changed; the atomic function is > slower so the log should explain why it's being changed; anyone > reviewing the log history won't know why you made the change, and the > change all by itself is a step backwards in performance. > >> z3fold-extend-compaction-function.patch > > this explictly has a bug in it that's fixed in one of the later > patches; instead, this should be fixed up and resent. > >> z3fold-use-per-page-spinlock.patch > > i should have explicitly nak'ed this, as not only did it add a bug > (fixed by the the other 'fix-' patch below) but its design should be > replaced by kref counting, which your latest patch is working > towards... > >> z3fold-fix-header-size-related-issues.patch >> z3fold-fix-locking-issues.patch > > and these fix the known problems in the previous patches. > >> >> I would prefer to keep the fix-XXX patches separate since e. g. >> z3fold-fix-header-size-related-issues.patch concerns also the problems >> that have been in the code for a while now. I am ok with folding these >> into the relevant main patches but once again, given that some fixes >> are related to the code that is already merged, I don't see why it >> would be better. > > none of those patches are "merged", the last z3fold patch in Linus' > tree is 43afc194 from June. Just because they're in Andrew's mmotm > queue (and/or linux-next) doesn't mean they are going to be > merged...(correct me please if I'm wrong there Andrew) that I do understand, however, z3fold-fix-header-size-related-issues.patch fixes the off-by-one issue present in the code that is in Linus's tree too. > So as you can see by my patch-by-patch breakdown, almost all of them > need changes based on feedback from various people. And they are all > related - your goal is to improve z3fold performance, right? IMHO > they should be sent as a single patch series with that goal in the > cover letter, including specific details and numbers about how the > series does improve performance. but that is a good idea anyway, the only thing i\m not sure about is whether it makes sense to fold z3fold-fix-header-size-related-issues.patch into another or not. ~vitaly