Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1753194AbdLSOFS (ORCPT <rfc822;w@1wt.eu>);
        Tue, 19 Dec 2017 09:05:18 -0500
Received: from www262.sakura.ne.jp ([202.181.97.72]:14596 "EHLO
        www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1751042AbdLSOFO (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 19 Dec 2017 09:05:14 -0500
To: wei.w.wang@intel.com
Cc: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org,
        qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org,
        kvm@vger.kernel.org, linux-mm@kvack.org, mst@redhat.com,
        mhocko@kernel.org, akpm@linux-foundation.org, mawilcox@microsoft.com,
        david@redhat.com, cornelia.huck@de.ibm.com,
        mgorman@techsingularity.net, aarcange@redhat.com, amit.shah@redhat.com,
        pbonzini@redhat.com, willy@infradead.org, liliang.opensource@gmail.com,
        yang.zhang.wz@gmail.com, quan.xu0@gmail.com, nilal@redhat.com,
        riel@redhat.com
Subject: Re: [PATCH v20 0/7] Virtio-balloon Enhancement
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
References: <1513685879-21823-1-git-send-email-wei.w.wang@intel.com>
In-Reply-To: <1513685879-21823-1-git-send-email-wei.w.wang@intel.com>
Message-Id: <201712192305.AAE21882.MtQHJOFFSFVOLO@I-love.SAKURA.ne.jp>
X-Mailer: Winbiff [Version 2.51 PL2]
X-Accept-Language: ja,en,zh
Date: Tue, 19 Dec 2017 23:05:11 +0900
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 1305
Lines: 35

Wei Wang wrote:
> ChangeLog:
> v19->v20:
> 1) patch 1: xbitmap
> 	- add __rcu to "void **slot";
> 	- remove the exceptional path.
> 2) patch 3: xbitmap
> 	- DeveloperNotes: add an item to comment that the current bit range
> 	  related APIs operating on extremely large ranges (e.g.
>           [0, ULONG_MAX)) will take too long time. This can be optimized in
> 	  the future.
> 	- remove the exceptional path;
> 	- remove xb_preload_and_set();
> 	- reimplement xb_clear_bit_range to make its usage close to
> 	  bitmap_clear;
> 	- rename xb_find_next_set_bit to xb_find_set, and re-implement it
> 	  in a style close to find_next_bit;
> 	- rename xb_find_next_zero_bit to xb_find_clear, and re-implement
> 	  it in a stytle close to find_next_zero_bit;
> 	- separate the implementation of xb_find_set and xb_find_clear for
> 	  the convenience of future updates.

Removing exceptional path made this patch easier to read.
But what I meant is

  Can you eliminate exception path and fold all xbitmap patches into one, and
  post only one xbitmap patch without virtio-balloon changes? 

.

I still think we don't need xb_preload()/xb_preload_end().
I think xb_find_set() has a bug in !node path.

Also, please avoid unconditionally adding to builtin modules.
There are users who want to save even few KB.