Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Martin Steigerwald <martin@lichtvoll.de>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Matthew Wilcox <mawilcox@microsoft.com>
Subject: Re: XArray documentation
Date:   Fri, 24 Nov 2017 17:50:41 +0100
Message-ID: <3543098.x2GeNdvaH7@merkaba>
In-Reply-To: <20171124011607.GB3722@bombadil.infradead.org>
References: <20171122210739.29916-1-willy@infradead.org> <20171124011607.GB3722@bombadil.infradead.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8BIT
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hello Matthew.

Matthew Wilcox - 24.11.17, 02:16:
> ======
> XArray
> ======
> 
> Overview
> ========
> 
> The XArray is an array of ULONG_MAX entries.  Each entry can be either
> a pointer, or an encoded value between 0 and LONG_MAX.  It is efficient
> when the indices used are densely clustered; hashing the object and
> using the hash as the index will not perform well.  A freshly-initialised
> XArray contains a NULL pointer at every index.  There is no difference
> between an entry which has never been stored to and an entry which has most
> recently had NULL stored to it.

I am no kernel developer (just provided a tiny bit of documentation a long 
time ago)… but on reading into this, I missed:

What is it about? And what is it used for?

"Overview" appears to be already a description of the actual implementation 
specifics, instead of… well an overview.

Of course, I am sure you all know what it is for… but someone who wants to 
learn about the kernel is likely to be confused by such a start.

Thanks,
-- 
Martin

From 1584920406765382634@xxx Fri Nov 24 04:31:25 +0000 2017
X-GM-THRID: 1584908277167360414
X-Gmail-Labels: Inbox,Category Forums,HistoricalUnread