linux-kernel - Re: [PATCH v10 4/4] ipc: Add a cyclic mode for id generation

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Message-ID: <20181106130252.GC3074@bombadil.infradead.org>
Date:   Tue, 6 Nov 2018 05:02:52 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     Waiman Long <longman@...hat.com>
Cc:     "Luis R. Rodriguez" <mcgrof@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jonathan Corbet <corbet@....net>, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-doc@...r.kernel.org,
        Al Viro <viro@...iv.linux.org.uk>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Takashi Iwai <tiwai@...e.de>, Davidlohr Bueso <dbueso@...e.de>,
        Manfred Spraul <manfred@...orfullife.com>
Subject: Re: [PATCH v10 4/4] ipc: Add a cyclic mode for id generation

On Mon, Nov 05, 2018 at 10:43:46AM -0500, Waiman Long wrote:
> The idea of using the cyclic mode to reduce id reuse came from Manfred
> Spraul <manfred@...orfullife.com>. There may be a little bit of
> additional memory/performance overhead in doing cyclic id allocation,
> but it is a slow path anyway and a bit of overhead shouldn't be an issue.
> 
> This patch differs from his as the cyclic mode is not the default and
> has to be explicitly opted in for users who want that.

I really don't like the "make the sysadmin choose" approach.  It's
shifting blame to someone who has no idea what the tradeoffs are.
We should try to get it right rather than force more people to learn
why we're incapable of making the right decision for them.