Date: Sat, 15 Jul 2017 08:28:41 -0700
From: Davidlohr Bueso <dave@stgolabs.net>
To: Christoph Hellwig <hch@infradead.org>
Cc: mingo@kernel.org, peterz@infradead.org, akpm@linux-foundation.org,
        torvalds@linux-foundation.org, jack@suse.cz,
        kirill.shutemov@linux.intel.com, ldufour@linux.vnet.ibm.com,
        mhocko@suse.com, mgorman@techsingularity.net,
        linux-kernel@vger.kernel.org, Davidlohr Bueso <dbueso@suse.de>
Subject: Re: [PATCH 1/9] rbtree: Cache leftmost node internally
Message-ID: <20170715152841.GA14395@linux-80c1.suse>
References: <20170629171553.2146-1-dave@stgolabs.net>
 <20170629171553.2146-2-dave@stgolabs.net>
 <20170715105433.GA31814@infradead.org>
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On Sat, 15 Jul 2017, Christoph Hellwig wrote:

>Is the leftmost node so much more special than the rightmost one?
>
>Just asking because I have some code that caches both of them, but
>using your helpers would make it look very asymmetric..

Yeah, I thought of this, but ultimately decided that the leftmost
node was more used (rb_first vs rb_last calls) and probably not
worth adding the rightmost one which would endup enlarging the
structure even more.

That said, I do have some patches for the rbtree users to cache the
rightmost node, similarly to how it was done with the leftmost
before this patchset.

If folks don't mind enlarging rb_root_cached, I could definitely
add the rightmost, but it seems an overkill -- albeit asymmetric.

Thanks,
Davidlohr