Re: [PATCH v4 00/11] simplify block layer based on immutable biovecs

From: Christoph Hellwig <hch@lst.de>
To: Ming Lin <mlin@kernel.org>
Cc: linux-kernel@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
	Kent Overstreet <kent.overstreet@gmail.com>,
	Jens Axboe <axboe@kernel.dk>, Dongsu Park <dpark@posteo.net>
Subject: Re: [PATCH v4 00/11] simplify block layer based on immutable biovecs
Date: Sat, 23 May 2015 16:15:22 +0200	[thread overview]
Message-ID: <20150523141522.GA19470@lst.de> (raw)
In-Reply-To: <1432318723-18829-1-git-send-email-mlin@kernel.org>

On Fri, May 22, 2015 at 11:18:32AM -0700, Ming Lin wrote:
> This will bring not only performance improvements, but also a great amount
> of reduction in code complexity all over the block layer. Performance gain
> is possible due to the fact that bio_add_page() does not have to check
> unnecesary conditions such as queue limits or if biovecs are mergeable.
> Those will be delegated to the driver level. Kent already said that he
> actually benchmarked the impact of this with fio on a micron p320h, which
> showed definitely a positive impact.

We'll need some actual numbers.  I actually like these changes a lot
and don't even need a performance justification for this fundamentally
better model, but I'd really prefer to avoid any large scale regressions.
I don't really expect them, but for code this fundamental we'll just
need some benchmarks.

Except for that these changes looks good, and the previous version
passed my tests fine, so with some benchmarks you'ĺl have my ACK.

I'd love to see this go into 4.2, but for that we'll need Jens
approval and a merge into for-next very soon.