From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeff Moyer <jmoyer@redhat.com>
Subject: Re: [PATCH] block_dev: implement readpages() to optimize sequential read
Date: Thu, 17 Jul 2014 14:31:56 -0400
Message-ID: <x49pph325wj.fsf@segfault.boston.devel.redhat.com>
References: <1405606659-3802-1-git-send-email-akinobu.mita@gmail.com>
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Cc: linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Jens Axboe <axboe@kernel.dk>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	linux-fsdevel@vger.kernel.org
To: Akinobu Mita <akinobu.mita@gmail.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <1405606659-3802-1-git-send-email-akinobu.mita@gmail.com>
	(Akinobu Mita's message of "Thu, 17 Jul 2014 23:17:39 +0900")
Sender: linux-kernel-owner@vger.kernel.org
List-Id: linux-fsdevel.vger.kernel.org

Akinobu Mita <akinobu.mita@gmail.com> writes:

> Sequential read from a block device is expected to be equal or faster
> than from the file on a filesystem.  But it is not correct due to the
> lack of effective readpages() in the address space operations for
> block device.

Ah, a trip down memory lane.  ;-)  Here's a thread showing issues with
the last time this was proposed (by me, incidentally):

https://lkml.org/lkml/2009/6/2/480

At the very least, we need to see numbers on a real device, and see it
booted on something with >4k page size before taking this back in.

Cheers,
Jeff