From mboxrd@z Thu Jan  1 00:00:00 1970
From: Nikita Danilov <danilov@gmail.com>
Subject: Re: [PATCH 30/45] vmscan: lumpy pageout
Date: Wed, 7 Oct 2009 19:50:58 +0400
Message-ID: <8acda98c0910070850x14614e0fh832f5cd29b1588f0@mail.gmail.com>
References: <8acda98c0910070338n7220fdabo8c7f8f9e7d21ef6c@mail.gmail.com>
	 <20091007111454.GB15936@localhost>
	 <8acda98c0910070437g1498f99eua9a5ad71e6c2bae4@mail.gmail.com>
	 <20091007132924.GB20855@localhost> <20091007134254.GA26244@localhost>
	 <20091007142054.GA6798@localhost>
	 <8acda98c0910070750x6428b96fgdeee5946d1408888@mail.gmail.com>
	 <20091007150047.GA9848@localhost>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: QUOTED-PRINTABLE
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Theodore Tso <tytso@mit.edu>,
	Christoph Hellwig <hch@infradead.org>,
	Dave Chinner <david@fromorbit.com>,
	Chris Mason <chris.mason@oracle.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	"Li, Shaohua" <shaohua.li@intel.com>,
	Myklebust Trond <Trond.Myklebust@netapp.com>,
	"jens.axboe@oracle.com" <jens.axboe@oracle.com>,
	Jan Kara <jack@suse.cz>, Nick Piggin <npiggin@suse.de>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
To: Wu Fengguang <fengguang.wu@intel.com>
Return-path: <linux-fsdevel-owner@vger.kernel.org>
Received: from mail-qy0-f202.google.com ([209.85.221.202]:33817 "EHLO
	mail-qy0-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1759374AbZJGPvf convert rfc822-to-8bit (ORCPT
	<rfc822;linux-fsdevel@vger.kernel.org>);
	Wed, 7 Oct 2009 11:51:35 -0400
Received: by qyk40 with SMTP id 40so4384812qyk.22
        for <linux-fsdevel@vger.kernel.org>; Wed, 07 Oct 2009 08:50:59 -0700 (PDT)
In-Reply-To: <20091007150047.GA9848@localhost>
Sender: linux-fsdevel-owner@vger.kernel.org
List-ID: <linux-fsdevel.vger.kernel.org>

2009/10/7 Wu Fengguang <fengguang.wu@intel.com>:

[...]

> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0*/
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (current_is_kswapd() &&
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 bdi_cap_writeback_dirty(mapping=
->backing_dev_info) &&
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 !mapping->a_ops->writepages) {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 wbc.range_start =3D (pa=
ge->index + 1) << PAGE_CACHE_SHIFT;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 wbc.nr_to_write =3D LUM=
PY_PAGEOUT_PAGES - 1;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 generic_writepages(mapp=
ing, &wbc);
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 iput(inode);
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 }
> +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 /*

One potential problem with this is that generic_writepages() waits on
page locks and this can stall kswapd (always bad). This can be worked
around by replacing lock_page() with trylock_page() conditionally on
wbc->for_reclaim (or wbc->nonblocking?), but then, this almost look
like a separate function would be better.

On a good side, it seems I was wrong and pageout calls iput() already:
shrink_slab()->prune_icache()->iput().

Thank you,
Nikita.
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel=
" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html