Date: Sun, 5 Feb 2006 22:36:11 -0800
From: Andrew Morton <akpm@osdl.org>
To: dgc@sgi.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
       Nathan Scott <nathans@sgi.com>
Subject: Re: [PATCH] Prevent large file writeback starvation
Message-Id: <20060205223611.5789a062.akpm@osdl.org>
In-Reply-To: <20060205222215.313f30a9.akpm@osdl.org>
References: <20060206040027.GI43335175@melbourne.sgi.com>
	<20060205202733.48a02dbe.akpm@osdl.org>
	<20060206054815.GJ43335175@melbourne.sgi.com>
	<20060205222215.313f30a9.akpm@osdl.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1095
Lines: 32

Andrew Morton <akpm@osdl.org> wrote:
>
> If so, why would that happen?  Take a look at wb_kupdate().  It's supposed
>  to work *continuously* on the inodes until writeback_inodes() failed to
>  write back enough pages.  It takes this as an indication that there's no
>  more work to do at this time.
> 
>  It'd be interesting to take a look at what's happening in wb_kupdate().

Took a quick look at xfs_convert_page().  I don't immediately see a cause
in there, but

		if (count) {
			struct backing_dev_info *bdi;

			bdi = inode->i_mapping->backing_dev_info;
			if (bdi_write_congested(bdi)) {
				wbc->encountered_congestion = 1;
				done = 1;
			} else if (--wbc->nr_to_write <= 0) {
				done = 1;
			}
		}
		xfs_start_page_writeback(page, wbc, !page_dirty, count);

shouldn't we be decrementing wbc->nr_to_write even if the queue is congested?

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/