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Date: Wed, 10 Aug 2011 14:18:54 -0400
From: Vivek Goyal <vgoyal@redhat.com>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>, Jan Kara <jack@suse.cz>,
        Christoph Hellwig <hch@lst.de>, Dave Chinner <david@fromorbit.com>,
        Greg Thelen <gthelen@google.com>, Minchan Kim <minchan.kim@gmail.com>,
        Andrea Righi <arighi@develer.com>, linux-mm <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/5] writeback: per task dirty rate limit
Message-ID: <20110810181854.GD3396@redhat.com>
References: <20110806084447.388624428@intel.com>
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 <20110809174621.GF6482@redhat.com>
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On Wed, Aug 10, 2011 at 11:29:54AM +0800, Wu Fengguang wrote:

[..]
> > > -	ratelimit = ratelimit_pages;
> > > -	if (mapping->backing_dev_info->dirty_exceeded)
> > > +	ratelimit = current->nr_dirtied_pause;
> > > +	if (bdi->dirty_exceeded)
> > >  		ratelimit = 8;
> > 
> > Should we make sure that ratelimit is more than 8? It could be that
> > ratelimit is 1 and we set it higher (just reverse of what we wanted?)
> 
> Good catch! I actually just fixed it in that direction :)
> 
>         if (bdi->dirty_exceeded)
> -               ratelimit = 8;
> +               ratelimit = min(ratelimit, 32 >> (PAGE_SHIFT - 10));

With page size 64K, will above lead to retelimit 0? Is that what you want.
I wouldn't think so.

Thanks
Vivek