Subject: Re: [PATCH 4/8] writeback: track if we're sleeping on progress in
 balance_dirty_pages()
To: Christoph Hellwig <hch@lst.de>
References: <1478034531-28559-1-git-send-email-axboe@fb.com>
 <1478034531-28559-5-git-send-email-axboe@fb.com>
 <20161102145703.GH13964@lst.de>
CC: <axboe@kernel.dk>, <linux-kernel@vger.kernel.org>,
        <linux-fsdevel@vger.kernel.org>, <linux-block@vger.kernel.org>,
        <jack@suse.cz>
From: Jens Axboe <axboe@fb.com>
Message-ID: <43669b76-06b0-8dd5-8334-a40936b47e6a@fb.com>
Date: Wed, 2 Nov 2016 08:59:20 -0600
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
 Thunderbird/45.4.0
MIME-Version: 1.0
In-Reply-To: <20161102145703.GH13964@lst.de>
Content-Type: text/plain; charset="windows-1252"; format=flowed
Content-Transfer-Encoding: 7bit
SpamDiagnosticOutput: 1:99
SpamDiagnosticMetadata: NSPM
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Nov 2016 14:59:26.5523 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY4PR15MB1192
X-OriginatorOrg: fb.com
X-Proofpoint-Spam-Reason: safe
X-FB-Internal: Safe
X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-11-02_03:,,
 signatures=0
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 515
Lines: 16

On 11/02/2016 08:57 AM, Christoph Hellwig wrote:
> On Tue, Nov 01, 2016 at 03:08:47PM -0600, Jens Axboe wrote:
>> Note in the bdi_writeback structure whenever a task ends up sleeping
>> waiting for progress. We can use that information in the lower layers
>> to increase the priority of writes.
>
> Do we need to care about atomicy of multiple threads updating the value
> ?
>
> Otherwise this looks fine.

Don't think we have to care about it too much, it's a soft hint similar
wb->dirty_exceeded.

-- 
Jens Axboe