linux-kernel - Re: [RFD] workqueue: WQ_MEM_RECLAIM usage in network drivers

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Message-ID: <20160320185507.GT20028@mtj.duckdns.org>
Date:	Sun, 20 Mar 2016 14:55:07 -0400
From:	Tejun Heo <tj@...nel.org>
To:	"J. Bruce Fields" <bfields@...ldses.org>
Cc:	Jeff Layton <jlayton@...chiereds.net>,
	"David S. Miller" <davem@...emloft.net>,
	Trond Myklebust <trond.myklebust@...marydata.com>,
	Anna Schumaker <anna.schumaker@...app.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-nfs@...r.kernel.org,
	Amitoj Kaur Chawla <amitoj1606@...il.com>,
	kernel-team@...com, Johannes Weiner <hannes@...xchg.org>,
	Johannes Berg <johannes@...solutions.net>,
	Eva Rachel Retuya <eraretuya@...il.com>,
	Bhaktipriya Shridhar <bhaktipriya96@...il.com>,
	linux-wireless@...r.kernel.org
Subject: Re: [RFD] workqueue: WQ_MEM_RECLAIM usage in network drivers

Hello,

On Fri, Mar 18, 2016 at 05:24:05PM -0400, J. Bruce Fields wrote:
> > But does that actually work?  It's pointless to add WQ_MEM_RECLAIM to
> > workqueues unless all other things are also guaranteed to make forward
> > progress regardless of memory pressure.
> 
> It's supposed to work.
> 
> Also note there was a bunch of work done to allow swap on NFS: see
> a564b8f0 "nfs: enable swap on NFS".

Alright, WQ_MEM_RECLAIM for ethernet devices, then.

> I use NFS mounts over wifi at home.  I may just be odd.  I seem to
> recall some bug reports about suspend vs. NFS--were those also on
> laptops using NFS?
> 
> I wonder if home media centers might do writes over wifi to network
> storage?
> 
> Googling for "nfs wifi" turns up lots of individuals doing this.
> 
> My first impulse is to say that it's probably not perfect but that we
> shouldn't make it worse.

If everything else is working, I'd be happy to throw in WQ_MEM_RECLAIM
but I really don't want to add it if it doesn't actually achieve the
goal.  Can a wireless person chime in here?

Thanks.

-- 
tejun