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From: Bruce Fields <bfields@fieldses.org>
To: Chuck Lever III <chuck.lever@oracle.com>
Cc: Neil Brown <neilb@suse.de>, Matthew Wilcox <willy@infradead.org>,
	Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
	Mel Gorman <mgorman@suse.com>, Linux-MM <linux-mm@kvack.org>
Subject: Re: [PATCH] SUNRPC: use congestion_wait() in svc_alloc_args()
Date: Tue, 7 Sep 2021 11:39:44 -0400	[thread overview]
Message-ID: <20210907153944.GA1364@fieldses.org> (raw)
In-Reply-To: <8ED6E493-21A6-46BC-810A-D9DA42996979@oracle.com>

On Tue, Sep 07, 2021 at 02:53:48PM +0000, Chuck Lever III wrote:
> 
> 
> > On Sep 6, 2021, at 8:41 PM, NeilBrown <neilb@suse.de> wrote:
> > 
> > When does a single-page GFP_KERNEL allocation fail?  Ever?
> > 
> > I know that if I add __GFP_NOFAIL then it won't fail and that is
> > preferred to looping.
> > I know that if I add __GFP_RETRY_MAILFAIL (or others) then it might
> > fail.
> > But that is the semantics for a plain GFP_KERNEL ??
> > 
> > I recall a suggestion one that it would only fail if the process was
> > being killed by the oom killer.  That seems reasonable and would suggest
> > that retrying is really bad.  Is that true?
> > 
> > For svc_alloc_args(), it might be better to fail and have the calling
> > server thread exit.  This would need to be combined with dynamic
> > thread-count management so that when a request arrived, a new thread
> > might be started.
> 
> I don't immediately see a benefit to killing server threads
> during periods of memory exhaustion, but sometimes I lack
> imagination.

Give up parallelism in return for at least hope of forward progress?
(Which should be possible as long as there's at least one server
thread.)

--b.

  reply	other threads:[~2021-09-07 15:39 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-06  4:44 [PATCH] SUNRPC: use congestion_wait() in svc_alloc_args() NeilBrown
2021-09-06 15:46 ` Chuck Lever III
2021-09-06 20:20   ` Matthew Wilcox
2021-09-06 22:13     ` Bruce Fields
2021-09-06 22:22     ` NeilBrown
2021-09-07  0:41       ` NeilBrown
2021-09-07 14:53         ` Chuck Lever III
2021-09-07 15:39           ` Bruce Fields [this message]
2021-09-07 15:41           ` Mel Gorman
2021-09-07 16:21             ` Chuck Lever III
2021-09-07 21:47           ` NeilBrown
2021-09-07  8:17       ` Mel Gorman
2021-09-06 21:52   ` NeilBrown

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