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From: swise@opengridcomputing.com (Steve Wise)
Subject: Flush warning
Date: Mon, 14 Aug 2017 12:21:40 -0500	[thread overview]
Message-ID: <00be01d31521$cb237900$616a6b00$@opengridcomputing.com> (raw)
In-Reply-To: <1828884A29C6694DAF28B7E6B8A82373AB17595A@ORSMSX109.amr.corp.intel.com>

> > >>> The workqueue which frees the memory and doesn't allocate memory
> > >>> during execution is supposed to be marked as WQ_MEM_RECLAIM. This
> > >>> flag will cause to priority increase for such workqueue during low
> > memory conditions.
> > >>
> > >> Which to my understanding means that CM workqueue should not use it
> > >> as on each CM connect, by definition the ULP allocates memory (qp,
> > cq etc).
> > >
> > > From my understanding too.
> > > That workqueue was introduced in 2005, in a977049dacde ("[PATCH] IB:
> > > Add the kernel CM implementation"), it is not clear if it was
> > > intentionally.
> > >
> > > Hal,
> > > do you remember the rationale there?
> >
> > Sean is best to respond to this.
> 
> I believe the work queue was to avoid potential deadlocks that could arise
from
> using the MAD work queue.  The original submission did not mark the work queue
> with WQ_MEM_RECLAIM.  I do not know when that change was added.

By the way, the queue I'm actually having the problem with is in the iwcm, not
the ibcm.  I think we should remove WQ_MEM_RECLAIM from all the CM queues
because I agree now that ulps potentially can/will allocate memory in the
contect of these workqueues...

WARNING: multiple messages have this Message-ID (diff)
From: "Steve Wise" <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
To: "'Hefty,
	Sean'" <sean.hefty-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	'Hal Rosenstock'
	<hal-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>,
	'Leon Romanovsky' <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	'Sagi Grimberg' <sagi-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>,
	'Hal Rosenstock' <hal-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Cc: 'Jason Gunthorpe'
	<jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>,
	linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-nvme-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
	'Christoph Hellwig' <hch-jcswGhMUV9g@public.gmane.org>
Subject: RE: Flush warning
Date: Mon, 14 Aug 2017 12:21:40 -0500	[thread overview]
Message-ID: <00be01d31521$cb237900$616a6b00$@opengridcomputing.com> (raw)
In-Reply-To: <1828884A29C6694DAF28B7E6B8A82373AB17595A-P5GAC/sN6hkd3b2yrw5b5LfspsVTdybXVpNB7YpNyf8@public.gmane.org>

> > >>> The workqueue which frees the memory and doesn't allocate memory
> > >>> during execution is supposed to be marked as WQ_MEM_RECLAIM. This
> > >>> flag will cause to priority increase for such workqueue during low
> > memory conditions.
> > >>
> > >> Which to my understanding means that CM workqueue should not use it
> > >> as on each CM connect, by definition the ULP allocates memory (qp,
> > cq etc).
> > >
> > > From my understanding too.
> > > That workqueue was introduced in 2005, in a977049dacde ("[PATCH] IB:
> > > Add the kernel CM implementation"), it is not clear if it was
> > > intentionally.
> > >
> > > Hal,
> > > do you remember the rationale there?
> >
> > Sean is best to respond to this.
> 
> I believe the work queue was to avoid potential deadlocks that could arise
from
> using the MAD work queue.  The original submission did not mark the work queue
> with WQ_MEM_RECLAIM.  I do not know when that change was added.

By the way, the queue I'm actually having the problem with is in the iwcm, not
the ibcm.  I think we should remove WQ_MEM_RECLAIM from all the CM queues
because I agree now that ulps potentially can/will allocate memory in the
contect of these workqueues...


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  reply	other threads:[~2017-08-14 17:21 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-03 18:32 Flush warning Steve Wise
2017-08-03 18:32 ` Steve Wise
2017-08-07  1:06 ` Sagi Grimberg
2017-08-07  1:06   ` Sagi Grimberg
2017-08-07 15:28   ` Steve Wise
2017-08-07 15:28     ` Steve Wise
2017-08-09 16:21     ` Steve Wise
2017-08-09 16:21       ` Steve Wise
2017-08-09 16:27       ` Jason Gunthorpe
2017-08-09 16:27         ` Jason Gunthorpe
2017-08-09 16:38         ` Steve Wise
2017-08-09 16:38           ` Steve Wise
2017-08-13  6:46           ` Leon Romanovsky
2017-08-13  6:46             ` Leon Romanovsky
2017-08-13  9:14             ` Sagi Grimberg
2017-08-13  9:14               ` Sagi Grimberg
2017-08-13 10:33               ` Leon Romanovsky
2017-08-13 10:33                 ` Leon Romanovsky
2017-08-14 12:13                 ` Hal Rosenstock
2017-08-14 12:13                   ` Hal Rosenstock
2017-08-14 17:01                   ` Hefty, Sean
2017-08-14 17:01                     ` Hefty, Sean
2017-08-14 17:21                     ` Steve Wise [this message]
2017-08-14 17:21                       ` Steve Wise
2017-08-15  9:09                       ` Sagi Grimberg
2017-08-15  9:09                         ` Sagi Grimberg
2017-08-15 13:42                         ` Steve Wise
2017-08-15 13:42                           ` Steve Wise

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