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From: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
To: Sagi Grimberg <sagi-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>
Cc: linux-nvme-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
	linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Jens Axboe <axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org>,
	Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>,
	Steve Wise
	<swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>,
	Jay Freyensee
	<james_p_freyensee-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>,
	Ming Lin <mlin-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Subject: Re: [PATCH] nvmet-rdma: Don't use the inline buffer in order to avoid allocation for small reads
Date: Tue, 2 Aug 2016 14:50:42 +0200	[thread overview]
Message-ID: <20160802125042.GB13235@lst.de> (raw)
In-Reply-To: <1470040599-7294-1-git-send-email-sagi-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>

On Mon, Aug 01, 2016 at 11:36:39AM +0300, Sagi Grimberg wrote:
> Under extreme conditions this might cause data corruptions. By doing that
> we we repost the buffer and then post this buffer for the device to send.
> If we happen to use shared receive queues the device might write to the
> buffer before it sends it (there is no ordering between send and recv
> queues). Without SRQs we probably won't get that if the host doesn't
> mis-behave and send more than we allowed it, but relying on that is not
> really a good idea.

Pitty - it seems so wasteful not being able to use these buffers for
anything that isn't an inline write.  I fully agree on the SRQ case,
but I think we should offer it for the non-SRP case.
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  parent reply	other threads:[~2016-08-02 12:50 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-01  8:36 [PATCH] nvmet-rdma: Don't use the inline buffer in order to avoid allocation for small reads Sagi Grimberg
     [not found] ` <1470040599-7294-1-git-send-email-sagi-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>
2016-08-02 12:50   ` Christoph Hellwig [this message]
     [not found]     ` <20160802125042.GB13235-jcswGhMUV9g@public.gmane.org>
2016-08-02 13:38       ` Sagi Grimberg
     [not found]         ` <157675f0-0576-1cc9-1f99-c0944185e3c5-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>
2016-08-02 16:15           ` Jason Gunthorpe
     [not found]             ` <20160802161526.GA14964-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2016-08-03  9:48               ` Sagi Grimberg
2016-08-03  9:49               ` Christoph Hellwig
     [not found]                 ` <20160803094941.GA11821-jcswGhMUV9g@public.gmane.org>
2016-08-03 10:37                   ` Sagi Grimberg
2016-08-04 11:49   ` Christoph Hellwig

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