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From: Christoph Hellwig <hch@lst.de>
To: Keith Busch <keith.busch@gmail.com>
Cc: Daniel Drake <drake@endlessm.com>,
	Bjorn Helgaas <bhelgaas@google.com>, Jens Axboe <axboe@kernel.dk>,
	Keith Busch <kbusch@kernel.org>, Christoph Hellwig <hch@lst.de>,
	Linux PCI <linux-pci@vger.kernel.org>,
	linux-ide@vger.kernel.org, Sagi Grimberg <sagi@grimberg.me>,
	linux-nvme <linux-nvme@lists.infradead.org>,
	Linux Upstreaming Team <linux@endlessm.com>
Subject: Re: [PATCH] PCI: Add Intel remapped NVMe device support
Date: Thu, 13 Jun 2019 10:54:02 +0200
Message-ID: <20190613085402.GC13442@lst.de> (raw)
In-Reply-To: <CAOSXXT7H6HxY-za66Tr9ybRQyHsTdwwAgk9O2F=xK42MT8HsuA@mail.gmail.com>

On Wed, Jun 12, 2019 at 08:32:46AM -0600, Keith Busch wrote:
> On Mon, Jun 10, 2019 at 8:46 PM Daniel Drake <drake@endlessm.com> wrote:
> > What's the specific problem that you see here?
> 
> Performance. Have you had a chance to benchmark these storage devices
> comparing legacy vs MSI interrupts? I don't think anyone would chose
> the slower one on purpose. These platforms have an option to disable
> raid mode, so the kernel's current recommendation should be the user's
> best option.

And it isn't just performance.  I really don't understand how

 a) quirks on the PCI ID
 b) reset handling, including the PCI device removal as the last
    escalation step
 c) SR-IOV VFs and their management
 d) power management

and probably various other bits I didn't even think of are going to
work.

So until we get very clear and good documentation from Intel on that
I don't think any form of upstream support will fly.  And given that
Dan who submitted the original patch can't even talk about this thing
any more and apparently got a gag order doesn't really give me confidence
any of this will ever work.

  reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-10  7:44 Daniel Drake
2019-06-10 16:00 ` Keith Busch
2019-06-11  2:46   ` Daniel Drake
2019-06-12 14:32     ` Keith Busch
2019-06-13  8:54       ` Christoph Hellwig [this message]
2019-06-14  2:26         ` Daniel Drake
2019-06-14 19:36           ` Keith Busch
2019-06-14 20:05             ` Bjorn Helgaas
2019-06-14 21:05               ` Keith Busch
2019-06-18  7:48                 ` Hannes Reinecke
2019-06-18  7:46           ` Hannes Reinecke
2019-06-18  8:06             ` Daniel Drake
2019-06-18 15:15               ` Hannes Reinecke
2019-06-19 13:52                 ` Bjorn Helgaas
2019-06-10 21:16 ` Bjorn Helgaas
2019-06-11  3:25   ` Daniel Drake
2019-06-11 19:52     ` Bjorn Helgaas
2019-06-12  3:16       ` Daniel Drake
2019-06-12 13:49         ` Bjorn Helgaas

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