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Date:   Tue, 27 Apr 2021 00:15:37 +0900
From:   Keith Busch <kbusch@kernel.org>
To:     Christoph Hellwig <hch@lst.de>
Cc:     linux-nvme@lists.infradead.org, sagi@grimberg.me, axboe@kernel.dk,
        linux-block@vger.kernel.org,
        Yuanyuan Zhong <yzhong@purestorage.com>,
        Casey Chen <cachen@purestorage.com>
Subject: Re: [PATCHv2 5/5] nvme: allow user passthrough commands to poll
Message-ID: <20210426151537.GB12593@redsun51.ssa.fujisawa.hgst.com>
References: <20210423220558.40764-1-kbusch@kernel.org>
 <20210423220558.40764-6-kbusch@kernel.org>
 <20210426144316.GE20668@lst.de>
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On Mon, Apr 26, 2021 at 04:43:16PM +0200, Christoph Hellwig wrote:
> On Fri, Apr 23, 2021 at 03:05:58PM -0700, Keith Busch wrote:
> > The block layer knows how to deal with polled requests. Let the NVMe
> > driver use the previously reserved user "flags" fields to define an
> > option to allocate the request from the polled hardware contexts. If
> > polling is not enabled, then the block layer will automatically fallback
> > to a non-polled request.
> 
> So this only support synchronous polling for a single command.  What
> use case do we have for that?  I think io_uring based polling would
> be much more useful once we support NVMe passthrough through that.

There is no significant use case here. I just needed a simple way to
test the polled exec from earlier in the series. It was simple enough so
I included the patch here, but it's really not important compared to the
preceeding patches.