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Subject: Re: [RFC] /dev/ioasid uAPI proposal
To:     Jason Gunthorpe <jgg@nvidia.com>
Cc:     "Tian, Kevin" <kevin.tian@intel.com>,
        Lu Baolu <baolu.lu@linux.intel.com>,
        Liu Yi L <yi.l.liu@linux.intel.com>,
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        Jonathan Corbet <corbet@lwn.net>,
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        LKML <linux-kernel@vger.kernel.org>,
        "Alex Williamson (alex.williamson@redhat.com)\"\"" 
        <alex.williamson@redhat.com>, David Woodhouse <dwmw2@infradead.org>
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From:   Jason Wang <jasowang@redhat.com>
Message-ID: <f69137e3-0f60-4f73-a0ff-8e57c79675d5@redhat.com>
Date:   Wed, 2 Jun 2021 16:54:26 +0800
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?? 2021/6/2 ????1:31, Jason Gunthorpe д??:
> On Tue, Jun 01, 2021 at 04:47:15PM +0800, Jason Wang wrote:
>   
>> We can open up to ~0U file descriptors, I don't see why we need to restrict
>> it in uAPI.
> There are significant problems with such large file descriptor
> tables. High FD numbers man things like select don't work at all
> anymore and IIRC there are more complications.


I don't see how much difference for IOASID and other type of fds. People 
can choose to use poll or epoll.

And with the current proposal, (assuming there's a N:1 ioasid to 
ioasid). I wonder how select can work for the specific ioasid.

Thanks


>
> A huge number of FDs for typical usages should be avoided.
>
> Jason
>