From: Christoph Hellwig <hch@lst.de>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>,
John Garry <john.garry@huawei.com>,
Ming Lei <ming.lei@redhat.com>, Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, linux-nvme@lists.infradead.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Bjorn Helgaas <bhelgaas@google.com>,
linux-pci@vger.kernel.org, Sagi Grimberg <sagi@grimberg.me>,
Daniel Wagner <dwagner@suse.de>, Wen Xiong <wenxiong@us.ibm.com>,
Hannes Reinecke <hare@suse.de>, Keith Busch <kbusch@kernel.org>
Subject: Re: [PATCH V4 1/3] driver core: mark device as irq affinity managed if any irq is managed
Date: Wed, 21 Jul 2021 22:32:59 +0200 [thread overview]
Message-ID: <20210721203259.GA18960@lst.de> (raw)
In-Reply-To: <871r7rqva6.ffs@nanos.tec.linutronix.de>
On Wed, Jul 21, 2021 at 10:14:25PM +0200, Thomas Gleixner wrote:
> https://lore.kernel.org/r/87o8bxcuxv.ffs@nanos.tec.linutronix.de
>
> TLDR: virtio allocates ONE irq on msix_enable() and then when the guest
> actually unmasks another entry (e.g. request_irq()), it tears down the
> allocated one and set's up two. On the third one this repeats ....
>
> There are only two options:
>
> 1) allocate everything upfront, which is undesired
> 2) append entries, which might need locking, but I'm still trying to
> avoid that
>
> There is another problem vs. vector exhaustion which can't be fixed that
> way, but that's a different story.
FTI, NVMe is similar. We need one IRQ to setup the admin queue,
which is used to query/set how many I/O queues are supported. Just
two steps though and not unbound.
next prev parent reply other threads:[~2021-07-21 20:33 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-15 12:08 [PATCH V4 0/3] blk-mq: fix blk_mq_alloc_request_hctx Ming Lei
2021-07-15 12:08 ` [PATCH V4 1/3] driver core: mark device as irq affinity managed if any irq is managed Ming Lei
2021-07-15 12:40 ` Greg Kroah-Hartman
2021-07-16 2:17 ` Ming Lei
2021-07-16 20:01 ` Bjorn Helgaas
2021-07-17 9:30 ` Ming Lei
2021-07-21 0:30 ` Bjorn Helgaas
2021-07-19 7:51 ` John Garry
2021-07-19 9:44 ` Christoph Hellwig
2021-07-19 10:39 ` John Garry
2021-07-20 2:38 ` Ming Lei
2021-07-21 7:20 ` Thomas Gleixner
2021-07-21 7:24 ` Christoph Hellwig
2021-07-21 9:44 ` John Garry
2021-07-21 20:22 ` Thomas Gleixner
2021-07-22 7:48 ` John Garry
2021-07-21 20:14 ` Thomas Gleixner
2021-07-21 20:32 ` Christoph Hellwig [this message]
2021-07-21 22:38 ` Thomas Gleixner
2021-07-22 7:46 ` Christoph Hellwig
2021-07-15 12:08 ` [PATCH V4 2/3] blk-mq: mark if one queue map uses managed irq Ming Lei
2021-07-15 12:08 ` [PATCH V4 3/3] blk-mq: don't deactivate hctx if managed irq isn't used Ming Lei
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