From: John Garry <john.garry@huawei.com>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>, <linux-block@vger.kernel.org>,
<linux-nvme@lists.infradead.org>, Christoph Hellwig <hch@lst.de>,
"Sagi Grimberg" <sagi@grimberg.me>,
Daniel Wagner <dwagner@suse.de>, Wen Xiong <wenxiong@us.ibm.com>
Subject: Re: [PATCH 1/2] blk-mq: not deactivate hctx if the device doesn't use managed irq
Date: Wed, 30 Jun 2021 10:25:41 +0100 [thread overview]
Message-ID: <adf34d6d-b209-78d3-8df9-4e3398e34612@huawei.com> (raw)
In-Reply-To: <YNu7rs7j5/KtQjAi@T590>
On 30/06/2021 01:32, Ming Lei wrote:
>> Many block drivers don't use managed interrupts - to be proper, why not set
>> this everywhere (which doesn't use managed interrupts)? I know why, but it's
>> odd.
> It is just one small optimization in slow path for other drivers, not sure these
> drivers are interested in such change. It only serves as fix for callers of
> blk_mq_alloc_request_hctx().
>
> Anyway, we can document the situation.
>
>> As an alternative, if the default queue mapping was used (in
>> blk_mq_map_queues()), then that's the same thing as
>> BLK_MQ_F_NOT_USE_MANAGED_IRQ in reality, right? If so, could we
>> alternatively check for that somehow?
> This way can't work, for example of NVMe PCI, managed irq is used for
> the default/write queues, but poll queues uses blk_mq_map_queues().
>
> Also it can't cover all cases, such as MVMe RDMA.
>
> Using managed irq or not is thing of driver's choice, and not sure if it
> is good for block layer to provide such abstract. I'd suggest to fix the
> issue still by passing one flag, given we needn't it everywhere so far.
Sure, but I am just trying to suggest a more automatic way of passing
this info. Like, for example, if we use blk_mq_pci_map_queues() on the
qmap, then you prob want blk-mq managed interrupt support (for that
qmap), i.e. CPU hotplug handlers.
Thanks,
John
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next prev parent reply other threads:[~2021-06-30 9:32 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-29 7:49 [PATCH 0/2] blk-mq: fix blk_mq_alloc_request_hctx Ming Lei
2021-06-29 7:49 ` [PATCH 1/2] blk-mq: not deactivate hctx if the device doesn't use managed irq Ming Lei
2021-06-29 12:39 ` Hannes Reinecke
2021-06-29 14:17 ` Ming Lei
2021-06-29 15:49 ` John Garry
2021-06-30 0:32 ` Ming Lei
2021-06-30 9:25 ` John Garry [this message]
2021-07-01 9:52 ` Christoph Hellwig
2021-06-29 23:30 ` Damien Le Moal
2021-06-30 18:58 ` Sagi Grimberg
2021-06-30 21:57 ` Damien Le Moal
2021-07-01 14:20 ` Keith Busch
2021-06-29 7:49 ` [PATCH 2/2] nvme: pass BLK_MQ_F_NOT_USE_MANAGED_IRQ for fc/rdma/tcp/loop Ming Lei
2021-06-30 8:15 ` Hannes Reinecke
2021-06-30 8:47 ` Ming Lei
2021-06-30 8:18 ` [PATCH 0/2] blk-mq: fix blk_mq_alloc_request_hctx Hannes Reinecke
2021-06-30 8:42 ` Ming Lei
2021-06-30 9:43 ` Hannes Reinecke
2021-06-30 9:53 ` Ming Lei
2021-06-30 18:59 ` Sagi Grimberg
2021-06-30 19:46 ` Hannes Reinecke
2021-06-30 23:59 ` Ming Lei
2021-07-01 8:00 ` Hannes Reinecke
2021-07-01 9:13 ` Ming Lei
2021-07-02 9:47 ` Daniel Wagner
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