From: Keith Busch <keith.busch@intel.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@fb.com>, Sagi Grimberg <sagi@grimberg.me>,
Max Gurtovoy <maxg@mellanox.com>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>
Subject: Re: [PATCH 10/13] nvme-mpath: remove I/O polling support
Date: Mon, 3 Dec 2018 11:22:29 -0700 [thread overview]
Message-ID: <20181203182229.GG14775@localhost.localdomain> (raw)
In-Reply-To: <20181202164628.1116-11-hch@lst.de>
On Sun, Dec 02, 2018 at 08:46:25AM -0800, Christoph Hellwig wrote:
> The ->poll_fn has been stale for a while, as a lot of places check for mq
> ops. But there is no real point in it anyway, as we don't even use
> the multipath code for subsystems without multiple ports, which is usually
> what we do high performance I/O to. If it really becomes an issue we
> should rework the nvme code to also skip the multipath code for any
> private namespace, even if that could mean some trouble when rescanning.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
This was a bit flawed anyway since the head's current path could change,
and you end up polling the wrong request_queue. Not really harmful other
than some wasted CPU cycles, but might be worth thinking about if we
want to bring mpath polling back.
Reviewed-by: Keith Busch <keith.busch@intel.com>
WARNING: multiple messages have this Message-ID (diff)
From: keith.busch@intel.com (Keith Busch)
Subject: [PATCH 10/13] nvme-mpath: remove I/O polling support
Date: Mon, 3 Dec 2018 11:22:29 -0700 [thread overview]
Message-ID: <20181203182229.GG14775@localhost.localdomain> (raw)
In-Reply-To: <20181202164628.1116-11-hch@lst.de>
On Sun, Dec 02, 2018@08:46:25AM -0800, Christoph Hellwig wrote:
> The ->poll_fn has been stale for a while, as a lot of places check for mq
> ops. But there is no real point in it anyway, as we don't even use
> the multipath code for subsystems without multiple ports, which is usually
> what we do high performance I/O to. If it really becomes an issue we
> should rework the nvme code to also skip the multipath code for any
> private namespace, even if that could mean some trouble when rescanning.
>
> Signed-off-by: Christoph Hellwig <hch at lst.de>
This was a bit flawed anyway since the head's current path could change,
and you end up polling the wrong request_queue. Not really harmful other
than some wasted CPU cycles, but might be worth thinking about if we
want to bring mpath polling back.
Reviewed-by: Keith Busch <keith.busch at intel.com>
next prev parent reply other threads:[~2018-12-03 18:25 UTC|newest]
Thread overview: 86+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-02 16:46 block and nvme polling improvements V3 Christoph Hellwig
2018-12-02 16:46 ` Christoph Hellwig
2018-12-02 16:46 ` [PATCH 01/13] block: move queues types to the block layer Christoph Hellwig
2018-12-02 16:46 ` Christoph Hellwig
2018-12-04 0:49 ` Sagi Grimberg
2018-12-04 0:49 ` Sagi Grimberg
2018-12-04 15:00 ` Christoph Hellwig
2018-12-04 15:00 ` Christoph Hellwig
2018-12-04 17:08 ` Sagi Grimberg
2018-12-04 17:08 ` Sagi Grimberg
2018-12-02 16:46 ` [PATCH 02/13] nvme-pci: use atomic bitops to mark a queue enabled Christoph Hellwig
2018-12-02 16:46 ` Christoph Hellwig
2018-12-04 0:54 ` Sagi Grimberg
2018-12-04 0:54 ` Sagi Grimberg
2018-12-04 15:04 ` Christoph Hellwig
2018-12-04 15:04 ` Christoph Hellwig
2018-12-04 17:11 ` Sagi Grimberg
2018-12-04 17:11 ` Sagi Grimberg
2018-12-02 16:46 ` [PATCH 03/13] nvme-pci: cleanup SQ allocation a bit Christoph Hellwig
2018-12-02 16:46 ` Christoph Hellwig
2018-12-04 0:55 ` Sagi Grimberg
2018-12-04 0:55 ` Sagi Grimberg
2018-12-02 16:46 ` [PATCH 04/13] nvme-pci: only allow polling with separate poll queues Christoph Hellwig
2018-12-02 16:46 ` Christoph Hellwig
2018-12-03 18:23 ` Keith Busch
2018-12-03 18:23 ` Keith Busch
2018-12-04 0:56 ` Sagi Grimberg
2018-12-04 0:56 ` Sagi Grimberg
2018-12-02 16:46 ` [PATCH 05/13] nvme-pci: consolidate code for polling non-dedicated queues Christoph Hellwig
2018-12-02 16:46 ` Christoph Hellwig
2018-12-04 0:58 ` Sagi Grimberg
2018-12-04 0:58 ` Sagi Grimberg
2018-12-04 15:04 ` Christoph Hellwig
2018-12-04 15:04 ` Christoph Hellwig
2018-12-04 17:13 ` Sagi Grimberg
2018-12-04 17:13 ` Sagi Grimberg
2018-12-04 18:19 ` Jens Axboe
2018-12-04 18:19 ` Jens Axboe
2018-12-02 16:46 ` [PATCH 06/13] nvme-pci: refactor nvme_disable_io_queues Christoph Hellwig
2018-12-02 16:46 ` Christoph Hellwig
2018-12-04 1:00 ` Sagi Grimberg
2018-12-04 1:00 ` Sagi Grimberg
2018-12-04 15:05 ` Christoph Hellwig
2018-12-04 15:05 ` Christoph Hellwig
2018-12-04 18:19 ` Jens Axboe
2018-12-04 18:19 ` Jens Axboe
2018-12-02 16:46 ` [PATCH 07/13] nvme-pci: don't poll from irq context when deleting queues Christoph Hellwig
2018-12-02 16:46 ` Christoph Hellwig
2018-12-03 18:15 ` Keith Busch
2018-12-03 18:15 ` Keith Busch
2018-12-04 1:05 ` Sagi Grimberg
2018-12-04 1:05 ` Sagi Grimberg
2018-12-02 16:46 ` [PATCH 08/13] nvme-pci: remove the CQ lock for interrupt driven queues Christoph Hellwig
2018-12-02 16:46 ` Christoph Hellwig
2018-12-04 1:08 ` Sagi Grimberg
2018-12-04 1:08 ` Sagi Grimberg
2018-12-02 16:46 ` [PATCH 09/13] nvme-rdma: remove I/O polling support Christoph Hellwig
2018-12-02 16:46 ` Christoph Hellwig
2018-12-02 16:46 ` [PATCH 10/13] nvme-mpath: " Christoph Hellwig
2018-12-02 16:46 ` Christoph Hellwig
2018-12-03 18:22 ` Keith Busch [this message]
2018-12-03 18:22 ` Keith Busch
2018-12-04 1:11 ` Sagi Grimberg
2018-12-04 1:11 ` Sagi Grimberg
2018-12-04 15:07 ` Christoph Hellwig
2018-12-04 15:07 ` Christoph Hellwig
2018-12-04 17:18 ` Sagi Grimberg
2018-12-04 17:18 ` Sagi Grimberg
2018-12-02 16:46 ` [PATCH 11/13] block: remove ->poll_fn Christoph Hellwig
2018-12-02 16:46 ` Christoph Hellwig
2018-12-04 1:11 ` Sagi Grimberg
2018-12-04 1:11 ` Sagi Grimberg
2018-12-02 16:46 ` [PATCH 12/13] block: only allow polling if a poll queue_map exists Christoph Hellwig
2018-12-02 16:46 ` Christoph Hellwig
2018-12-04 1:14 ` Sagi Grimberg
2018-12-04 1:14 ` Sagi Grimberg
2018-12-02 16:46 ` [PATCH 13/13] block: enable polling by default if a poll map is initalized Christoph Hellwig
2018-12-02 16:46 ` Christoph Hellwig
2018-12-04 1:14 ` Sagi Grimberg
2018-12-04 1:14 ` Sagi Grimberg
2018-12-04 18:40 ` block and nvme polling improvements V3 Jens Axboe
2018-12-04 18:40 ` Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2018-11-29 19:12 block and nvme polling improvements V2 Christoph Hellwig
2018-11-29 19:13 ` [PATCH 10/13] nvme-mpath: remove I/O polling support Christoph Hellwig
2018-11-29 19:13 ` Christoph Hellwig
2018-11-21 16:23 block and nvme polling improvements Christoph Hellwig
2018-11-21 16:23 ` [PATCH 10/13] nvme-mpath: remove I/O polling support Christoph Hellwig
2018-11-21 16:23 ` Christoph Hellwig
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