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From: Keith Busch <kbusch@kernel.org>
To: Ming Lei <ming.lei@redhat.com>
Cc: Sagi Grimberg <sagi@grimberg.me>, Long Li <longli@microsoft.com>,
	"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
	Jens Axboe <axboe@fb.com>, Hannes Reinecke <hare@suse.de>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 2/2] nvme-pci: poll IO after batch submission for multi-mapping queue
Date: Wed, 13 Nov 2019 12:17:02 +0900
Message-ID: <20191113031702.GA25906@redsun51.ssa.fujisawa.hgst.com> (raw)
In-Reply-To: <20191113030520.GC28701@ming.t460p>

On Wed, Nov 13, 2019 at 11:05:20AM +0800, Ming Lei wrote:
> Threaded irq can't help Azure's performance, because Azure's nvme implementation
> applies aggressive interrupt coalescing.

This sounds like QD1 latency is really awful if it's coalescing this way.

Let me restate to ensure I understand how this patch addresses the
high-depth case: by polling during submission, a multi-threaded high
depth workload gets to carve up the number of CQEs handled by spreading
across more CPUs. Real hardware should see fewer completions per
interrupt, but we should be able to recreate this issue by enabling
interrupt coalescing on a real NVMe.

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  reply index

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-08  3:55 [PATCH 0/2] nvme-pci: improve IO performance via poll after batch submission Ming Lei
2019-11-08  3:55 ` [PATCH 1/2] nvme-pci: move sq/cq_poll lock initialization into nvme_init_queue Ming Lei
2019-11-08  4:12   ` Keith Busch
2019-11-08  7:09     ` Ming Lei
2019-11-08  3:55 ` [PATCH 2/2] nvme-pci: poll IO after batch submission for multi-mapping queue Ming Lei
2019-11-11 20:44   ` Christoph Hellwig
2019-11-12  0:33     ` Long Li
2019-11-12  1:35       ` Sagi Grimberg
2019-11-12  2:39       ` Ming Lei
2019-11-12 16:25         ` Hannes Reinecke
2019-11-12 16:49           ` Keith Busch
2019-11-12 17:29             ` Hannes Reinecke
2019-11-13  3:05               ` Ming Lei
2019-11-13  3:17                 ` Keith Busch [this message]
2019-11-13  3:57                   ` Ming Lei
2019-11-12 21:20         ` Long Li
2019-11-12 21:36           ` Keith Busch
2019-11-13  0:50             ` Long Li
2019-11-13  2:24           ` Ming Lei
2019-11-12  2:07     ` Ming Lei
2019-11-12  1:44   ` Sagi Grimberg
2019-11-12  9:56     ` Ming Lei
2019-11-12 17:35       ` Sagi Grimberg
2019-11-12 21:17         ` Long Li
2019-11-12 23:44         ` Jens Axboe
2019-11-13  2:47         ` Ming Lei
2019-11-12 18:11   ` Nadolski, Edmund
2019-11-13 13:46     ` Ming Lei

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