From: jthumshirn@suse.de (Johannes Thumshirn)
Subject: [PATCH 2/3] nvme: don't poll the CQ from the kthread
Date: Thu, 18 Feb 2016 09:34:37 +0100 [thread overview]
Message-ID: <20160218083437.GO18134@c203.arch.suse.de> (raw)
In-Reply-To: <1455732194-30790-3-git-send-email-hch@lst.de>
On Wed, Feb 17, 2016@07:03:13PM +0100, Christoph Hellwig wrote:
> There is no reason to do unconditional polling of CQs per the NVMe
> spec.
>
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> ---
> drivers/nvme/host/pci.c | 12 ------------
> 1 file changed, 12 deletions(-)
>
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index 21b0be4..10839f7 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -1156,9 +1156,6 @@ static struct nvme_queue *nvme_alloc_queue(struct nvme_dev *dev, int qid,
> nvmeq->qid = qid;
> nvmeq->cq_vector = -1;
> dev->queues[qid] = nvmeq;
> -
> - /* make sure queue descriptor is set before queue count, for kthread */
> - mb();
> dev->queue_count++;
>
> return nvmeq;
> @@ -1345,7 +1342,6 @@ static int nvme_kthread(void *data)
> set_current_state(TASK_INTERRUPTIBLE);
> spin_lock(&dev_list_lock);
> list_for_each_entry_safe(dev, next, &dev_list, node) {
> - int i;
> u32 csts = readl(dev->bar + NVME_REG_CSTS);
>
> /*
> @@ -1363,14 +1359,6 @@ static int nvme_kthread(void *data)
> }
> continue;
> }
> - for (i = 0; i < dev->queue_count; i++) {
> - struct nvme_queue *nvmeq = dev->queues[i];
> - if (!nvmeq)
> - continue;
> - spin_lock_irq(&nvmeq->q_lock);
> - nvme_process_cq(nvmeq);
> - spin_unlock_irq(&nvmeq->q_lock);
> - }
> }
> spin_unlock(&dev_list_lock);
> schedule_timeout(round_jiffies_relative(HZ));
> --
> 2.1.4
>
>
> _______________________________________________
> Linux-nvme mailing list
> Linux-nvme at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-nvme
Oh yeah, I was hunting down a lockup in that loop ("fixable" with
touch_nmi_watchdog()). Highly appreciate it's gone.
Reviewed-by: Johannes Thumshirn <jthumshirn at suse.de>
--
Johannes Thumshirn Storage
jthumshirn at suse.de +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N?rnberg
GF: Felix Imend?rffer, Jane Smithard, Graham Norton
HRB 21284 (AG N?rnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850
next prev parent reply other threads:[~2016-02-18 8:34 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-17 18:03 nvme: remove the global device list and kthread Christoph Hellwig
2016-02-17 18:03 ` [PATCH 1/3] nvme: use a work item to submit async event requests Christoph Hellwig
2016-02-17 18:37 ` Keith Busch
2016-02-18 8:32 ` Johannes Thumshirn
2016-02-22 8:37 ` Sagi Grimberg
2016-02-17 18:03 ` [PATCH 2/3] nvme: don't poll the CQ from the kthread Christoph Hellwig
2016-02-17 18:44 ` Keith Busch
2016-02-18 8:34 ` Johannes Thumshirn [this message]
2016-02-22 8:38 ` Sagi Grimberg
2016-02-17 18:03 ` [PATCH 3/3] nvme: replace the kthread with a per-device watchdog timer Christoph Hellwig
2016-02-17 18:44 ` Keith Busch
2016-02-18 8:36 ` Johannes Thumshirn
2016-02-22 8:43 ` Sagi Grimberg
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