[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20240620065641.GA22113@lst.de>
Date: Thu, 20 Jun 2024 08:56:41 +0200
From: Christoph Hellwig <hch@....de>
To: John Meneghini <jmeneghi@...hat.com>
Cc: kbusch@...nel.org, hch@....de, sagi@...mberg.me,
linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org,
emilne@...hat.com, jrani@...estorage.com, randyj@...estorage.com,
chaitanyak@...dia.com, hare@...nel.org
Subject: Re: [PATCH v7 1/1] nvme-multipath: implement "queue-depth" iopolicy
> [jmeneghi: vairious changes and improvements, addressed review comments]
s/vairious/various/
> + if ((nvme_req(rq)->flags & NVME_MPATH_CNT_ACTIVE))
No need for the double braces here.
> + WARN_ON_ONCE((atomic_dec_if_positive(&ns->ctrl->nr_active)) < 0);
Overly long line.
But I don't understand why you need the WARN_ON anyway. If the value
must always be positive there is no point in atomic_dec_if_positive.
If misaccounting is fine there WARN_ON is counterproductive.
> -static struct nvme_ns *nvme_round_robin_path(struct nvme_ns_head *head,
> - int node, struct nvme_ns *old)
> +static struct nvme_ns *nvme_round_robin_path(struct nvme_ns_head *head)
> {
> - struct nvme_ns *ns, *found = NULL;
> + struct nvme_ns *ns, *old, *found = NULL;
> + int node = numa_node_id();
> +
> + old = srcu_dereference(head->current_path[node], &head->srcu);
> + if (unlikely(!old))
> + return __nvme_find_path(head, node);
Can you split the refactoring of the existing path selectors into a
prep patch, please?
> +static void nvme_subsys_iopolicy_update(struct nvme_subsystem *subsys,
> + int iopolicy)
> +{
> + struct nvme_ctrl *ctrl;
> + int old_iopolicy = READ_ONCE(subsys->iopolicy);
> +
> + if (old_iopolicy == iopolicy)
> + return;
> +
> + WRITE_ONCE(subsys->iopolicy, iopolicy);
What is the atomicy model here? There doesn't seem to be any
global lock protecting it? Maybe move it into the
nvme_subsystems_lock critical section?
> + pr_notice("%s: changed from %s to %s for subsysnqn %s\n", __func__,
> + nvme_iopolicy_names[old_iopolicy], nvme_iopolicy_names[iopolicy],
> + subsys->subnqn);
The function is not really relevant here, this should become something
like:
pr_notice("%s: changing iopolicy from %s to %s\n",
subsys->subnqn,
nvme_iopolicy_names[old_iopolicy],
nvme_iopolicy_names[iopolicy]);
or maybe:
dev_notice(changing iopolicy from %s to %s\n",
&subsys->dev,
nvme_iopolicy_names[old_iopolicy],
nvme_iopolicy_names[iopolicy]);
Powered by blists - more mailing lists