From: longli@linuxonhyperv.com
To: "K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Sasha Levin <sashal@kernel.org>,
"James E.J. Bottomley" <jejb@linux.ibm.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
linux-hyperv@vger.kernel.org, linux-scsi@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: Long Li <longli@microsoft.com>
Subject: [Patch v4] storvsc: setup 1:1 mapping between hardware queue and CPU queue
Date: Fri, 6 Sep 2019 10:24:20 -0700 [thread overview]
Message-ID: <1567790660-48142-1-git-send-email-longli@linuxonhyperv.com> (raw)
From: Long Li <longli@microsoft.com>
storvsc doesn't use a dedicated hardware queue for a given CPU queue. When
issuing I/O, it selects returning CPU (hardware queue) dynamically based on
vmbus channel usage across all channels.
This patch advertises num_present_cpus() as number of hardware queues. This
will have upper layer setup 1:1 mapping between hardware queue and CPU queue
and avoid unnecessary locking when issuing I/O.
Signed-off-by: Long Li <longli@microsoft.com>
---
Changes:
v2: rely on default upper layer function to map queues. (suggested by Ming Lei
<tom.leiming@gmail.com>)
v3: use num_present_cpus() instead of num_online_cpus(). Hyper-v doesn't
support hot-add CPUs. (suggested by Michael Kelley <mikelley@microsoft.com>)
v4: move change logs to after Signed-of-by
drivers/scsi/storvsc_drv.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index b89269120a2d..cf987712041a 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1836,8 +1836,7 @@ static int storvsc_probe(struct hv_device *device,
/*
* Set the number of HW queues we are supporting.
*/
- if (stor_device->num_sc != 0)
- host->nr_hw_queues = stor_device->num_sc + 1;
+ host->nr_hw_queues = num_present_cpus();
/*
* Set the error handler work queue.
--
2.17.1
next reply other threads:[~2019-09-06 17:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-06 17:24 longli [this message]
2019-09-06 19:14 ` [Patch v4] storvsc: setup 1:1 mapping between hardware queue and CPU queue Michael Kelley
2019-09-06 20:08 ` Sasha Levin
2019-09-06 21:37 ` Long Li
2019-09-24 1:14 ` Long Li
2019-09-24 2:53 ` Martin K. Petersen
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