From: Long Li <longli@microsoft.com>
To: Long Li <longli@microsoft.com>, Sasha Levin <sashal@kernel.org>,
"longli@linuxonhyperv.com" <longli@linuxonhyperv.com>
Cc: KY Srinivasan <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
"James E.J. Bottomley" <jejb@linux.ibm.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [Patch v4] storvsc: setup 1:1 mapping between hardware queue and CPU queue
Date: Tue, 24 Sep 2019 01:14:23 +0000 [thread overview]
Message-ID: <CY4PR21MB0741F09608817762DC2CB954CE840@CY4PR21MB0741.namprd21.prod.outlook.com> (raw)
In-Reply-To: <CY4PR21MB0741A256EEF9D8DBAF50ED03CEBA0@CY4PR21MB0741.namprd21.prod.outlook.com>
>Subject: RE: [Patch v4] storvsc: setup 1:1 mapping between hardware queue
>and CPU queue
>
>>Subject: Re: [Patch v4] storvsc: setup 1:1 mapping between hardware
>>queue and CPU queue
>>
>>On Fri, Sep 06, 2019 at 10:24:20AM -0700, longli@linuxonhyperv.com wrote:
>>>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>
Hi Martin,
I have addressed all comments on this patch. Can you merge it to SCSI?
If there is anything else I need to change, please let me know.
Thanks
Long
>>>---
>>>
>>>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();
>>
>>Just looking at the change notes for v3: why isn't this
>>num_active_cpus() then? One can still isolate CPUs on hyper-v, no?
>
>The isolated CPU can be made online at run time. For example, even
>maxcpus=x is put on the boot line, individual CPUs can still be made
>online/offline.
>
>>
>>--
>>Thanks,
>>Sasha
next prev parent reply other threads:[~2019-09-24 1:15 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-06 17:24 [Patch v4] storvsc: setup 1:1 mapping between hardware queue and CPU queue longli
2019-09-06 19:14 ` Michael Kelley
2019-09-06 20:08 ` Sasha Levin
2019-09-06 21:37 ` Long Li
2019-09-24 1:14 ` Long Li [this message]
2019-09-24 2:53 ` Martin K. Petersen
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