* [Patch v4] storvsc: setup 1:1 mapping between hardware queue and CPU queue
@ 2019-09-06 17:24 longli
2019-09-06 19:14 ` Michael Kelley
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: longli @ 2019-09-06 17:24 UTC (permalink / raw)
To: K. Y. Srinivasan, Haiyang Zhang, Stephen Hemminger, Sasha Levin,
James E.J. Bottomley, Martin K. Petersen, linux-hyperv,
linux-scsi, linux-kernel
Cc: Long Li
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
^ permalink raw reply related [flat|nested] 6+ messages in thread
* RE: [Patch v4] storvsc: setup 1:1 mapping between hardware queue and CPU queue
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
2019-09-24 2:53 ` Martin K. Petersen
2 siblings, 0 replies; 6+ messages in thread
From: Michael Kelley @ 2019-09-06 19:14 UTC (permalink / raw)
To: longli, KY Srinivasan, Haiyang Zhang, Stephen Hemminger,
Sasha Levin, James E.J. Bottomley, Martin K. Petersen,
linux-hyperv, linux-scsi, linux-kernel
Cc: Long Li
From: Long Li <longli@microsoft.com> Sent: Friday, September 6, 2019 10:24 AM
>
> 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
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Patch v4] storvsc: setup 1:1 mapping between hardware queue and CPU queue
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 2:53 ` Martin K. Petersen
2 siblings, 1 reply; 6+ messages in thread
From: Sasha Levin @ 2019-09-06 20:08 UTC (permalink / raw)
To: longli
Cc: K. Y. Srinivasan, Haiyang Zhang, Stephen Hemminger,
James E.J. Bottomley, Martin K. Petersen, linux-hyperv,
linux-scsi, linux-kernel, Long Li
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>
>---
>
>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?
--
Thanks,
Sasha
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: [Patch v4] storvsc: setup 1:1 mapping between hardware queue and CPU queue
2019-09-06 20:08 ` Sasha Levin
@ 2019-09-06 21:37 ` Long Li
2019-09-24 1:14 ` Long Li
0 siblings, 1 reply; 6+ messages in thread
From: Long Li @ 2019-09-06 21:37 UTC (permalink / raw)
To: Sasha Levin, longli
Cc: KY Srinivasan, Haiyang Zhang, Stephen Hemminger,
James E.J. Bottomley, Martin K. Petersen, linux-hyperv,
linux-scsi, linux-kernel
>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>
>>---
>>
>>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
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: [Patch v4] storvsc: setup 1:1 mapping between hardware queue and CPU queue
2019-09-06 21:37 ` Long Li
@ 2019-09-24 1:14 ` Long Li
0 siblings, 0 replies; 6+ messages in thread
From: Long Li @ 2019-09-24 1:14 UTC (permalink / raw)
To: Long Li, Sasha Levin, longli
Cc: KY Srinivasan, Haiyang Zhang, Stephen Hemminger,
James E.J. Bottomley, Martin K. Petersen, linux-hyperv,
linux-scsi, linux-kernel
>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
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Patch v4] storvsc: setup 1:1 mapping between hardware queue and CPU queue
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
@ 2019-09-24 2:53 ` Martin K. Petersen
2 siblings, 0 replies; 6+ messages in thread
From: Martin K. Petersen @ 2019-09-24 2:53 UTC (permalink / raw)
To: longli
Cc: K. Y. Srinivasan, Haiyang Zhang, Stephen Hemminger, Sasha Levin,
James E.J. Bottomley, Martin K. Petersen, linux-hyperv,
linux-scsi, linux-kernel, Long Li
Long,
> 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.
Applied to 5.4/scsi-fixes. Thanks!
--
Martin K. Petersen Oracle Linux Engineering
^ permalink raw reply [flat|nested] 6+ messages in thread
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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
2019-09-24 2:53 ` Martin K. Petersen
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