Re: [PATCH 1/1] scsi: storvsc: Spread interrupts when picking a channel for I/O requests

2018-02-06 Thread Martin K. Petersen 

Michael,

> Update the algorithm in storvsc_do_io to look for a channel starting
> with the current CPU + 1 and wrap around (within the current NUMA
> node). This spreads VMbus interrupts more evenly across CPUs. Previous
> code always started with first CPU in the current NUMA node, skewing
> the interrupt load to that CPU.

Applied to 4.16/scsi-fixes. Thanks!

-- 
Martin K. Petersen  Oracle Linux Engineering

RE: [PATCH 1/1] scsi: storvsc: Spread interrupts when picking a channel for I/O requests

2018-01-31 Thread Long Li 
> Subject: RE: [PATCH 1/1] scsi: storvsc: Spread interrupts when picking a
> channel for I/O requests
> 
> > From: Long Li
> > Sent: Wednesday, January 31, 2018 12:23 PM
> > To: Michael Kelley (EOSG) <michael.h.kel...@microsoft.com>; KY
> > Srinivasan <k...@microsoft.com>; Stephen Hemminger
> > <sthem...@microsoft.com>; martin.peter...@oracle.com;
> > de...@linuxdriverproject.org; linux-ker...@vger.kernel.org;
> > linux-scsi@vger.kernel.org; James E . J . Bottomley
> > <j...@linux.vnet.ibm.com>
> > Subject: RE: [PATCH 1/1] scsi: storvsc: Spread interrupts when picking
> > a channel for I/O requests
> >
> > > Subject: RE: [PATCH 1/1] scsi: storvsc: Spread interrupts when
> > > picking a channel for I/O requests
> > >
> > > Updated/corrected two email addresses ...
> > >
> > > > -Original Message-
> > > > From: Michael Kelley (EOSG)
> > > > Sent: Wednesday, January 24, 2018 2:14 PM
> > > > To: KY Srinivasan <k...@microsoft.com>; Stephen Hemminger
> > > > <sthem...@microsoft.com>; martin.peter...@oracle.com;
> > > > lo...@microsoft.com; jbottom...@odin.com;
> > > > de...@linuxdriverproject.org; linux-ker...@vger.kernel.org;
> > > > linux-scsi@vger.kernel.org
> > > > Cc: Michael Kelley (EOSG) <michael.h.kel...@microsoft.com>
> > > > Subject: [PATCH 1/1] scsi: storvsc: Spread interrupts when picking
> > > > a channel for I/O requests
> > > >
> > > > Update the algorithm in storvsc_do_io to look for a channel
> > > > starting with the current CPU + 1 and wrap around (within the
> > > > current NUMA node). This spreads VMbus interrupts more evenly
> > > > across CPUs. Previous code always started with first CPU in the
> > > > current NUMA node, skewing the interrupt load to that CPU.
> > > >
> > > > Signed-off-by: Michael Kelley <mikel...@microsoft.com>

Reviewed-by: Long Li <lon...@microsoft.com>

> > > > ---
> > > >  drivers/scsi/storvsc_drv.c | 3 ++-
> > > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/scsi/storvsc_drv.c
> > > > b/drivers/scsi/storvsc_drv.c index e07907d..f3264c4 100644
> > > > --- a/drivers/scsi/storvsc_drv.c
> > > > +++ b/drivers/scsi/storvsc_drv.c
> > > > @@ -1310,7 +1310,8 @@ static int storvsc_do_io(struct hv_device
> *device,
> > > >  */
> > > > cpumask_and(_mask, _device-
> alloced_cpus,
> > > >
> > > cpumask_of_node(cpu_to_node(q_num)));
> > > > -   for_each_cpu(tgt_cpu, _mask) {
> > > > +   for_each_cpu_wrap(tgt_cpu, _mask,
> > > > +   outgoing_channel->target_cpu + 
> > > > 1) {
> >
> > Does it work when target_cpu is the last CPU on the system?
> >
> > Otherwise, looking good.
> 
> Yes, it works.  for_each_cpu_wrap() correctly wraps in the case where the
> 3rd parameter ('start') is one past the end of the mask.  Arguably, we
> shouldn't rely on that, and should do the wrap to 0 before calling
> for_each_cpu_wrap().
> 
> >
> > > > if (tgt_cpu != 
> > > > outgoing_channel->target_cpu)
> > > {
> > > > outgoing_channel =
> > > > stor_device->stor_chns[tgt_cpu];
> > > > --
> > > > 1.8.3.1

RE: [PATCH 1/1] scsi: storvsc: Spread interrupts when picking a channel for I/O requests

2018-01-31 Thread Michael Kelley (EOSG) 
> From: Long Li
> Sent: Wednesday, January 31, 2018 12:23 PM
> To: Michael Kelley (EOSG) <michael.h.kel...@microsoft.com>; KY Srinivasan
> <k...@microsoft.com>; Stephen Hemminger <sthem...@microsoft.com>;
> martin.peter...@oracle.com; de...@linuxdriverproject.org; 
> linux-ker...@vger.kernel.org;
> linux-scsi@vger.kernel.org; James E . J . Bottomley <j...@linux.vnet.ibm.com>
> Subject: RE: [PATCH 1/1] scsi: storvsc: Spread interrupts when picking a 
> channel for I/O
> requests
> 
> > Subject: RE: [PATCH 1/1] scsi: storvsc: Spread interrupts when picking a
> > channel for I/O requests
> >
> > Updated/corrected two email addresses ...
> >
> > > -Original Message-
> > > From: Michael Kelley (EOSG)
> > > Sent: Wednesday, January 24, 2018 2:14 PM
> > > To: KY Srinivasan <k...@microsoft.com>; Stephen Hemminger
> > > <sthem...@microsoft.com>; martin.peter...@oracle.com;
> > > lo...@microsoft.com; jbottom...@odin.com;
> > > de...@linuxdriverproject.org; linux-ker...@vger.kernel.org;
> > > linux-scsi@vger.kernel.org
> > > Cc: Michael Kelley (EOSG) <michael.h.kel...@microsoft.com>
> > > Subject: [PATCH 1/1] scsi: storvsc: Spread interrupts when picking a
> > > channel for I/O requests
> > >
> > > Update the algorithm in storvsc_do_io to look for a channel starting
> > > with the current CPU + 1 and wrap around (within the current NUMA
> > > node). This spreads VMbus interrupts more evenly across CPUs. Previous
> > > code always started with first CPU in the current NUMA node, skewing
> > > the interrupt load to that CPU.
> > >
> > > Signed-off-by: Michael Kelley <mikel...@microsoft.com>
> > > ---
> > >  drivers/scsi/storvsc_drv.c | 3 ++-
> > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
> > > index e07907d..f3264c4 100644
> > > --- a/drivers/scsi/storvsc_drv.c
> > > +++ b/drivers/scsi/storvsc_drv.c
> > > @@ -1310,7 +1310,8 @@ static int storvsc_do_io(struct hv_device *device,
> > >*/
> > >   cpumask_and(_mask, _device-
> > >alloced_cpus,
> > >
> > cpumask_of_node(cpu_to_node(q_num)));
> > > - for_each_cpu(tgt_cpu, _mask) {
> > > + for_each_cpu_wrap(tgt_cpu, _mask,
> > > + outgoing_channel->target_cpu + 1) {
> 
> Does it work when target_cpu is the last CPU on the system?
> 
> Otherwise, looking good.

Yes, it works.  for_each_cpu_wrap() correctly wraps in the case where
the 3rd parameter ('start') is one past the end of the mask.  Arguably,
we shouldn't rely on that, and should do the wrap to 0 before calling
for_each_cpu_wrap().

> 
> > >   if (tgt_cpu != outgoing_channel->target_cpu)
> > {
> > >   outgoing_channel =
> > >   stor_device->stor_chns[tgt_cpu];
> > > --
> > > 1.8.3.1

RE: [PATCH 1/1] scsi: storvsc: Spread interrupts when picking a channel for I/O requests

2018-01-31 Thread Long Li 
> Subject: RE: [PATCH 1/1] scsi: storvsc: Spread interrupts when picking a
> channel for I/O requests
> 
> Updated/corrected two email addresses ...
> 
> > -Original Message-
> > From: Michael Kelley (EOSG)
> > Sent: Wednesday, January 24, 2018 2:14 PM
> > To: KY Srinivasan <k...@microsoft.com>; Stephen Hemminger
> > <sthem...@microsoft.com>; martin.peter...@oracle.com;
> > lo...@microsoft.com; jbottom...@odin.com;
> > de...@linuxdriverproject.org; linux-ker...@vger.kernel.org;
> > linux-scsi@vger.kernel.org
> > Cc: Michael Kelley (EOSG) <michael.h.kel...@microsoft.com>
> > Subject: [PATCH 1/1] scsi: storvsc: Spread interrupts when picking a
> > channel for I/O requests
> >
> > Update the algorithm in storvsc_do_io to look for a channel starting
> > with the current CPU + 1 and wrap around (within the current NUMA
> > node). This spreads VMbus interrupts more evenly across CPUs. Previous
> > code always started with first CPU in the current NUMA node, skewing
> > the interrupt load to that CPU.
> >
> > Signed-off-by: Michael Kelley <mikel...@microsoft.com>
> > ---
> >  drivers/scsi/storvsc_drv.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
> > index e07907d..f3264c4 100644
> > --- a/drivers/scsi/storvsc_drv.c
> > +++ b/drivers/scsi/storvsc_drv.c
> > @@ -1310,7 +1310,8 @@ static int storvsc_do_io(struct hv_device *device,
> >  */
> > cpumask_and(_mask, _device-
> >alloced_cpus,
> >
> cpumask_of_node(cpu_to_node(q_num)));
> > -   for_each_cpu(tgt_cpu, _mask) {
> > +   for_each_cpu_wrap(tgt_cpu, _mask,
> > +   outgoing_channel->target_cpu + 1) {

Does it work when target_cpu is the last CPU on the system?

Otherwise, looking good.

> > if (tgt_cpu != outgoing_channel->target_cpu)
> {
> > outgoing_channel =
> > stor_device->stor_chns[tgt_cpu];
> > --
> > 1.8.3.1

RE: [PATCH 1/1] scsi: storvsc: Spread interrupts when picking a channel for I/O requests

2018-01-24 Thread Michael Kelley (EOSG) 
Updated/corrected two email addresses ...

> -Original Message-
> From: Michael Kelley (EOSG)
> Sent: Wednesday, January 24, 2018 2:14 PM
> To: KY Srinivasan <k...@microsoft.com>; Stephen Hemminger 
> <sthem...@microsoft.com>;
> martin.peter...@oracle.com; lo...@microsoft.com; jbottom...@odin.com;
> de...@linuxdriverproject.org; linux-ker...@vger.kernel.org; 
> linux-scsi@vger.kernel.org
> Cc: Michael Kelley (EOSG) <michael.h.kel...@microsoft.com>
> Subject: [PATCH 1/1] scsi: storvsc: Spread interrupts when picking a channel 
> for I/O requests
> 
> Update the algorithm in storvsc_do_io to look for a channel
> starting with the current CPU + 1 and wrap around (within the
> current NUMA node). This spreads VMbus interrupts more evenly
> across CPUs. Previous code always started with first CPU in
> the current NUMA node, skewing the interrupt load to that CPU.
> 
> Signed-off-by: Michael Kelley <mikel...@microsoft.com>
> ---
>  drivers/scsi/storvsc_drv.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
> index e07907d..f3264c4 100644
> --- a/drivers/scsi/storvsc_drv.c
> +++ b/drivers/scsi/storvsc_drv.c
> @@ -1310,7 +1310,8 @@ static int storvsc_do_io(struct hv_device *device,
>*/
>   cpumask_and(_mask, _device->alloced_cpus,
>   cpumask_of_node(cpu_to_node(q_num)));
> - for_each_cpu(tgt_cpu, _mask) {
> + for_each_cpu_wrap(tgt_cpu, _mask,
> + outgoing_channel->target_cpu + 1) {
>   if (tgt_cpu != outgoing_channel->target_cpu) {
>   outgoing_channel =
>   stor_device->stor_chns[tgt_cpu];
> --
> 1.8.3.1

[PATCH 1/1] scsi: storvsc: Spread interrupts when picking a channel for I/O requests

2018-01-24 Thread Michael Kelley (EOSG) 
Update the algorithm in storvsc_do_io to look for a channel
starting with the current CPU + 1 and wrap around (within the
current NUMA node). This spreads VMbus interrupts more evenly
across CPUs. Previous code always started with first CPU in
the current NUMA node, skewing the interrupt load to that CPU.

Signed-off-by: Michael Kelley 
---
 drivers/scsi/storvsc_drv.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index e07907d..f3264c4 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1310,7 +1310,8 @@ static int storvsc_do_io(struct hv_device *device,
 */
cpumask_and(_mask, _device->alloced_cpus,
cpumask_of_node(cpu_to_node(q_num)));
-   for_each_cpu(tgt_cpu, _mask) {
+   for_each_cpu_wrap(tgt_cpu, _mask,
+   outgoing_channel->target_cpu + 1) {
if (tgt_cpu != outgoing_channel->target_cpu) {
outgoing_channel =
stor_device->stor_chns[tgt_cpu];
-- 
1.8.3.1