From: Tao Ren <[email protected]>
This patch evaluates vhub ports' irq mask before going through per-port
irq handling one by one, which helps to speed up irq handling in case
there is no port interrupt.
Signed-off-by: Tao Ren <[email protected]>
---
Changes in v3:
- assign istat to (unsigned long) bitmap before calling
"for_each_set_bit_from".
Changes in v2:
- use "for_each_set_bit" to speed up port irq handling.
drivers/usb/gadget/udc/aspeed-vhub/core.c | 12 +++++++++---
drivers/usb/gadget/udc/aspeed-vhub/vhub.h | 8 +++-----
2 files changed, 12 insertions(+), 8 deletions(-)
diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
index f8d35dd60c34..555e8645fb1e 100644
--- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
+++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
@@ -134,11 +134,15 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
}
/* Handle device interrupts */
- for (i = 0; i < vhub->max_ports; i++) {
- u32 dev_mask = VHUB_IRQ_DEVICE1 << i;
+ if (istat & vhub->port_irq_mask) {
+ unsigned long bitmap = istat;
+ int offset = VHUB_IRQ_DEV1_BIT;
+ int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
- if (istat & dev_mask)
+ for_each_set_bit_from(offset, &bitmap, size) {
+ i = offset - VHUB_IRQ_DEV1_BIT;
ast_vhub_dev_irq(&vhub->ports[i].dev);
+ }
}
/* Handle top-level vHub EP0 interrupts */
@@ -332,6 +336,8 @@ static int ast_vhub_probe(struct platform_device *pdev)
spin_lock_init(&vhub->lock);
vhub->pdev = pdev;
+ vhub->port_irq_mask = GENMASK(VHUB_IRQ_DEV1_BIT + vhub->max_ports - 1,
+ VHUB_IRQ_DEV1_BIT);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
vhub->regs = devm_ioremap_resource(&pdev->dev, res);
diff --git a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
index fac79ef6d669..23a1ac91f8d2 100644
--- a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
+++ b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
@@ -51,14 +51,11 @@
#define VHUB_CTRL_UPSTREAM_CONNECT (1 << 0)
/* IER & ISR */
+#define VHUB_IRQ_DEV1_BIT 9
#define VHUB_IRQ_USB_CMD_DEADLOCK (1 << 18)
#define VHUB_IRQ_EP_POOL_NAK (1 << 17)
#define VHUB_IRQ_EP_POOL_ACK_STALL (1 << 16)
-#define VHUB_IRQ_DEVICE5 (1 << 13)
-#define VHUB_IRQ_DEVICE4 (1 << 12)
-#define VHUB_IRQ_DEVICE3 (1 << 11)
-#define VHUB_IRQ_DEVICE2 (1 << 10)
-#define VHUB_IRQ_DEVICE1 (1 << 9)
+#define VHUB_IRQ_DEVICE1 (1 << (VHUB_IRQ_DEV1_BIT))
#define VHUB_IRQ_BUS_RESUME (1 << 8)
#define VHUB_IRQ_BUS_SUSPEND (1 << 7)
#define VHUB_IRQ_BUS_RESET (1 << 6)
@@ -402,6 +399,7 @@ struct ast_vhub {
/* Per-port info */
struct ast_vhub_port *ports;
u32 max_ports;
+ u32 port_irq_mask;
/* Generic EP data structures */
struct ast_vhub_ep *epns;
--
2.17.1
Hi Ben,
Any further comments on the patch?
Cheers,
Tao
On Sun, Mar 15, 2020 at 12:14:30PM -0700, [email protected] wrote:
> From: Tao Ren <[email protected]>
>
> This patch evaluates vhub ports' irq mask before going through per-port
> irq handling one by one, which helps to speed up irq handling in case
> there is no port interrupt.
>
> Signed-off-by: Tao Ren <[email protected]>
> ---
> Changes in v3:
> - assign istat to (unsigned long) bitmap before calling
> "for_each_set_bit_from".
> Changes in v2:
> - use "for_each_set_bit" to speed up port irq handling.
>
> drivers/usb/gadget/udc/aspeed-vhub/core.c | 12 +++++++++---
> drivers/usb/gadget/udc/aspeed-vhub/vhub.h | 8 +++-----
> 2 files changed, 12 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> index f8d35dd60c34..555e8645fb1e 100644
> --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
> +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> @@ -134,11 +134,15 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
> }
>
> /* Handle device interrupts */
> - for (i = 0; i < vhub->max_ports; i++) {
> - u32 dev_mask = VHUB_IRQ_DEVICE1 << i;
> + if (istat & vhub->port_irq_mask) {
> + unsigned long bitmap = istat;
> + int offset = VHUB_IRQ_DEV1_BIT;
> + int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
>
> - if (istat & dev_mask)
> + for_each_set_bit_from(offset, &bitmap, size) {
> + i = offset - VHUB_IRQ_DEV1_BIT;
> ast_vhub_dev_irq(&vhub->ports[i].dev);
> + }
> }
>
> /* Handle top-level vHub EP0 interrupts */
> @@ -332,6 +336,8 @@ static int ast_vhub_probe(struct platform_device *pdev)
>
> spin_lock_init(&vhub->lock);
> vhub->pdev = pdev;
> + vhub->port_irq_mask = GENMASK(VHUB_IRQ_DEV1_BIT + vhub->max_ports - 1,
> + VHUB_IRQ_DEV1_BIT);
>
> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> vhub->regs = devm_ioremap_resource(&pdev->dev, res);
> diff --git a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> index fac79ef6d669..23a1ac91f8d2 100644
> --- a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> +++ b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> @@ -51,14 +51,11 @@
> #define VHUB_CTRL_UPSTREAM_CONNECT (1 << 0)
>
> /* IER & ISR */
> +#define VHUB_IRQ_DEV1_BIT 9
> #define VHUB_IRQ_USB_CMD_DEADLOCK (1 << 18)
> #define VHUB_IRQ_EP_POOL_NAK (1 << 17)
> #define VHUB_IRQ_EP_POOL_ACK_STALL (1 << 16)
> -#define VHUB_IRQ_DEVICE5 (1 << 13)
> -#define VHUB_IRQ_DEVICE4 (1 << 12)
> -#define VHUB_IRQ_DEVICE3 (1 << 11)
> -#define VHUB_IRQ_DEVICE2 (1 << 10)
> -#define VHUB_IRQ_DEVICE1 (1 << 9)
> +#define VHUB_IRQ_DEVICE1 (1 << (VHUB_IRQ_DEV1_BIT))
> #define VHUB_IRQ_BUS_RESUME (1 << 8)
> #define VHUB_IRQ_BUS_SUSPEND (1 << 7)
> #define VHUB_IRQ_BUS_RESET (1 << 6)
> @@ -402,6 +399,7 @@ struct ast_vhub {
> /* Per-port info */
> struct ast_vhub_port *ports;
> u32 max_ports;
> + u32 port_irq_mask;
>
> /* Generic EP data structures */
> struct ast_vhub_ep *epns;
> --
> 2.17.1
>
On Wed, 2020-04-01 at 14:58 -0700, Tao Ren wrote:
> Hi Ben,
>
> Any further comments on the patch?
Ah sorry, nope. Did you check the generated assembly to see if it
looked any better ? :-)
Otherwise,
Acked-by: Benjamin Herrenschmidt <[email protected]>
>
> Cheers,
>
> Tao
>
> On Sun, Mar 15, 2020 at 12:14:30PM -0700, [email protected]
> wrote:
> > From: Tao Ren <[email protected]>
> >
> > This patch evaluates vhub ports' irq mask before going through per-
> > port
> > irq handling one by one, which helps to speed up irq handling in
> > case
> > there is no port interrupt.
> >
> > Signed-off-by: Tao Ren <[email protected]>
> > ---
> > Changes in v3:
> > - assign istat to (unsigned long) bitmap before calling
> > "for_each_set_bit_from".
> > Changes in v2:
> > - use "for_each_set_bit" to speed up port irq handling.
> >
> > drivers/usb/gadget/udc/aspeed-vhub/core.c | 12 +++++++++---
> > drivers/usb/gadget/udc/aspeed-vhub/vhub.h | 8 +++-----
> > 2 files changed, 12 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > index f8d35dd60c34..555e8645fb1e 100644
> > --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > @@ -134,11 +134,15 @@ static irqreturn_t ast_vhub_irq(int irq, void
> > *data)
> > }
> >
> > /* Handle device interrupts */
> > - for (i = 0; i < vhub->max_ports; i++) {
> > - u32 dev_mask = VHUB_IRQ_DEVICE1 << i;
> > + if (istat & vhub->port_irq_mask) {
> > + unsigned long bitmap = istat;
> > + int offset = VHUB_IRQ_DEV1_BIT;
> > + int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
> >
> > - if (istat & dev_mask)
> > + for_each_set_bit_from(offset, &bitmap, size) {
> > + i = offset - VHUB_IRQ_DEV1_BIT;
> > ast_vhub_dev_irq(&vhub->ports[i].dev);
> > + }
> > }
> >
> > /* Handle top-level vHub EP0 interrupts */
> > @@ -332,6 +336,8 @@ static int ast_vhub_probe(struct
> > platform_device *pdev)
> >
> > spin_lock_init(&vhub->lock);
> > vhub->pdev = pdev;
> > + vhub->port_irq_mask = GENMASK(VHUB_IRQ_DEV1_BIT + vhub-
> > >max_ports - 1,
> > + VHUB_IRQ_DEV1_BIT);
> >
> > res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > vhub->regs = devm_ioremap_resource(&pdev->dev, res);
> > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> > b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> > index fac79ef6d669..23a1ac91f8d2 100644
> > --- a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> > +++ b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> > @@ -51,14 +51,11 @@
> > #define VHUB_CTRL_UPSTREAM_CONNECT (1 << 0)
> >
> > /* IER & ISR */
> > +#define VHUB_IRQ_DEV1_BIT 9
> > #define VHUB_IRQ_USB_CMD_DEADLOCK (1 << 18)
> > #define VHUB_IRQ_EP_POOL_NAK (1 << 17)
> > #define VHUB_IRQ_EP_POOL_ACK_STALL (1 << 16)
> > -#define VHUB_IRQ_DEVICE5 (1 << 13)
> > -#define VHUB_IRQ_DEVICE4 (1 << 12)
> > -#define VHUB_IRQ_DEVICE3 (1 << 11)
> > -#define VHUB_IRQ_DEVICE2 (1 << 10)
> > -#define VHUB_IRQ_DEVICE1 (1 << 9)
> > +#define VHUB_IRQ_DEVICE1 (1 <<
> > (VHUB_IRQ_DEV1_BIT))
> > #define VHUB_IRQ_BUS_RESUME (1 << 8)
> > #define VHUB_IRQ_BUS_SUSPEND (1 << 7)
> > #define VHUB_IRQ_BUS_RESET (1 << 6)
> > @@ -402,6 +399,7 @@ struct ast_vhub {
> > /* Per-port info */
> > struct ast_vhub_port *ports;
> > u32 max_ports;
> > + u32 port_irq_mask;
> >
> > /* Generic EP data structures */
> > struct ast_vhub_ep *epns;
> > --
> > 2.17.1
> >
On Thu, Apr 02, 2020 at 09:45:38PM +1100, Benjamin Herrenschmidt wrote:
> On Wed, 2020-04-01 at 14:58 -0700, Tao Ren wrote:
> > Hi Ben,
> >
> > Any further comments on the patch?
>
> Ah sorry, nope. Did you check the generated assembly to see if it
> looked any better ? :-)
>
> Otherwise,
>
> Acked-by: Benjamin Herrenschmidt <[email protected]>
Thanks Ben for the review. Let me see if I can collect some runtime data
on my ast2400 BMC platform. Will update back later.
Cheers,
Tao
>
> >
> > Cheers,
> >
> > Tao
> >
> > On Sun, Mar 15, 2020 at 12:14:30PM -0700, [email protected]
> > wrote:
> > > From: Tao Ren <[email protected]>
> > >
> > > This patch evaluates vhub ports' irq mask before going through per-
> > > port
> > > irq handling one by one, which helps to speed up irq handling in
> > > case
> > > there is no port interrupt.
> > >
> > > Signed-off-by: Tao Ren <[email protected]>
> > > ---
> > > Changes in v3:
> > > - assign istat to (unsigned long) bitmap before calling
> > > "for_each_set_bit_from".
> > > Changes in v2:
> > > - use "for_each_set_bit" to speed up port irq handling.
> > >
> > > drivers/usb/gadget/udc/aspeed-vhub/core.c | 12 +++++++++---
> > > drivers/usb/gadget/udc/aspeed-vhub/vhub.h | 8 +++-----
> > > 2 files changed, 12 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > > b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > > index f8d35dd60c34..555e8645fb1e 100644
> > > --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > > +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > > @@ -134,11 +134,15 @@ static irqreturn_t ast_vhub_irq(int irq, void
> > > *data)
> > > }
> > >
> > > /* Handle device interrupts */
> > > - for (i = 0; i < vhub->max_ports; i++) {
> > > - u32 dev_mask = VHUB_IRQ_DEVICE1 << i;
> > > + if (istat & vhub->port_irq_mask) {
> > > + unsigned long bitmap = istat;
> > > + int offset = VHUB_IRQ_DEV1_BIT;
> > > + int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
> > >
> > > - if (istat & dev_mask)
> > > + for_each_set_bit_from(offset, &bitmap, size) {
> > > + i = offset - VHUB_IRQ_DEV1_BIT;
> > > ast_vhub_dev_irq(&vhub->ports[i].dev);
> > > + }
> > > }
> > >
> > > /* Handle top-level vHub EP0 interrupts */
> > > @@ -332,6 +336,8 @@ static int ast_vhub_probe(struct
> > > platform_device *pdev)
> > >
> > > spin_lock_init(&vhub->lock);
> > > vhub->pdev = pdev;
> > > + vhub->port_irq_mask = GENMASK(VHUB_IRQ_DEV1_BIT + vhub-
> > > >max_ports - 1,
> > > + VHUB_IRQ_DEV1_BIT);
> > >
> > > res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > > vhub->regs = devm_ioremap_resource(&pdev->dev, res);
> > > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> > > b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> > > index fac79ef6d669..23a1ac91f8d2 100644
> > > --- a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> > > +++ b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> > > @@ -51,14 +51,11 @@
> > > #define VHUB_CTRL_UPSTREAM_CONNECT (1 << 0)
> > >
> > > /* IER & ISR */
> > > +#define VHUB_IRQ_DEV1_BIT 9
> > > #define VHUB_IRQ_USB_CMD_DEADLOCK (1 << 18)
> > > #define VHUB_IRQ_EP_POOL_NAK (1 << 17)
> > > #define VHUB_IRQ_EP_POOL_ACK_STALL (1 << 16)
> > > -#define VHUB_IRQ_DEVICE5 (1 << 13)
> > > -#define VHUB_IRQ_DEVICE4 (1 << 12)
> > > -#define VHUB_IRQ_DEVICE3 (1 << 11)
> > > -#define VHUB_IRQ_DEVICE2 (1 << 10)
> > > -#define VHUB_IRQ_DEVICE1 (1 << 9)
> > > +#define VHUB_IRQ_DEVICE1 (1 <<
> > > (VHUB_IRQ_DEV1_BIT))
> > > #define VHUB_IRQ_BUS_RESUME (1 << 8)
> > > #define VHUB_IRQ_BUS_SUSPEND (1 << 7)
> > > #define VHUB_IRQ_BUS_RESET (1 << 6)
> > > @@ -402,6 +399,7 @@ struct ast_vhub {
> > > /* Per-port info */
> > > struct ast_vhub_port *ports;
> > > u32 max_ports;
> > > + u32 port_irq_mask;
> > >
> > > /* Generic EP data structures */
> > > struct ast_vhub_ep *epns;
> > > --
> > > 2.17.1
> > >
>
Hi Ben,
On Thu, Apr 02, 2020 at 11:48:27PM -0700, Tao Ren wrote:
> On Thu, Apr 02, 2020 at 09:45:38PM +1100, Benjamin Herrenschmidt wrote:
> > On Wed, 2020-04-01 at 14:58 -0700, Tao Ren wrote:
> > > Hi Ben,
> > >
> > > Any further comments on the patch?
> >
> > Ah sorry, nope. Did you check the generated assembly to see if it
> > looked any better ? :-)
> >
> > Otherwise,
> >
> > Acked-by: Benjamin Herrenschmidt <[email protected]>
>
> Thanks Ben for the review. Let me see if I can collect some runtime data
> on my ast2400 BMC platform. Will update back later.
I ran some testing on my ast2400 and ast2500 BMC and looks like the
for() loop runs faster than for_each_set_bit_from() loop in my
environment. I'm not sure if something needs to be revised in my test
code, but please kindly share your suggestions:
I use get_cycles() to calculate execution time of 2 different loops, and
ast_vhub_dev_irq() is replaced with barrier() to avoid "noise"; below
are the results:
- when downstream port number is 5 and only 1 irq bit is set, it takes
~30 cycles to finish for_each_set_bit() loop, and 20-25 cycles to
finish the for() loop.
- if downstream port number is 5 and all 5 bits are set, then
for_each_set_bit() loop takes ~50 cycles and for() loop takes ~25
cycles.
- when I increase downsteam port number to 16 and set 1 irq bit, the
for_each_set_bit() loop takes ~30 cycles and for() loop takes 25
cycles. It's a little surprise to me because I thought for() loop
would cost 60+ cycles (3 times of the value when port number is 5).
- if downstream port number is 16 and all irq status bits are set,
then for_each_set_bit() loop takes 60-70 cycles and for() loop takes
30+ cycles.
Cheers,
Tao
>
> > >
> > > On Sun, Mar 15, 2020 at 12:14:30PM -0700, [email protected]
> > > wrote:
> > > > From: Tao Ren <[email protected]>
> > > >
> > > > This patch evaluates vhub ports' irq mask before going through per-
> > > > port
> > > > irq handling one by one, which helps to speed up irq handling in
> > > > case
> > > > there is no port interrupt.
> > > >
> > > > Signed-off-by: Tao Ren <[email protected]>
> > > > ---
> > > > Changes in v3:
> > > > - assign istat to (unsigned long) bitmap before calling
> > > > "for_each_set_bit_from".
> > > > Changes in v2:
> > > > - use "for_each_set_bit" to speed up port irq handling.
> > > >
> > > > drivers/usb/gadget/udc/aspeed-vhub/core.c | 12 +++++++++---
> > > > drivers/usb/gadget/udc/aspeed-vhub/vhub.h | 8 +++-----
> > > > 2 files changed, 12 insertions(+), 8 deletions(-)
> > > >
> > > > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > > > b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > > > index f8d35dd60c34..555e8645fb1e 100644
> > > > --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > > > +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > > > @@ -134,11 +134,15 @@ static irqreturn_t ast_vhub_irq(int irq, void
> > > > *data)
> > > > }
> > > >
> > > > /* Handle device interrupts */
> > > > - for (i = 0; i < vhub->max_ports; i++) {
> > > > - u32 dev_mask = VHUB_IRQ_DEVICE1 << i;
> > > > + if (istat & vhub->port_irq_mask) {
> > > > + unsigned long bitmap = istat;
> > > > + int offset = VHUB_IRQ_DEV1_BIT;
> > > > + int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
> > > >
> > > > - if (istat & dev_mask)
> > > > + for_each_set_bit_from(offset, &bitmap, size) {
> > > > + i = offset - VHUB_IRQ_DEV1_BIT;
> > > > ast_vhub_dev_irq(&vhub->ports[i].dev);
> > > > + }
> > > > }
> > > >
> > > > /* Handle top-level vHub EP0 interrupts */
> > > > @@ -332,6 +336,8 @@ static int ast_vhub_probe(struct
> > > > platform_device *pdev)
> > > >
> > > > spin_lock_init(&vhub->lock);
> > > > vhub->pdev = pdev;
> > > > + vhub->port_irq_mask = GENMASK(VHUB_IRQ_DEV1_BIT + vhub-
> > > > >max_ports - 1,
> > > > + VHUB_IRQ_DEV1_BIT);
> > > >
> > > > res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > > > vhub->regs = devm_ioremap_resource(&pdev->dev, res);
> > > > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> > > > b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> > > > index fac79ef6d669..23a1ac91f8d2 100644
> > > > --- a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> > > > +++ b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> > > > @@ -51,14 +51,11 @@
> > > > #define VHUB_CTRL_UPSTREAM_CONNECT (1 << 0)
> > > >
> > > > /* IER & ISR */
> > > > +#define VHUB_IRQ_DEV1_BIT 9
> > > > #define VHUB_IRQ_USB_CMD_DEADLOCK (1 << 18)
> > > > #define VHUB_IRQ_EP_POOL_NAK (1 << 17)
> > > > #define VHUB_IRQ_EP_POOL_ACK_STALL (1 << 16)
> > > > -#define VHUB_IRQ_DEVICE5 (1 << 13)
> > > > -#define VHUB_IRQ_DEVICE4 (1 << 12)
> > > > -#define VHUB_IRQ_DEVICE3 (1 << 11)
> > > > -#define VHUB_IRQ_DEVICE2 (1 << 10)
> > > > -#define VHUB_IRQ_DEVICE1 (1 << 9)
> > > > +#define VHUB_IRQ_DEVICE1 (1 <<
> > > > (VHUB_IRQ_DEV1_BIT))
> > > > #define VHUB_IRQ_BUS_RESUME (1 << 8)
> > > > #define VHUB_IRQ_BUS_SUSPEND (1 << 7)
> > > > #define VHUB_IRQ_BUS_RESET (1 << 6)
> > > > @@ -402,6 +399,7 @@ struct ast_vhub {
> > > > /* Per-port info */
> > > > struct ast_vhub_port *ports;
> > > > u32 max_ports;
> > > > + u32 port_irq_mask;
> > > >
> > > > /* Generic EP data structures */
> > > > struct ast_vhub_ep *epns;
> > > > --
> > > > 2.17.1
> > > >
> >
On Mon, 2020-04-06 at 23:02 -0700, Tao Ren wrote:
> I ran some testing on my ast2400 and ast2500 BMC and looks like the
> for() loop runs faster than for_each_set_bit_from() loop in my
> environment. I'm not sure if something needs to be revised in my test
> code, but please kindly share your suggestions:
>
> I use get_cycles() to calculate execution time of 2 different loops, and
> ast_vhub_dev_irq() is replaced with barrier() to avoid "noise"; below
> are the results:
>
> - when downstream port number is 5 and only 1 irq bit is set, it takes
> ~30 cycles to finish for_each_set_bit() loop, and 20-25 cycles to
> finish the for() loop.
>
> - if downstream port number is 5 and all 5 bits are set, then
> for_each_set_bit() loop takes ~50 cycles and for() loop takes ~25
> cycles.
>
> - when I increase downsteam port number to 16 and set 1 irq bit, the
> for_each_set_bit() loop takes ~30 cycles and for() loop takes 25
> cycles. It's a little surprise to me because I thought for() loop
> would cost 60+ cycles (3 times of the value when port number is 5).
>
> - if downstream port number is 16 and all irq status bits are set,
> then for_each_set_bit() loop takes 60-70 cycles and for() loop takes
> 30+ cycles.
I suspect the CPU doesn't have an efficient find-zero-bit primitive,
check the generated asm. In that case I would go back to the simple for
loop.
Cheers,
Ben.
On Wed, Apr 08, 2020 at 09:36:16AM +1000, Benjamin Herrenschmidt wrote:
> On Mon, 2020-04-06 at 23:02 -0700, Tao Ren wrote:
> > I ran some testing on my ast2400 and ast2500 BMC and looks like the
> > for() loop runs faster than for_each_set_bit_from() loop in my
> > environment. I'm not sure if something needs to be revised in my test
> > code, but please kindly share your suggestions:
> >
> > I use get_cycles() to calculate execution time of 2 different loops, and
> > ast_vhub_dev_irq() is replaced with barrier() to avoid "noise"; below
> > are the results:
> >
> > - when downstream port number is 5 and only 1 irq bit is set, it takes
> > ~30 cycles to finish for_each_set_bit() loop, and 20-25 cycles to
> > finish the for() loop.
> >
> > - if downstream port number is 5 and all 5 bits are set, then
> > for_each_set_bit() loop takes ~50 cycles and for() loop takes ~25
> > cycles.
> >
> > - when I increase downsteam port number to 16 and set 1 irq bit, the
> > for_each_set_bit() loop takes ~30 cycles and for() loop takes 25
> > cycles. It's a little surprise to me because I thought for() loop
> > would cost 60+ cycles (3 times of the value when port number is 5).
> >
> > - if downstream port number is 16 and all irq status bits are set,
> > then for_each_set_bit() loop takes 60-70 cycles and for() loop takes
> > 30+ cycles.
>
> I suspect the CPU doesn't have an efficient find-zero-bit primitive,
> check the generated asm. In that case I would go back to the simple for
> loop.
>
> Cheers,
> Ben.
_find_next_bit_le() function is defined in arch/arm/lib/findbit.S. I'm
looking at the code: will run more tests and send out patch v4 with
simple for loop later.
Cheers,
Tao