* [PATCH] softirq: Reserve a bit in tasklet.state for the user
@ 2017-01-23 15:33 Chris Wilson
2017-01-23 15:44 ` Jens Axboe
0 siblings, 1 reply; 5+ messages in thread
From: Chris Wilson @ 2017-01-23 15:33 UTC (permalink / raw)
To: linux-kernel
Cc: Chris Wilson, Thomas Gleixner, Jens Axboe, Hannes Reinecke,
Bjorn Helgaas, Chen Fan, Alexander Potapenko
Allow the user to communicate with the tasklet through the atomic state
field by assigning a bit for their use. This can be used, for example,
to differentiate between a tasklet called following an irq or from
process context, where some hardware state may only be valid after the
irq.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
Cc: Alexander Potapenko <glider@google.com>
---
include/linux/interrupt.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 53144e78a369..ab321552089b 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -542,7 +542,8 @@ struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(1), func, data }
enum
{
TASKLET_STATE_SCHED, /* Tasklet is scheduled for execution */
- TASKLET_STATE_RUN /* Tasklet is running (SMP only) */
+ TASKLET_STATE_RUN, /* Tasklet is running (SMP only) */
+ TASKLET_STATE_USER /* Reserved for use by the owner */
};
#ifdef CONFIG_SMP
--
2.11.0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] softirq: Reserve a bit in tasklet.state for the user
2017-01-23 15:33 [PATCH] softirq: Reserve a bit in tasklet.state for the user Chris Wilson
@ 2017-01-23 15:44 ` Jens Axboe
2017-01-23 15:57 ` [PATCH] drm/i915: Only run execlist context-switch handler after an interrupt Chris Wilson
2017-01-23 15:59 ` [PATCH] softirq: Reserve a bit in tasklet.state for the user Thomas Gleixner
0 siblings, 2 replies; 5+ messages in thread
From: Jens Axboe @ 2017-01-23 15:44 UTC (permalink / raw)
To: Chris Wilson, linux-kernel
Cc: Thomas Gleixner, Hannes Reinecke, Bjorn Helgaas, Chen Fan,
Alexander Potapenko
On 01/23/2017 08:33 AM, Chris Wilson wrote:
> Allow the user to communicate with the tasklet through the atomic state
> field by assigning a bit for their use. This can be used, for example,
> to differentiate between a tasklet called following an irq or from
> process context, where some hardware state may only be valid after the
> irq.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Jens Axboe <axboe@kernel.dk>
> Cc: Hannes Reinecke <hare@suse.com>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> Cc: Alexander Potapenko <glider@google.com>
> ---
> include/linux/interrupt.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
> index 53144e78a369..ab321552089b 100644
> --- a/include/linux/interrupt.h
> +++ b/include/linux/interrupt.h
> @@ -542,7 +542,8 @@ struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(1), func, data }
> enum
> {
> TASKLET_STATE_SCHED, /* Tasklet is scheduled for execution */
> - TASKLET_STATE_RUN /* Tasklet is running (SMP only) */
> + TASKLET_STATE_RUN, /* Tasklet is running (SMP only) */
> + TASKLET_STATE_USER /* Reserved for use by the owner */
> };
I have no problem making that distinction, but it's impossible to ack
this patch without having seen how you plan to utilize it, as the patch
is meaningless on its own.
--
Jens Axboe
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] drm/i915: Only run execlist context-switch handler after an interrupt
2017-01-23 15:44 ` Jens Axboe
@ 2017-01-23 15:57 ` Chris Wilson
2017-01-23 15:59 ` [PATCH] softirq: Reserve a bit in tasklet.state for the user Thomas Gleixner
1 sibling, 0 replies; 5+ messages in thread
From: Chris Wilson @ 2017-01-23 15:57 UTC (permalink / raw)
To: linux-kernel, axboe; +Cc: tglx, hare, bhelgaas, glider, Chris Wilson
Mark when we run the execlist tasklet following the interrupt, so we
don't probe a potentially uninitialised register when submitting the
contexts multiple times before the hardware responds.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/i915_irq.c | 7 +++++--
drivers/gpu/drm/i915/intel_lrc.c | 3 ++-
drivers/gpu/drm/i915/intel_ringbuffer.h | 1 +
3 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 6fefc34ef602..42be116dd33d 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1349,8 +1349,11 @@ gen8_cs_irq_handler(struct intel_engine_cs *engine, u32 iir, int test_shift)
{
if (iir & (GT_RENDER_USER_INTERRUPT << test_shift))
notify_ring(engine);
- if (iir & (GT_CONTEXT_SWITCH_INTERRUPT << test_shift))
- tasklet_schedule(&engine->irq_tasklet);
+
+ if (iir & (GT_CONTEXT_SWITCH_INTERRUPT << test_shift)) {
+ set_bit(IRQ_CTX_SWITCH, &engine->irq_tasklet.state);
+ tasklet_hi_schedule(&engine->irq_tasklet);
+ }
}
static irqreturn_t gen8_gt_irq_ack(struct drm_i915_private *dev_priv,
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 65bb877a726d..b55e38a590c1 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -578,7 +578,7 @@ static void intel_lrc_irq_handler(unsigned long data)
intel_uncore_forcewake_get(dev_priv, engine->fw_domains);
- if (!execlists_elsp_idle(engine)) {
+ while (test_and_clear_bit(IRQ_CTX_SWITCH, &engine->irq_tasklet.state)) {
u32 __iomem *csb_mmio =
dev_priv->regs + i915_mmio_reg_offset(RING_CONTEXT_STATUS_PTR(engine));
u32 __iomem *buf =
@@ -1347,6 +1347,7 @@ static int gen8_init_common_ring(struct intel_engine_cs *engine)
DRM_DEBUG_DRIVER("Execlists enabled for %s\n", engine->name);
/* After a GPU reset, we may have requests to replay */
+ clear_bit(IRQ_CTX_SWITCH, &engine->irq_tasklet.state);
if (!execlists_elsp_idle(engine)) {
engine->execlist_port[0].count = 0;
engine->execlist_port[1].count = 0;
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 34cdbb6350a8..c63f39d47fdd 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -373,6 +373,7 @@ struct intel_engine_cs {
/* Execlists */
struct tasklet_struct irq_tasklet;
+#define IRQ_CTX_SWITCH (BITS_PER_LONG - 1) /* TASKLET_STATE_USER */
struct execlist_port {
struct drm_i915_gem_request *request;
unsigned int count;
--
2.11.0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] softirq: Reserve a bit in tasklet.state for the user
2017-01-23 15:44 ` Jens Axboe
2017-01-23 15:57 ` [PATCH] drm/i915: Only run execlist context-switch handler after an interrupt Chris Wilson
@ 2017-01-23 15:59 ` Thomas Gleixner
2017-01-23 16:10 ` Peter Zijlstra
1 sibling, 1 reply; 5+ messages in thread
From: Thomas Gleixner @ 2017-01-23 15:59 UTC (permalink / raw)
To: Jens Axboe
Cc: Chris Wilson, LKML, Hannes Reinecke, Bjorn Helgaas, Chen Fan,
Alexander Potapenko, Ingo Molnar, Peter Zijlstra
On Mon, 23 Jan 2017, Jens Axboe wrote:
> On 01/23/2017 08:33 AM, Chris Wilson wrote:
> > Allow the user to communicate with the tasklet through the atomic state
> > field by assigning a bit for their use. This can be used, for example,
> > to differentiate between a tasklet called following an irq or from
> > process context, where some hardware state may only be valid after the
> > irq.
> >
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Thomas Gleixner <tglx@linutronix.de>
> > Cc: Jens Axboe <axboe@kernel.dk>
> > Cc: Hannes Reinecke <hare@suse.com>
> > Cc: Bjorn Helgaas <bhelgaas@google.com>
> > Cc: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> > Cc: Alexander Potapenko <glider@google.com>
> > ---
> > include/linux/interrupt.h | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
> > index 53144e78a369..ab321552089b 100644
> > --- a/include/linux/interrupt.h
> > +++ b/include/linux/interrupt.h
> > @@ -542,7 +542,8 @@ struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(1), func, data }
> > enum
> > {
> > TASKLET_STATE_SCHED, /* Tasklet is scheduled for execution */
> > - TASKLET_STATE_RUN /* Tasklet is running (SMP only) */
> > + TASKLET_STATE_RUN, /* Tasklet is running (SMP only) */
> > + TASKLET_STATE_USER /* Reserved for use by the owner */
> > };
>
> I have no problem making that distinction, but it's impossible to ack
> this patch without having seen how you plan to utilize it, as the patch
> is meaningless on its own.
Right and w/o well defined semantics of this bit it's not at all
acceptable. tasklets have vagely semantics already, we really don't need to
increase that horror.
Thanks,
tglx
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] softirq: Reserve a bit in tasklet.state for the user
2017-01-23 15:59 ` [PATCH] softirq: Reserve a bit in tasklet.state for the user Thomas Gleixner
@ 2017-01-23 16:10 ` Peter Zijlstra
0 siblings, 0 replies; 5+ messages in thread
From: Peter Zijlstra @ 2017-01-23 16:10 UTC (permalink / raw)
To: Thomas Gleixner
Cc: Jens Axboe, Chris Wilson, LKML, Hannes Reinecke, Bjorn Helgaas,
Chen Fan, Alexander Potapenko, Ingo Molnar
On Mon, Jan 23, 2017 at 04:59:32PM +0100, Thomas Gleixner wrote:
> On Mon, 23 Jan 2017, Jens Axboe wrote:
>
> > On 01/23/2017 08:33 AM, Chris Wilson wrote:
> > > Allow the user to communicate with the tasklet through the atomic state
> > > field by assigning a bit for their use. This can be used, for example,
> > > to differentiate between a tasklet called following an irq or from
> > > process context, where some hardware state may only be valid after the
> > > irq.
Egads, this sounds like a horrible hack. What does 'after and irq' even
mean?
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2017-01-23 16:11 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2017-01-23 15:33 [PATCH] softirq: Reserve a bit in tasklet.state for the user Chris Wilson
2017-01-23 15:44 ` Jens Axboe
2017-01-23 15:57 ` [PATCH] drm/i915: Only run execlist context-switch handler after an interrupt Chris Wilson
2017-01-23 15:59 ` [PATCH] softirq: Reserve a bit in tasklet.state for the user Thomas Gleixner
2017-01-23 16:10 ` Peter Zijlstra
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