[PATCH i-g-t 1/2] lib/xe_eudebug: Introduce preempt_timeout helpers

[Manszewski, Christoph]

Hi Zbigniew,

On 27.09.2024 07:18, Zbigniew Kempczyński wrote:
> On Thu, Sep 26, 2024 at 04:54:53PM +0200, Grzegorzek, Dominik wrote:
>> On Thu, 2024-09-26 at 14:18 +0200, Dominik Karol Piątkowski wrote:
>>> This patch introduces preempt_timeout helpers:
>>>   - xe_eudebug_set_preempt_timeout_to_max
>>>     Sets preempt_timeout_us for given engine_class to maximum.
>>>   - xe_eudebug_restore_preempt_timeout
>>>     Sets preempt_timeout_us for given engine_class to previous value.
>>>
>>
>> I think this should really go to igt_sysfs.c. And in sligtly different form:
>> How about sth like:
> 
> We're compiling lib/xe_eudebug.c conditionally so I wouldn't pollute igt_sysfs.c
> with eudebug code (at least yet).

I am a little bit confused by this comment as this is not eudebug 
specific code. The eudebug series did introduce some code to common/core 
igt library parts (like gpgpu_shader or intel_bachbuffer) which seemed 
to be fine (and rightly so IMO). I am not sure why this case is any 
different.

The only reason I could think of was that igt_sysfs.c might be for 
generic and not i915/Xe specific functions but from what I see, there is 
plenty i915/Xe specific stuff in there.

Thanks,
Christoph

> 
> --
> Zbigniew
> 
>>
>> igt_sysfs_engine_set_property(engines_fd, "preempt_timeout_us", value);
>> igt_sysfs_engine_set_property_bound(engines_fd, "preempt_timeout_us", max);
>>
>> ,where max is a bool variable which tells whether it should be min or max.
>>
>> To find engines_fd xe_sysfs_engine_open could be used.
>>
>> Regards,
>> Dominik
>>
>>> Signed-off-by: Dominik Karol Piątkowski <dominik.karol.piatkowski at intel.com>
>>> ---
>>>   lib/xe/xe_eudebug.c | 120 ++++++++++++++++++++++++++++++++++++++++++++
>>>   lib/xe/xe_eudebug.h |   3 ++
>>>   2 files changed, 123 insertions(+)
>>>
>>> diff --git a/lib/xe/xe_eudebug.c b/lib/xe/xe_eudebug.c
>>> index 2c7cd2ae1..229f9e6a1 100644
>>> --- a/lib/xe/xe_eudebug.c
>>> +++ b/lib/xe/xe_eudebug.c
>>> @@ -16,6 +16,7 @@
>>>   #include "intel_pat.h"
>>>   #include "xe_eudebug.h"
>>>   #include "xe_ioctl.h"
>>> +#include "xe_drm.h"
>>>   
>>>   struct event_trigger {
>>>   	xe_eudebug_trigger_fn fn;
>>> @@ -1717,6 +1718,125 @@ bool xe_eudebug_enable(int fd, bool enable)
>>>   	return old;
>>>   }
>>>   
>>> +/**
>>> + * xe_eudebug_set_preempt_timeout_to_max
>>> + * @fd: xe client
>>> + * @engine_class: engine class to modify (drm_xe_engine_class_instance->engine_class)
>>> + * @value: pointer to variable to store previous preempt_timeout value in, needed for restore
>>> + *
>>> + * Sets preempt_timeout_us for given engine_class to maximum.
>>> + *
>>> + * Returns: true on success, false on failure.
>>> + */
>>> +bool xe_eudebug_set_preempt_timeout_to_max(int fd, uint16_t engine_class, uint32_t *value)
>>> +{
>>> +	int engines_fd;
>>> +	int gt_fd;
>>> +	uint32_t max_value;
>>> +
>>> +	igt_assert(engine_class == DRM_XE_ENGINE_CLASS_RENDER ||
>>> +		   engine_class == DRM_XE_ENGINE_CLASS_COMPUTE);
>>> +
>>> +	gt_fd = xe_sysfs_gt_open(fd, 0);
>>> +	if (gt_fd == -1) {
>>> +		igt_debug("Failed to open gt.\n");
>>> +
>>> +		return false;
>>> +	}
>>> +
>>> +	if (engine_class == DRM_XE_ENGINE_CLASS_RENDER)
>>> +		engines_fd = openat(gt_fd, "engines/rcs", O_RDONLY);
>>> +	else
>>> +		engines_fd = openat(gt_fd, "engines/ccs", O_RDONLY);
>>> +
>>> +	if (engines_fd == -1) {
>>> +		igt_debug("Failed to open engine class.\n");
>>> +		close(gt_fd);
>>> +
>>> +		return false;
>>> +	}
>>> +
>>> +	if (!__igt_sysfs_get_u32(engines_fd, "preempt_timeout_us", value)) {
>>> +		igt_debug("Failed to read preempt_timeout_us.\n");
>>> +		close(engines_fd);
>>> +		close(gt_fd);
>>> +
>>> +		return false;
>>> +	}
>>> +
>>> +	if (!__igt_sysfs_get_u32(engines_fd, "preempt_timeout_max", &max_value)) {
>>> +		igt_debug("Failed to read preempt_timeout_max.\n");
>>> +		close(engines_fd);
>>> +		close(gt_fd);
>>> +
>>> +		return false;
>>> +	}
>>> +
>>> +	if (!__igt_sysfs_set_u32(engines_fd, "preempt_timeout_us", max_value)) {
>>> +		igt_debug("Failed to write preempt_timeout_us.\n");
>>> +		close(engines_fd);
>>> +		close(gt_fd);
>>> +
>>> +		return false;
>>> +	}
>>> +
>>> +	close(engines_fd);
>>> +	close(gt_fd);
>>> +
>>> +	return true;
>>> +}
>>> +
>>> +/**
>>> + * xe_eudebug_restore_preempt_timeout
>>> + * @fd: xe client
>>> + * @engine_class: engine class to modify (drm_xe_engine_class_instance->engine_class)
>>> + * @value: previous preempt_timeout value
>>> + *
>>> + * Sets preempt_timeout_us for given engine_class to previous value.
>>> + *
>>> + * Returns: true on success, false on failure.
>>> + */
>>> +bool xe_eudebug_restore_preempt_timeout(int fd, uint16_t engine_class, uint32_t value)
>>> +{
>>> +	int engines_fd;
>>> +	int gt_fd;
>>> +
>>> +	igt_assert(engine_class == DRM_XE_ENGINE_CLASS_RENDER ||
>>> +		   engine_class == DRM_XE_ENGINE_CLASS_COMPUTE);
>>> +
>>> +	gt_fd = xe_sysfs_gt_open(fd, 0);
>>> +	if (gt_fd == -1) {
>>> +		igt_debug("Failed to open gt.\n");
>>> +
>>> +		return false;
>>> +	}
>>> +
>>> +	if (engine_class == DRM_XE_ENGINE_CLASS_RENDER)
>>> +		engines_fd = openat(gt_fd, "engines/rcs", O_RDONLY);
>>> +	else
>>> +		engines_fd = openat(gt_fd, "engines/ccs", O_RDONLY);
>>> +
>>> +	if (engines_fd == -1) {
>>> +		igt_debug("Failed to open engine class.\n");
>>> +		close(gt_fd);
>>> +
>>> +		return false;
>>> +	}
>>> +
>>> +	if (!__igt_sysfs_set_u32(engines_fd, "preempt_timeout_us", value)) {
>>> +		igt_debug("Failed to write preempt_timeout_us.\n");
>>> +		close(engines_fd);
>>> +		close(gt_fd);
>>> +
>>> +		return false;
>>> +	}
>>> +
>>> +	close(engines_fd);
>>> +	close(gt_fd);
>>> +
>>> +	return true;
>>> +}
>>> +
>>>   /* Eu debugger wrappers around resource creating xe ioctls. */
>>>   
>>>   /**
>>> diff --git a/lib/xe/xe_eudebug.h b/lib/xe/xe_eudebug.h
>>> index 29ab68fee..144035862 100644
>>> --- a/lib/xe/xe_eudebug.h
>>> +++ b/lib/xe/xe_eudebug.h
>>> @@ -167,6 +167,9 @@ void xe_eudebug_client_set_data(struct xe_eudebug_client *c, void *ptr);
>>>   
>>>   bool xe_eudebug_enable(int fd, bool enable);
>>>   
>>> +bool xe_eudebug_set_preempt_timeout_to_max(int fd, uint16_t engine_class, uint32_t *value);
>>> +bool xe_eudebug_restore_preempt_timeout(int fd, uint16_t engine_class, uint32_t value);
>>> +
>>>   int xe_eudebug_client_open_driver(struct xe_eudebug_client *c);
>>>   void xe_eudebug_client_close_driver(struct xe_eudebug_client *c, int fd);
>>>   uint32_t xe_eudebug_client_vm_create(struct xe_eudebug_client *c, int fd,
>>