[PATCH] drm/amdgpu: defer test IBs on the rings at boot
S, Shirish
sshankar at amd.com
Fri Apr 13 08:38:55 UTC 2018
On 4/13/2018 12:38 PM, Christian König wrote:
> Am 13.04.2018 um 09:01 schrieb S, Shirish:
>>
>>
>> On 4/13/2018 11:53 AM, Christian König wrote:
>>> Am 13.04.2018 um 06:07 schrieb Shirish S:
>>>> amdgpu_ib_ring_tests() runs test IB's on rings at boot
>>>> contributes to ~500 ms of amdgpu driver's boot time.
>>>>
>>>> This patch defers it and adds a check to report
>>>> in amdgpu_info_ioctl() if it was scheduled or not.
>>>
>>> That is rather suboptimal, but see below.
>>>
>> Which part is sub-optimal, deferring or checking if the work is
>> scheduled?
>
> That was about the check. We should wait for the test to finish
> instead of printing an error and continuing.
>
Done. Have made this change in V2.
>>>>
>>>> Signed-off-by: Shirish S <shirish.s at amd.com>
>>>> ---
>>>> drivers/gpu/drm/amd/amdgpu/amdgpu.h | 2 ++
>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 20 +++++++++++++++++---
>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c | 3 +++
>>>> 3 files changed, 22 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>>> index 5734871..ae8f722 100644
>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>>> @@ -1611,6 +1611,8 @@ struct amdgpu_device {
>>>> /* delayed work_func for deferring clockgating during
>>>> resume */
>>>> struct delayed_work late_init_work;
>>>> + /* delayed work_func to defer testing IB's on rings during
>>>> boot */
>>>> + struct delayed_work late_init_test_ib_work;
>>>
>>> You must put the IB test into the late_init_work as well, otherwise
>>> the two delayed workers can race with each other.
>>>
>> I thought from the comment above the declaration, its clear why i am
>> creating 2 work structures.
>> late_init_work is to optimize resume time and late_init_test_ib_work
>> is to optimize the boot time.
>> There cant be race as the context in which they are called are
>> totally different.
>
> Late init enables power and clock gating. If I'm not completely
> mistaken we don't do the power/clock gating earlier because we had to
> wait for the IB test to finish.
>
> Could be that modern ASICs have additional logic to prevent that, but
> the last time I worked on this power gating a block while you run
> something on it could even crash the whole system.
>
>>>> struct amdgpu_virt virt;
>>>> /* firmware VRAM reservation */
>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>> index 1762eb4..e65a5e6 100644
>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>> @@ -63,6 +63,7 @@ MODULE_FIRMWARE("amdgpu/vega12_gpu_info.bin");
>>>> MODULE_FIRMWARE("amdgpu/raven_gpu_info.bin");
>>>> #define AMDGPU_RESUME_MS 2000
>>>> +#define AMDGPU_IB_TEST_SCHED_MS 2000
>>>> static const char *amdgpu_asic_name[] = {
>>>> "TAHITI",
>>>> @@ -2105,6 +2106,16 @@ bool amdgpu_device_asic_has_dc_support(enum
>>>> amd_asic_type asic_type)
>>>> }
>>>> }
>>>> +static void amdgpu_device_late_init_test_ib_func_handler(struct
>>>> work_struct *work)
>>>> +{
>>>> + struct amdgpu_device *adev =
>>>> + container_of(work, struct amdgpu_device,
>>>> late_init_test_ib_work.work);
>>>> + int r = amdgpu_ib_ring_tests(adev);
>>>> +
>>>> + if (r)
>>>> + DRM_ERROR("ib ring test failed (%d).\n", r);
>>>> +}
>>>> +
>>>> /**
>>>> * amdgpu_device_has_dc_support - check if dc is supported
>>>> *
>>>> @@ -2212,6 +2223,8 @@ int amdgpu_device_init(struct amdgpu_device
>>>> *adev,
>>>> INIT_LIST_HEAD(&adev->ring_lru_list);
>>>> spin_lock_init(&adev->ring_lru_list_lock);
>>>> + INIT_DELAYED_WORK(&adev->late_init_test_ib_work,
>>>> + amdgpu_device_late_init_test_ib_func_handler);
>>>> INIT_DELAYED_WORK(&adev->late_init_work,
>>>> amdgpu_device_ip_late_init_func_handler);
>>>> @@ -2374,9 +2387,9 @@ int amdgpu_device_init(struct amdgpu_device
>>>> *adev,
>>>> goto failed;
>>>> }
>>>> - r = amdgpu_ib_ring_tests(adev);
>>>> - if (r)
>>>> - DRM_ERROR("ib ring test failed (%d).\n", r);
>>>> + /* Schedule amdgpu_ib_ring_tests() */
>>>> + mod_delayed_work(system_wq, &adev->late_init_test_ib_work,
>>>> + msecs_to_jiffies(AMDGPU_IB_TEST_SCHED_MS));
>>>
>>> That doesn't work like you intended. mod_delayed_work() overrides
>>> the existing handler.
>>>
>>> What you wanted to use is queue_delayed_work(), but as I said we
>>> should only have one delayed worker.
>> mod_delayed_work() is safer and optimal method that replaces
>> cancel_delayed_work() followed by queue_delayed_work().
>> (https://lkml.org/lkml/2011/2/3/175)
>> But if you strongly insist i don't mind changing it.
>
> Well, mod_delayed_work() does NOT replace queue_delayed_work(). Those
> two functions are for different use cases.
>
> The link you posted actually explains it quite well:
>> So, cancel_delayed_work() followed by queue_delayed_work() schedules
>> the work to be executed at the specified time regardless of the
>> current pending state while queue_delayed_work() takes effect iff
>> currently the work item is not pending.
>
> queue_delayed_work() takes only effect if the work item is not already
> pending/executing.
>
> In other words with queue_delayed_work() you don't risk executing
> things twice when the work is already executing.
>
> While with mod_delayed_work() you absolutely make sure to execute
> things twice when it is already running.
>
> If I'm not completely mistaken it should not matter in this case, but
> queue_delayed_work() is used more commonly I think.
>
Since this work is run only once that too at the boot, we wont have a
case where in it will be required to
check if its pending or not.
Anyway, i have changed mod_delayed_work() to queue_delayed_work() and
added flush_delayed_work() in amdgpu_info_ioctl() in V2.
Thanks.
Regards,
Shirish S
>>>
>>>> if (amdgpu_sriov_vf(adev))
>>>> amdgpu_virt_init_data_exchange(adev);
>>>> @@ -2469,6 +2482,7 @@ void amdgpu_device_fini(struct amdgpu_device
>>>> *adev)
>>>> }
>>>> adev->accel_working = false;
>>>> cancel_delayed_work_sync(&adev->late_init_work);
>>>> + cancel_delayed_work_sync(&adev->late_init_test_ib_work);
>>>> /* free i2c buses */
>>>> if (!amdgpu_device_has_dc_support(adev))
>>>> amdgpu_i2c_fini(adev);
>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
>>>> index 487d39e..057bd9a 100644
>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
>>>> @@ -279,6 +279,9 @@ static int amdgpu_info_ioctl(struct drm_device
>>>> *dev, void *data, struct drm_file
>>>> if (!info->return_size || !info->return_pointer)
>>>> return -EINVAL;
>>>> + if (delayed_work_pending(&adev->late_init_test_ib_work))
>>>> + DRM_ERROR("IB test on ring not executed\n");
>>>> +
>>>
>>> Please use flush_delayed_work() instead of issuing and error here.
>>>
>> Agree, wasn't sure of what to do here :).
>> So i will re-spin with the flush part added. Hope this reply
>> clarifies your comments.
>> Thanks.
>> Regards,
>> Shirish S
>>> Regards,
>>> Christian.
>>>
>>>> switch (info->query) {
>>>> case AMDGPU_INFO_ACCEL_WORKING:
>>>> ui32 = adev->accel_working;
>>>
>>
>
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