[Intel-xe] [PATCH v5 3/3] drm/xe/pmu: Enable PMU interface
Aravind Iddamsetty
aravind.iddamsetty at linux.intel.com
Thu Aug 31 22:11:09 UTC 2023
On 31/08/23 22:28, Dixit, Ashutosh wrote:
HI Ashutosh,
> On Thu, 31 Aug 2023 03:29:11 -0700, Aravind Iddamsetty wrote:
> Hi Aravind,
>
> Hmm, what happened to the email formatting here?
not sure, some how my email client is showing proper or I messed up.
>
>> On Tue, 29 Aug 2023 22:15:44 -0700, Aravind Iddamsetty wrote:
>>
>> diff --git a/drivers/gpu/drm/xe/xe_pmu.c b/drivers/gpu/drm/xe/xe_pmu.c
>> new file mode 100644
>> index 000000000000..41dd422812ff
>> --- /dev/null
>> +++ b/drivers/gpu/drm/xe/xe_pmu.c
>> @@ -0,0 +1,679 @@
>> +// SPDX-License-Identifier: MIT
>> +/*
>> + * Copyright © 2023 Intel Corporation
>> + */
>> +
>> +#include <drm/drm_drv.h>
>> +#include <drm/drm_managed.h>
>> +#include <drm/xe_drm.h>
>> +
>> +#include "regs/xe_gt_regs.h"
>> +#include "xe_device.h"
>> +#include "xe_gt_clock.h"
>> +#include "xe_mmio.h"
>> +
>> +static cpumask_t xe_pmu_cpumask;
>> +static unsigned int xe_pmu_target_cpu = -1;
>> +
>> +static unsigned int config_gt_id(const u64 config)
>> +{
>> + return config >> __XE_PMU_GT_SHIFT;
>> +}
>> +
>> +static u64 config_counter(const u64 config)
>> +{
>> + return config & ~(~0ULL << __XE_PMU_GT_SHIFT);
>> +}
>> +
>> +static int engine_busyness_sample_type(u64 config)
>> +{
>> + int type = 0;
>>
>>
>> Why initialize? The switch statement should have a default with a BUG/WARN_ON
>> below? Also see the comment below.
>>
>> +
>> + switch (config) {
>> + case XE_PMU_RENDER_GROUP_BUSY(0):
>> + type = __XE_SAMPLE_RENDER_GROUP_BUSY;
>> + break;
>> + case XE_PMU_COPY_GROUP_BUSY(0):
>> + type = __XE_SAMPLE_COPY_GROUP_BUSY;
>> + break;
>> + case XE_PMU_MEDIA_GROUP_BUSY(0):
>> + type = __XE_SAMPLE_MEDIA_GROUP_BUSY;
>> + break;
>> + case XE_PMU_ANY_ENGINE_GROUP_BUSY(0):
>> + type = __XE_SAMPLE_ANY_ENGINE_GROUP_BUSY;
>> + break;
>> + }
>> +
>> + return type;
>> +}
>>
>>
>> I am thinking this function is not really needed. We can just do:
>>
>> int sample_type = config - 1;
>>
>> or
>>
>> int sample_type = config_counter(config) - 1;
>>
>> It might not always be true in future, the configs can start from any range.
> Disagree. This is uapi. Once it is exposed it cannot change. I am talking
> about this:
>
> +#define XE_PMU_INTERRUPTS(gt) ___XE_PMU_OTHER(gt, 0)
> +#define XE_PMU_RENDER_GROUP_BUSY(gt) ___XE_PMU_OTHER(gt, 1)
> +#define XE_PMU_COPY_GROUP_BUSY(gt) ___XE_PMU_OTHER(gt, 2)
> +#define XE_PMU_MEDIA_GROUP_BUSY(gt) ___XE_PMU_OTHER(gt, 3)
> +#define XE_PMU_ANY_ENGINE_GROUP_BUSY(gt) ___XE_PMU_OTHER(gt, 4)
>
> How can this "start from any range"? We can only add new counters after
> these, not before these, correct?
I didn't mean to say that these particular one's would change but any
future new events that might fall into these categories might start
from a different range. sorry for the confusion.
Your suggestion makes it looks simple but somehow i wanted to tie this to
the enums we defined in sample array, so ya will check one more time if
it doesn't really makes any sense will clean it up.
>
>> in engine_group_busyness_read? See comment at __xe_pmu_event_read below.
>>
>> +
>> +static void xe_pmu_event_destroy(struct perf_event *event)
>> +{
>> + struct xe_device *xe =
>> + container_of(event->pmu, typeof(*xe), pmu.base);
>> +
>> + drm_WARN_ON(&xe->drm, event->parent);
>> +
>> + drm_dev_put(&xe->drm);
>> +}
>> +
>> +static u64 __engine_group_busyness_read(struct xe_gt *gt, int sample_type)
>> +{
>> + u64 val = 0;
> No need to initialize here I think. We are not really expecting to drop
> into the default case, which should be caught much before we enter this
> function.
>
>> +
>> + switch (sample_type) {
>> + case __XE_SAMPLE_RENDER_GROUP_BUSY:
>> + val = xe_mmio_read32(gt, XE_OAG_RENDER_BUSY_FREE);
>> + break;
>> + case __XE_SAMPLE_COPY_GROUP_BUSY:
>> + val = xe_mmio_read32(gt, XE_OAG_BLT_BUSY_FREE);
>> + break;
>> + case __XE_SAMPLE_MEDIA_GROUP_BUSY:
>> + val = xe_mmio_read32(gt, XE_OAG_ANY_MEDIA_FF_BUSY_FREE);
>> + break;
>> + case __XE_SAMPLE_ANY_ENGINE_GROUP_BUSY:
>> + val = xe_mmio_read32(gt, XE_OAG_RC0_ANY_ENGINE_BUSY_FREE);
>> + break;
>> + default:
>> + drm_warn(>->tile->xe->drm, "unknown pmu event\n");
>> + }
>> +
>> + return xe_gt_clock_cycles_to_ns(gt, val * 16);
>> +}
>> +
>> +static u64 engine_group_busyness_read(struct xe_gt *gt, u64 config)
>> +{
>> + int sample_type = engine_busyness_sample_type(config);
>>
>>
>> If config is event->attr.config, this can just be 'config_counter(config) - 1'.
>> See comment at __xe_pmu_event_read below.
>>
>> + const unsigned int gt_id = gt->info.id;
>> + struct xe_device *xe = gt->tile->xe;
>> + struct xe_pmu *pmu = &xe->pmu;
>> + unsigned long flags;
>> + bool device_awake;
>> + u64 val;
>> +
>> + device_awake = xe_device_mem_access_get_if_ongoing(xe);
>> + if (device_awake) {
>> + XE_WARN_ON(xe_force_wake_get(gt_to_fw(gt), XE_FW_GT));
>> + val = __engine_group_busyness_read(gt, sample_type);
>> + XE_WARN_ON(xe_force_wake_put(gt_to_fw(gt), XE_FW_GT));
>> + xe_device_mem_access_put(xe);
>> + }
>> +
>> + spin_lock_irqsave(&pmu->lock, flags);
>> +
>> + if (device_awake)
>> + pmu->sample[gt_id][sample_type] = val;
>> + else
>> + val = pmu->sample[gt_id][sample_type];
>> +
>> + spin_unlock_irqrestore(&pmu->lock, flags);
>> +
>> + return val;
>> +}
>> +
>> +static void engine_group_busyness_store(struct xe_gt *gt)
>> +{
>> + struct xe_pmu *pmu = >->tile->xe->pmu;
>> + unsigned int gt_id = gt->info.id;
>> + unsigned long flags;
>> + int i;
>> +
>> + spin_lock_irqsave(&pmu->lock, flags);
>> +
>> + for (i = __XE_SAMPLE_RENDER_GROUP_BUSY; i <= __XE_SAMPLE_ANY_ENGINE_GROUP_BUSY; i++) {
>> + pmu->sample[gt_id][i] = __engine_group_busyness_read(gt, i);
>>
>>
>> This is not quite right. At the minimum we need to take forcewake
>> here. Also since this is called in both suspend and runtime_suspend code
>> paths we might also need to the take the runtime_pm reference.
>>
>> The pm reference and forcewake are already taken in suspend paths hence
>> didn't add here again as this is called only from those paths.
>>
>> check xe_gt_suspend.
> Sorry, you are right, I missed it. So this is fine.
>
>
>>
>>
>> I think the simplest might be to just construct 'config'
>> (event->attr.config) here and call engine_group_busyness_read? Something
>> like:
>>
>> for (i = __XE_SAMPLE_RENDER_GROUP_BUSY; i <= __XE_SAMPLE_ANY_ENGINE_GROUP_BUSY; i++) {
>> config = ; // Construct config using gt_id and i
>> engine_group_busyness_read(gt, i);
>> }
>>
>> This will automatically save the read values in pmu->sample[][] if the
>> device is awake. Thoughts?
>>
>> I think this is best kept separate from usual read paths(which are
>> atomic) didn't want to club them. Also because forcewakes and pm
>> reference are taken separately in suspend path.
> Sure, no changes needed here. Just get rid of the braces to keep checkpatch
> happy.
>
>
>>
>>
>> + }
>> +
>> + spin_unlock_irqrestore(&pmu->lock, flags);
>> +}
>> +
>> +static int
>> +config_status(struct xe_device *xe, u64 config)
>> +{
>> + unsigned int max_gt_id = xe->info.gt_count > 1 ? 1 : 0;
>>
>>
>> What is this for? See below.
>>
>> reminiscent of my previous code, will clean it up.
>>
>>
>>
>> + unsigned int gt_id = config_gt_id(config);
>> + struct xe_gt *gt = xe_device_get_gt(xe, gt_id);
>> +
>> + if (gt_id > max_gt_id)
>>
>>
>> Maybe this can just be:
>>
>> if (gt_id >= XE_PMU_MAX_GT)
>>
>> + return -ENOENT;
>> +
>> + switch (config_counter(config)) {
>> + case XE_PMU_INTERRUPTS(0):
>> + if (gt_id)
>> + return -ENOENT;
>> + break;
>> + case XE_PMU_RENDER_GROUP_BUSY(0):
>> + case XE_PMU_COPY_GROUP_BUSY(0):
>> + case XE_PMU_ANY_ENGINE_GROUP_BUSY(0):
>> + if (gt->info.type == XE_GT_TYPE_MEDIA)
>> + return -ENOENT;
>> + break;
>> + case XE_PMU_MEDIA_GROUP_BUSY(0):
>> + if (!(gt->info.engine_mask & (BIT(XE_HW_ENGINE_VCS0) | BIT(XE_HW_ENGINE_VECS0))))
>> + return -ENOENT;
>> + break;
>> + default:
>> + return -ENOENT;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int xe_pmu_event_init(struct perf_event *event)
>> +{
>> + struct xe_device *xe =
>> + container_of(event->pmu, typeof(*xe), pmu.base);
>> + struct xe_pmu *pmu = &xe->pmu;
>> + int ret;
>> +
>> + if (pmu->closed)
>> + return -ENODEV;
>> +
>> + if (event->attr.type != event->pmu->type)
>> + return -ENOENT;
>> +
>> + /* unsupported modes and filters */
>> + if (event->attr.sample_period) /* no sampling */
>> + return -EINVAL;
>> +
>> + if (has_branch_stack(event))
>> + return -EOPNOTSUPP;
>> +
>> + if (event->cpu < 0)
>> + return -EINVAL;
>> +
>> + /* only allow running on one cpu at a time */
>> + if (!cpumask_test_cpu(event->cpu, &xe_pmu_cpumask))
>> + return -EINVAL;
>> +
>> + ret = config_status(xe, event->attr.config);
>> + if (ret)
>> + return ret;
>> +
>> + if (!event->parent) {
>> + drm_dev_get(&xe->drm);
>> + event->destroy = xe_pmu_event_destroy;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static u64 __xe_pmu_event_read(struct perf_event *event)
>> +{
>> + struct xe_device *xe =
>> + container_of(event->pmu, typeof(*xe), pmu.base);
>> + const unsigned int gt_id = config_gt_id(event->attr.config);
>> + const u64 config = config_counter(event->attr.config);
>>
>>
>> Probably nit but this config being different from event->attr.config is
>> confusing. Let's use 'event->attr.config' throughout as argument to
>> functions and use config_counter() to get rid of gt_id. So get rid of this
>> config variable.
>>
>> + struct xe_gt *gt = xe_device_get_gt(xe, gt_id);
>> + struct xe_pmu *pmu = &xe->pmu;
>> + u64 val = 0;
>> +
>> + switch (config) {
>>
>>
>> switch (config_counter(event->attr.config))
>>
>> + case XE_PMU_INTERRUPTS(0):
>> + val = READ_ONCE(pmu->irq_count);
>> + break;
>> + case XE_PMU_RENDER_GROUP_BUSY(0):
>> + case XE_PMU_COPY_GROUP_BUSY(0):
>> + case XE_PMU_ANY_ENGINE_GROUP_BUSY(0):
>> + case XE_PMU_MEDIA_GROUP_BUSY(0):
>> + val = engine_group_busyness_read(gt, config);
>>
>>
>> engine_group_busyness_read(gt, event->attr.config);
>>
>> hmmm ok.
>>
>>
>>
>> Also, need a default case.
>>
>> + }
>> +
>> + return val;
>> +}
>> +
>> +static void xe_pmu_event_read(struct perf_event *event)
>> +{
>> + struct xe_device *xe =
>> + container_of(event->pmu, typeof(*xe), pmu.base);
>> + struct hw_perf_event *hwc = &event->hw;
>> + struct xe_pmu *pmu = &xe->pmu;
>> + u64 prev, new;
>> +
>> + if (pmu->closed) {
>> + event->hw.state = PERF_HES_STOPPED;
>> + return;
>> + }
>> +again:
>> + prev = local64_read(&hwc->prev_count);
>> + new = __xe_pmu_event_read(event);
>> +
>> + if (local64_cmpxchg(&hwc->prev_count, prev, new) != prev)
>> + goto again;
>> +
>> + local64_add(new - prev, &event->count);
>> +}
>> +
>> +static void xe_pmu_enable(struct perf_event *event)
>> +{
>> + /*
>> + * Store the current counter value so we can report the correct delta
>> + * for all listeners. Even when the event was already enabled and has
>> + * an existing non-zero value.
>> + */
>> + local64_set(&event->hw.prev_count, __xe_pmu_event_read(event));
>>
>>
>> Right now nothing is being enabled here (unlike i915) so the function name
>> xe_pmu_enable looks weird. Not sure, maybe leave as is for when things get
>> added in the future?
>>
>> +static int xe_pmu_cpu_online(unsigned int cpu, struct hlist_node *node)
>> +{
>> + struct xe_pmu *pmu = hlist_entry_safe(node, typeof(*pmu), cpuhp.node);
>> +
>> + BUG_ON(!pmu->base.event_init);
>> +
>> + /* Select the first online CPU as a designated reader. */
>> + if (cpumask_empty(&xe_pmu_cpumask))
>> + cpumask_set_cpu(cpu, &xe_pmu_cpumask);
>> +
>> + return 0;
>> +}
>> +
>> +static int xe_pmu_cpu_offline(unsigned int cpu, struct hlist_node *node)
>> +{
>> + struct xe_pmu *pmu = hlist_entry_safe(node, typeof(*pmu), cpuhp.node);
>> + unsigned int target = xe_pmu_target_cpu;
>> +
>> + BUG_ON(!pmu->base.event_init);
>>
>>
>> nit but wondering if we should remove these two BUG_ON's (and save a couple
>> of checkpatch warnings even though the BUG_ON's are in i915) and just do
>> something like:
>>
>> if (!pmu->base.event_init)
>> return 0;
>>
>> The reason for the BUG_ON's seems to be that these functions can be called
>> after module_init but before probe.
>>
>> xe_pmu_cpu_online() doesn't depend on pmu at all so looks like the BUG_ON
>> can just be dropped?
>>
>> the xe_pmu_cpu_online/offline are not invoked when they are registered with
>> cpuhp_setup_state_multi, but rather when cpuhp_state_add_instance() is called
>> which is done post the PMU is initialized hence the check for BUG_ON.
> cpuhp_setup_state_multi is called at module_init
> time. cpuhp_state_add_instance is called from xe_pmu_register, i.e. during
> device probe when pmu->base.event_init is already initialized. Therefore
> seems even less reason to have the BUG_ON's.
that is true even, so will remove the BUG_ON.
>
> Just a few minor issues left now so I am hoping we can wrap this marathon
> review up soon :)
ya i'm waiting for the same :)
Thanks,
Aravind.
>
> Thanks.
> --
> Ashutosh
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