[PATCH 2/2] drm/xe: Use topology to determine page fault queue size
Summers, Stuart
stuart.summers at intel.com
Tue Jun 25 17:38:09 UTC 2024
On Mon, 2024-06-10 at 22:32 +0000, Matthew Brost wrote:
> On Mon, Jun 10, 2024 at 08:33:00PM +0000, Stuart Summers wrote:
> > Currently the page fault queue size is hard coded. However
> > the hardware supports faulting for each EU and each CS.
> > For some applications running on hardware with a large
> > number of EUs and CSs, this can result in an overflow of
> > the page fault queue.
> >
> > Add a small calculation to determine the page fault queue
> > size based on the number of EUs and CSs in the platform as
> > detmined by fuses.
> >
>
> This math will also be needed when determining the G2H queue size as
> page faults get sunk to that queue first before being copied to this
> secondary queue.
Ok let me look..
>
> > Signed-off-by: Stuart Summers <stuart.summers at intel.com>
> > ---
> > drivers/gpu/drm/xe/xe_gt_pagefault.c | 49 +++++++++++++++++++++---
> > ----
> > drivers/gpu/drm/xe/xe_gt_types.h | 4 +--
> > 2 files changed, 39 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/xe/xe_gt_pagefault.c
> > b/drivers/gpu/drm/xe/xe_gt_pagefault.c
> > index 3858c8e0b707..5565732e79e9 100644
> > --- a/drivers/gpu/drm/xe/xe_gt_pagefault.c
> > +++ b/drivers/gpu/drm/xe/xe_gt_pagefault.c
> > @@ -287,7 +287,7 @@ static bool get_pagefault(struct pf_queue
> > *pf_queue, struct pagefault *pf)
> > PFD_VIRTUAL_ADDR_LO_SHIFT;
> >
> > pf_queue->tail = (pf_queue->tail + PF_MSG_LEN_DW) %
> > - PF_QUEUE_NUM_DW;
> > + pf_queue->pf_queue_num_dw;
> > ret = true;
> > }
> > spin_unlock_irq(&pf_queue->lock);
> > @@ -299,7 +299,8 @@ static bool pf_queue_full(struct pf_queue
> > *pf_queue)
> > {
> > lockdep_assert_held(&pf_queue->lock);
> >
> > - return CIRC_SPACE(pf_queue->head, pf_queue->tail,
> > PF_QUEUE_NUM_DW) <=
> > + return CIRC_SPACE(pf_queue->head, pf_queue->tail,
> > + pf_queue->pf_queue_num_dw) <=
>
> I don't think the <= PF_MSG_LEN_DW is needed.
I thought the idea here was to make sure the max space we might
possibly need (PF_MSG_LEN_DW) is available in the rest of the queue
(CIRC_SPACE...). Isn't this exactly what we want to check?
>
> > PF_MSG_LEN_DW;
> > }
> >
> > @@ -312,11 +313,6 @@ int xe_guc_pagefault_handler(struct xe_guc
> > *guc, u32 *msg, u32 len)
> > u32 asid;
> > bool full;
> >
> > - /*
> > - * The below logic doesn't work unless PF_QUEUE_NUM_DW %
> > PF_MSG_LEN_DW == 0
> > - */
> > - BUILD_BUG_ON(PF_QUEUE_NUM_DW % PF_MSG_LEN_DW);
> > -
>
> So here I'd add:
> xe_gt_assert(gt, !(pf_queue->pf_queue_num_dw %PF_QUEUE_NUM_DW);
Makes sense.
>
> > if (unlikely(len != PF_MSG_LEN_DW))
> > return -EPROTO;
> >
> > @@ -327,7 +323,8 @@ int xe_guc_pagefault_handler(struct xe_guc
> > *guc, u32 *msg, u32 len)
> > full = pf_queue_full(pf_queue);
> > if (!full) {
> > memcpy(pf_queue->data + pf_queue->head, msg, len *
> > sizeof(u32));
> > - pf_queue->head = (pf_queue->head + len) %
> > PF_QUEUE_NUM_DW;
> > + pf_queue->head = (pf_queue->head + len) %
> > + pf_queue->pf_queue_num_dw;
> > queue_work(gt->usm.pf_wq, &pf_queue->worker);
> > } else {
> > drm_warn(&xe->drm, "PF Queue full, shouldn't be
> > possible");
> > @@ -382,18 +379,42 @@ static void pf_queue_work_func(struct
> > work_struct *w)
> >
> > static void acc_queue_work_func(struct work_struct *w);
> >
> > +static int xe_alloc_pf_queue(struct xe_gt *gt, struct pf_queue
> > *pf_queue)
> > +{
> > + xe_dss_mask_t all_dss;
> > + int num_dss, num_eus;
> > +
> > + bitmap_or(all_dss, gt->fuse_topo.g_dss_mask, gt-
> > >fuse_topo.c_dss_mask,
> > + XE_MAX_DSS_FUSE_BITS);
> > +
> > + num_dss = bitmap_weight(all_dss, XE_MAX_DSS_FUSE_BITS);
> > + num_eus = bitmap_weight(gt->fuse_topo.eu_mask_per_dss,
> > + XE_MAX_EU_FUSE_BITS) * num_dss;
> > +
> > + /* user can issue separate page faults per EU and per CS */
> > + pf_queue->pf_queue_num_dw =
> > + ALIGN(num_eus + XE_NUM_HW_ENGINES, PF_MSG_LEN_DW);
> > +
> > + pf_queue->gt = gt;
> > + pf_queue->data = kzalloc(pf_queue->pf_queue_num_dw,
> > GFP_KERNEL);
> > + spin_lock_init(&pf_queue->lock);
> > + INIT_WORK(&pf_queue->worker, pf_queue_work_func);
> > +
> > + return 0;
> > +}
> > +
> > int xe_gt_pagefault_init(struct xe_gt *gt)
> > {
> > struct xe_device *xe = gt_to_xe(gt);
> > - int i;
> > + int i, ret = 0;
> >
> > if (!xe->info.has_usm)
> > return 0;
> >
> > for (i = 0; i < NUM_PF_QUEUE; ++i) {
> > - gt->usm.pf_queue[i].gt = gt;
> > - spin_lock_init(>->usm.pf_queue[i].lock);
> > - INIT_WORK(>->usm.pf_queue[i].worker,
> > pf_queue_work_func);
> > + ret = xe_alloc_pf_queue(gt, >->usm.pf_queue[i]);
> > + if (ret)
> > + return ret;
> > }
> > for (i = 0; i < NUM_ACC_QUEUE; ++i) {
> > gt->usm.acc_queue[i].gt = gt;
> > @@ -418,12 +439,16 @@ int xe_gt_pagefault_init(struct xe_gt *gt)
> > void xe_gt_pagefault_fini(struct xe_gt *gt)
> > {
> > struct xe_device *xe = gt_to_xe(gt);
> > + int i;
> >
> > if (!xe->info.has_usm)
> > return;
> >
> > destroy_workqueue(gt->usm.acc_wq);
> > destroy_workqueue(gt->usm.pf_wq);
> > +
> > + for (i = 0; i < NUM_PF_QUEUE; ++i)
> > + kfree(gt->usm.pf_queue[i].data);
> > }
> >
> > void xe_gt_pagefault_reset(struct xe_gt *gt)
> > diff --git a/drivers/gpu/drm/xe/xe_gt_types.h
> > b/drivers/gpu/drm/xe/xe_gt_types.h
> > index 10a9a9529377..c40b9c1b5fec 100644
> > --- a/drivers/gpu/drm/xe/xe_gt_types.h
> > +++ b/drivers/gpu/drm/xe/xe_gt_types.h
> > @@ -232,9 +232,9 @@ struct xe_gt {
> > struct pf_queue {
> > /** @usm.pf_queue.gt: back pointer to GT */
> > struct xe_gt *gt;
> > -#define PF_QUEUE_NUM_DW 128
> > /** @usm.pf_queue.data: data in the page
> > fault queue */
> > - u32 data[PF_QUEUE_NUM_DW];
> > + u32 *data;
>
> Kernel doc.
Ok.
Thanks,
Stuart
>
> > + u32 pf_queue_num_dw;
> > /**
> > * @usm.pf_queue.tail: tail pointer in DWs
> > for page fault queue,
> > * moved by worker which processes faults
> > (consumer).
> > --
> > 2.34.1
> >
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