Hi Michal,

On 25.06.2024 10:49, Nirmoy Das wrote:

GuC TLB invalidation depends on GuC to process the request from the CT
queue and then the real time to invalidate TLB. Add a function to return
overestimated possible time a TLB inval H2G might take which can be used
as timeout value for TLB invalidation wait time.

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/1622
Cc: Matthew Brost <matthew.brost@intel.com>
Suggested-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
---
 drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c |  2 +-
 drivers/gpu/drm/xe/xe_guc_ct.c              | 12 ++++++++++++
 drivers/gpu/drm/xe/xe_guc_ct.h              |  2 ++
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c b/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
index e1f1ccb01143..fa61070d6201 100644
--- a/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
+++ b/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
@@ -17,7 +17,7 @@
 #include "xe_trace.h"
 #include "regs/xe_guc_regs.h"
 
-#define TLB_TIMEOUT	(HZ / 4)
+#define TLB_TIMEOUT	xe_guc_tlb_timeout_jiffies()

if this is no longer a macro then maybe better get rid of it and use
function call directly ?

 
 static void xe_gt_tlb_fence_timeout(struct work_struct *work)
 {
diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
index b4137fe195a4..e30c0da86acc 100644
--- a/drivers/gpu/drm/xe/xe_guc_ct.c
+++ b/drivers/gpu/drm/xe/xe_guc_ct.c
@@ -112,6 +112,18 @@ ct_to_xe(struct xe_guc_ct *ct)
 #define CTB_G2H_BUFFER_SIZE	(4 * CTB_H2G_BUFFER_SIZE)
 #define G2H_ROOM_BUFFER_SIZE	(CTB_G2H_BUFFER_SIZE / 4)
 
+/**
+ * xe_guc_tlb_timeout_jiffies - Calculate the maximum time to process a tlb inval command
+ *
+ * This function computes the maximum time to process a tlb inval H2G commands
+ * in jiffies. A 4KB buffer full of commands takes a little over a second to process,

these numbers looks like from experiment - what commands did you use?
do we have SLA from the GuC for max processing time of any command?

This is from i915 which was added with https://patchwork.freedesktop.org/patch/563102/

+ * so this time is set to 2 seconds to be safe.

nit: missing "Return:" tag

+ */
+long xe_guc_tlb_timeout_jiffies(void)

this function doesn't fit into xe_guc_ct component at all

if you need to reflect CTB size in TLB timeout calculation then:

a) from xe_guc_ct export function that will tell you max number of
commands it can queue (or are already in the CTB queue)

b) in xe_guc_tlb import above function and apply additional timeout per
each H2G action in flight

Currently only information we have which is also validated /r-b-ed by GuC team is the above calculation.

I can export xe_guc_ct_max_queue_time_jiffies and use that in xe_guc_tlb so the function fits their component.

Regards,

Nirmoy

+{
+	return (CTB_H2G_BUFFER_SIZE * HZ) / SZ_2K;
+}
+
 static size_t guc_ct_size(void)
 {
 	return 2 * CTB_DESC_SIZE + CTB_H2G_BUFFER_SIZE +
diff --git a/drivers/gpu/drm/xe/xe_guc_ct.h b/drivers/gpu/drm/xe/xe_guc_ct.h
index 105bb8e99a8d..a9755574d6c9 100644
--- a/drivers/gpu/drm/xe/xe_guc_ct.h
+++ b/drivers/gpu/drm/xe/xe_guc_ct.h
@@ -64,4 +64,6 @@ xe_guc_ct_send_block_no_fail(struct xe_guc_ct *ct, const u32 *action, u32 len)
 	return xe_guc_ct_send_recv_no_fail(ct, action, len, NULL);
 }
 
+long xe_guc_tlb_timeout_jiffies(void);
+
 #endif