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drm/xe: Defer buffer object shrinker write-backs and GPU waits

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When the xe buffer-object shrinker allows GPU waits and write-back,
(typically from kswapd), perform multiple passes, skipping
subsequent passes if the shrinker number of scanned objects target
is reached.

1) Without GPU waits and write-back
2) Without write-back
3) With both GPU-waits and write-back

This is to avoid stalls and costly write- and readbacks unless they
are really necessary.

v2:
- Don't test for scan completion twice. (Stuart Summers)
- Update tags.

Reported-by: melvyn <melvyn2@dnsense.pub>
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/5557
Cc: Summers Stuart <stuart.summers@intel.com>
Fixes: 00c8efc318 ("drm/xe: Add a shrinker for xe bos")
Cc: <stable@vger.kernel.org> # v6.15+
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Stuart Summers <stuart.summers@intel.com>
Link: https://lore.kernel.org/r/20250805074842.11359-1-thomas.hellstrom@linux.intel.com
This commit is contained in:
Thomas Hellström 2025-08-05 09:48:42 +02:00
parent 9b7ca35ed2
commit 80944d3341
1 changed files with 47 additions and 4 deletions
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51
drivers/gpu/drm/xe/xe_shrinker.c
View File

@ -54,10 +54,10 @@ xe_shrinker_mod_pages(struct xe_shrinker *shrinker, long shrinkable, long purgea
write_unlock(&shrinker->lock);
}
static s64 xe_shrinker_walk(struct xe_device *xe,
struct ttm_operation_ctx *ctx,
const struct xe_bo_shrink_flags flags,
unsigned long to_scan, unsigned long *scanned)
static s64 __xe_shrinker_walk(struct xe_device *xe,
struct ttm_operation_ctx *ctx,
const struct xe_bo_shrink_flags flags,
unsigned long to_scan, unsigned long *scanned)
{
unsigned int mem_type;
s64 freed = 0, lret;
@ -87,6 +87,48 @@ static s64 xe_shrinker_walk(struct xe_device *xe,
return freed;
}
/*
* Try shrinking idle objects without writeback first, then if not sufficient,
* try also non-idle objects and finally if that's not sufficient either,
* add writeback. This avoids stalls and explicit writebacks with light or
* moderate memory pressure.
*/
static s64 xe_shrinker_walk(struct xe_device *xe,
struct ttm_operation_ctx *ctx,
const struct xe_bo_shrink_flags flags,
unsigned long to_scan, unsigned long *scanned)
{
bool no_wait_gpu = true;
struct xe_bo_shrink_flags save_flags = flags;
s64 lret, freed;
swap(no_wait_gpu, ctx->no_wait_gpu);
save_flags.writeback = false;
lret = __xe_shrinker_walk(xe, ctx, save_flags, to_scan, scanned);
swap(no_wait_gpu, ctx->no_wait_gpu);
if (lret < 0 || *scanned >= to_scan)
return lret;
freed = lret;
if (!ctx->no_wait_gpu) {
lret = __xe_shrinker_walk(xe, ctx, save_flags, to_scan, scanned);
if (lret < 0)
return lret;
freed += lret;
if (*scanned >= to_scan)
return freed;
}
if (flags.writeback) {
lret = __xe_shrinker_walk(xe, ctx, flags, to_scan, scanned);
if (lret < 0)
return lret;
freed += lret;
}
return freed;
}
static unsigned long
xe_shrinker_count(struct shrinker *shrink, struct shrink_control *sc)
{
@ -193,6 +235,7 @@ static unsigned long xe_shrinker_scan(struct shrinker *shrink, struct shrink_con
runtime_pm = xe_shrinker_runtime_pm_get(shrinker, true, 0, can_backup);
shrink_flags.purge = false;
lret = xe_shrinker_walk(shrinker->xe, &ctx, shrink_flags,
nr_to_scan, &nr_scanned);
if (lret >= 0)