[PATCH 1/3] drm/i915/gvt: Use gtt_lock to protect gtt list
Du, Changbin
changbin.du at intel.com
Mon Apr 2 08:58:04 UTC 2018
On Sat, Mar 31, 2018 at 08:56:58AM +0800, Colin Xu wrote:
> From: Pei Zhang <pei.zhang at intel.com>
>
> The patch set splits out 3 small locks from the original big gvt lock:
> - gtt_lock is used to protect the gvt global gtt oos lists.
> - vgpu_lock protects per-vGPU data and logic, especially the vGPU
> trap emulation path.
> - sched_lock protects gvt scheudler structure, context schedule logic
> and vGPU's schedule data.
>
> GVT gtt contains 2 oos list, and one global mm list. Use a special
> gvt->gtt_lock to protect those 3 lists.
>
> v4:
> - Rebase to latest gvt-staging.
> - Add missing protection when access list in clean_spt_oos().
> - Fix locked recursive call of detach_oos_page when cleanup. (zhenyu)
> v3: Update to latest code base.
> v2: use gtt_lock to cover correct scope in ppgtt_allocate_oos_page().
>
> Performance comparison on Kabylake platform.
> - Configuration:
> Host: Ubuntu 16.04.
> Guest 1 & 2: Ubuntu 16.04.
>
> glmark2 score comparison:
> - Configuration:
> Host: glxgears.
> Guests: glmark2.
> +--------------------------------+-----------------+
> | Setup | glmark2 score |
> +--------------------------------+-----------------+
> | unified lock, iommu=on | 58~62 (avg. 60) |
> +--------------------------------+-----------------+
> | unified lock, iommu=igfx_off | 57~61 (avg. 59) |
> +--------------------------------+-----------------+
> | per-logic lock, iommu=on | 60~68 (avg. 64) |
> +--------------------------------+-----------------+
> | per-logic lock, iommu=igfx_off | 61~67 (avg. 64) |
> +--------------------------------+-----------------+
>
> lock_stat comparison:
> - Configuration:
> Stop lock stat immediately after boot up.
> Boot 2 VM Guests.
> Run glmark2 in guests.
> Start perf lock_stat for 20 seconds and stop again.
> - Legend: c - contentions; w - waittime-avg
> +------------+-----------------+-----------+---------------+------------+
> | | gvt_lock |sched_lock | vgpu_lock | gtt_lock |
> + lock type; +-----------------+-----------+---------------+------------+
> | iommu set | c | w | c | w | c | w | c | w |
> +------------+-------+---------+----+------+------+--------+-----+------+
> | unified; | 20697 | 839 |N/A | N/A | N/A | N/A | N/A | N/A |
> | on | | | | | | | | |
> +------------+-------+---------+----+------+------+--------+-----+------+
> | unified; | 21838 | 658.15 |N/A | N/A | N/A | N/A | N/A | N/A |
> | igfx_off | | | | | | | | |
> +------------+-------+---------+----+------+------+--------+-----+------+
> | per-logic; | 1553 | 1599.96 |9458|429.97| 5846 | 274.33 | 0 | 0.00 |
> | on | | | | | | | | |
> +------------+-------+---------+----+------+------+--------+-----+------+
> | per-logic; | 1911 | 1678.32 |8335|445.16| 5451 | 244.80 | 0 | 0.00 |
> | igfx_off | | | | | | | | |
> +------------+-------+---------+----+------+------+--------+-----+------+
>
Colin,
Seeing above data, seems this new gtt_lock is not necessoray. The scope of
gtt_lock has already covered by gvt_lock. Because
intel_vgpu_page_track_handler() has acquired the gvt lock. Besides,
intel_vgpu_page_track_handler() should acquire vpu_lock instead of gvt_lock.
Thanks!
> Signed-off-by: Pei Zhang <pei.zhang at intel.com>
> Signed-off-by: Colin Xu <colin.xu at intel.com>
> ---
> drivers/gpu/drm/i915/gvt/gtt.c | 38 +++++++++++++++++++++++++++-----------
> drivers/gpu/drm/i915/gvt/gvt.c | 1 +
> drivers/gpu/drm/i915/gvt/gvt.h | 2 ++
> 3 files changed, 30 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
> index 78e55aafc8bc..f78b4b9c10a8 100644
> --- a/drivers/gpu/drm/i915/gvt/gtt.c
> +++ b/drivers/gpu/drm/i915/gvt/gtt.c
> @@ -639,7 +639,7 @@ static void free_spt(struct intel_vgpu_ppgtt_spt *spt)
> kfree(spt);
> }
>
> -static int detach_oos_page(struct intel_vgpu *vgpu,
> +static int detach_oos_page_locked(struct intel_vgpu *vgpu,
> struct intel_vgpu_oos_page *oos_page);
>
> static void ppgtt_free_spt(struct intel_vgpu_ppgtt_spt *spt)
> @@ -653,8 +653,11 @@ static void ppgtt_free_spt(struct intel_vgpu_ppgtt_spt *spt)
>
> radix_tree_delete(&spt->vgpu->gtt.spt_tree, spt->shadow_page.mfn);
>
> - if (spt->guest_page.oos_page)
> - detach_oos_page(spt->vgpu, spt->guest_page.oos_page);
> + if (spt->guest_page.oos_page) {
> + mutex_lock(&spt->vgpu->gvt->gtt_lock);
> + detach_oos_page_locked(spt->vgpu, spt->guest_page.oos_page);
> + mutex_unlock(&spt->vgpu->gvt->gtt_lock);
> + }
>
> intel_vgpu_unregister_page_track(spt->vgpu, spt->guest_page.gfn);
>
> @@ -1150,7 +1153,7 @@ static int sync_oos_page(struct intel_vgpu *vgpu,
> return 0;
> }
>
> -static int detach_oos_page(struct intel_vgpu *vgpu,
> +static int detach_oos_page_locked(struct intel_vgpu *vgpu,
> struct intel_vgpu_oos_page *oos_page)
> {
> struct intel_gvt *gvt = vgpu->gvt;
> @@ -1169,7 +1172,7 @@ static int detach_oos_page(struct intel_vgpu *vgpu,
> return 0;
> }
>
> -static int attach_oos_page(struct intel_vgpu_oos_page *oos_page,
> +static int attach_oos_page_locked(struct intel_vgpu_oos_page *oos_page,
> struct intel_vgpu_ppgtt_spt *spt)
> {
> struct intel_gvt *gvt = spt->vgpu->gvt;
> @@ -1216,19 +1219,23 @@ static int ppgtt_allocate_oos_page(struct intel_vgpu_ppgtt_spt *spt)
>
> WARN(oos_page, "shadow PPGTT page has already has a oos page\n");
>
> + mutex_lock(&gvt->gtt_lock);
> if (list_empty(>t->oos_page_free_list_head)) {
> oos_page = container_of(gtt->oos_page_use_list_head.next,
> struct intel_vgpu_oos_page, list);
> ret = ppgtt_set_guest_page_sync(oos_page->spt);
> if (ret)
> - return ret;
> - ret = detach_oos_page(spt->vgpu, oos_page);
> + goto out;
> + ret = detach_oos_page_locked(spt->vgpu, oos_page);
> if (ret)
> - return ret;
> + goto out;
> } else
> oos_page = container_of(gtt->oos_page_free_list_head.next,
> struct intel_vgpu_oos_page, list);
> - return attach_oos_page(oos_page, spt);
> + ret = attach_oos_page_locked(oos_page, spt);
> +out:
> + mutex_unlock(&gvt->gtt_lock);
> + return ret;
> }
>
> static int ppgtt_set_guest_page_oos(struct intel_vgpu_ppgtt_spt *spt)
> @@ -1653,8 +1660,10 @@ int intel_vgpu_pin_mm(struct intel_vgpu_mm *mm)
> if (ret)
> return ret;
>
> + mutex_lock(&mm->vgpu->gvt->gtt_lock);
> list_move_tail(&mm->ppgtt_mm.lru_list,
> &mm->vgpu->gvt->gtt.ppgtt_mm_lru_list_head);
> + mutex_unlock(&mm->vgpu->gvt->gtt_lock);
>
> }
>
> @@ -1663,9 +1672,11 @@ int intel_vgpu_pin_mm(struct intel_vgpu_mm *mm)
>
> static int reclaim_one_ppgtt_mm(struct intel_gvt *gvt)
> {
> + int ret = 0;
> struct intel_vgpu_mm *mm;
> struct list_head *pos, *n;
>
> + mutex_lock(&gvt->gtt_lock);
> list_for_each_safe(pos, n, &gvt->gtt.ppgtt_mm_lru_list_head) {
> mm = container_of(pos, struct intel_vgpu_mm, ppgtt_mm.lru_list);
>
> @@ -1674,9 +1685,11 @@ static int reclaim_one_ppgtt_mm(struct intel_gvt *gvt)
>
> list_del_init(&mm->ppgtt_mm.lru_list);
> invalidate_ppgtt_mm(mm);
> - return 1;
> + ret = 1;
> }
> - return 0;
> + mutex_unlock(&gvt->gtt_lock);
> +
> + return ret;
> }
>
> /*
> @@ -2109,6 +2122,8 @@ static void clean_spt_oos(struct intel_gvt *gvt)
> struct list_head *pos, *n;
> struct intel_vgpu_oos_page *oos_page;
>
> + mutex_lock(&gvt->gtt_lock);
> +
> WARN(!list_empty(>t->oos_page_use_list_head),
> "someone is still using oos page\n");
>
> @@ -2117,6 +2132,7 @@ static void clean_spt_oos(struct intel_gvt *gvt)
> list_del(&oos_page->list);
> kfree(oos_page);
> }
> + mutex_unlock(&gvt->gtt_lock);
> }
>
> static int setup_spt_oos(struct intel_gvt *gvt)
> diff --git a/drivers/gpu/drm/i915/gvt/gvt.c b/drivers/gpu/drm/i915/gvt/gvt.c
> index 61bd14fcb649..91c37f115780 100644
> --- a/drivers/gpu/drm/i915/gvt/gvt.c
> +++ b/drivers/gpu/drm/i915/gvt/gvt.c
> @@ -379,6 +379,7 @@ int intel_gvt_init_device(struct drm_i915_private *dev_priv)
> idr_init(&gvt->vgpu_idr);
> spin_lock_init(&gvt->scheduler.mmio_context_lock);
> mutex_init(&gvt->lock);
> + mutex_init(&gvt->gtt_lock);
> gvt->dev_priv = dev_priv;
>
> init_device_info(gvt);
> diff --git a/drivers/gpu/drm/i915/gvt/gvt.h b/drivers/gpu/drm/i915/gvt/gvt.h
> index efacd8abbedc..01fe294eab74 100644
> --- a/drivers/gpu/drm/i915/gvt/gvt.h
> +++ b/drivers/gpu/drm/i915/gvt/gvt.h
> @@ -295,6 +295,8 @@ struct intel_vgpu_type {
>
> struct intel_gvt {
> struct mutex lock;
> + struct mutex gtt_lock;
> +
> struct drm_i915_private *dev_priv;
> struct idr vgpu_idr; /* vGPU IDR pool */
>
> --
> 2.16.3
>
> _______________________________________________
> intel-gvt-dev mailing list
> intel-gvt-dev at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gvt-dev
--
Thanks,
Changbin Du
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