From: Chris Wilson <chris@chris-wilson.co.uk>
To: Xiaolin Zhang <xiaolin.zhang@intel.com>,
intel-gfx@lists.freedesktop.org,
intel-gvt-dev@lists.freedesktop.org
Cc: zhenyu.z.wang@intel.com, hang.yuan@intel.com, zhiyuan.lv@intel.com
Subject: Re: [PATCH v4 4/8] drm/i915: vgpu context submission pv optimization
Date: Fri, 29 Mar 2019 19:14:04 +0000 [thread overview]
Message-ID: <155388684392.24691.4103217140609550300@skylake-alporthouse-com> (raw)
In-Reply-To: <1553866364-111114-5-git-send-email-xiaolin.zhang@intel.com>
Quoting Xiaolin Zhang (2019-03-29 13:32:40)
> + spin_lock(&engine->i915->vgpu.shared_page_lock);
> + shared_page->ring_id = engine->id;
> + for (n = 0; n < execlists_num_ports(execlists); n++)
> + shared_page->descs[n] = descs[n];
> +
> + __raw_i915_write32(uncore, vgtif_reg(g2v_notify),
> + VGT_G2V_PV_SUBMISSION);
There's no serialisation with the consumer here. The
shared_page->descs[] will be clobbered by a second engine before they
are read by pv. There should be a wait-for-ack here, or separate
channels for each engine. In execlists, we avoid this by not dequeuing
until after we get a response/ack from HW.
Preemption? I guess preemption was turned off, or else you have to worry
about the same engine overwriting the desc[] (if no ack).
-Chris
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next prev parent reply other threads:[~2019-03-29 19:14 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-29 13:32 [PATCH v4 0/8] i915 vgpu PV to improve vgpu performance Xiaolin Zhang
2019-03-29 5:00 ` ✗ Fi.CI.BAT: failure for " Patchwork
2019-03-29 13:32 ` [PATCH v4 1/8] drm/i915: introduced vgpu pv capability Xiaolin Zhang
2019-03-29 13:32 ` [PATCH v4 2/8] drm/i915: vgpu shared memory setup for pv optimization Xiaolin Zhang
2019-03-29 13:32 ` [PATCH v4 3/8] drm/i915: vgpu ppgtt update " Xiaolin Zhang
2019-03-29 13:32 ` [PATCH v4 4/8] drm/i915: vgpu context submission " Xiaolin Zhang
2019-03-29 7:15 ` Chris Wilson
2019-03-29 15:40 ` Chris Wilson
2019-04-11 5:46 ` Zhang, Xiaolin
2019-03-29 19:14 ` Chris Wilson [this message]
2019-04-11 5:49 ` Zhang, Xiaolin
2019-03-29 13:32 ` [PATCH v4 5/8] drm/i915/gvt: GVTg handle pv_caps PVINFO register Xiaolin Zhang
2019-03-29 13:32 ` [PATCH v4 6/8] drm/i915/gvt: GVTg handle shared_page setup Xiaolin Zhang
2019-03-29 13:32 ` [PATCH v4 7/8] drm/i915/gvt: GVTg support ppgtt pv optimization Xiaolin Zhang
2019-03-29 13:32 ` [PATCH v4 8/8] drm/i915/gvt: GVTg support context submission " Xiaolin Zhang
2019-03-29 16:05 ` [PATCH v4 0/8] i915 vgpu PV to improve vgpu performance Chris Wilson
2019-04-11 5:54 ` Zhang, Xiaolin
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