[PATCH RFC v4 13/16] drm, cgroup: Allow more aggressive memory reclaim
Kenny Ho
y2kenny at gmail.com
Thu Aug 29 14:07:47 UTC 2019
Thanks for the feedback Christian. I am still digging into this one.
Daniel suggested leveraging the Shrinker API for the functionality of this
commit in RFC v3 but I am still trying to figure it out how/if ttm fit with
shrinker (though the idea behind the shrinker API seems fairly
straightforward as far as I understand it currently.)
Regards,
Kenny
On Thu, Aug 29, 2019 at 3:08 AM Koenig, Christian <Christian.Koenig at amd.com>
wrote:
> Am 29.08.19 um 08:05 schrieb Kenny Ho:
> > Allow DRM TTM memory manager to register a work_struct, such that, when
> > a drmcgrp is under memory pressure, memory reclaiming can be triggered
> > immediately.
> >
> > Change-Id: I25ac04e2db9c19ff12652b88ebff18b44b2706d8
> > Signed-off-by: Kenny Ho <Kenny.Ho at amd.com>
> > ---
> > drivers/gpu/drm/ttm/ttm_bo.c | 49 +++++++++++++++++++++++++++++++++
> > include/drm/drm_cgroup.h | 16 +++++++++++
> > include/drm/ttm/ttm_bo_driver.h | 2 ++
> > kernel/cgroup/drm.c | 30 ++++++++++++++++++++
> > 4 files changed, 97 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> > index d7e3d3128ebb..72efae694b7e 100644
> > --- a/drivers/gpu/drm/ttm/ttm_bo.c
> > +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> > @@ -1590,6 +1590,46 @@ int ttm_bo_evict_mm(struct ttm_bo_device *bdev,
> unsigned mem_type)
> > }
> > EXPORT_SYMBOL(ttm_bo_evict_mm);
> >
> > +static void ttm_bo_reclaim_wq(struct work_struct *work)
> > +{
> > + struct ttm_operation_ctx ctx = {
> > + .interruptible = false,
> > + .no_wait_gpu = false,
> > + .flags = TTM_OPT_FLAG_FORCE_ALLOC
> > + };
> > + struct ttm_mem_type_manager *man =
> > + container_of(work, struct ttm_mem_type_manager, reclaim_wq);
> > + struct ttm_bo_device *bdev = man->bdev;
> > + struct dma_fence *fence;
> > + int mem_type;
> > + int ret;
> > +
> > + for (mem_type = 0; mem_type < TTM_NUM_MEM_TYPES; mem_type++)
> > + if (&bdev->man[mem_type] == man)
> > + break;
> > +
> > + WARN_ON(mem_type >= TTM_NUM_MEM_TYPES);
> > + if (mem_type >= TTM_NUM_MEM_TYPES)
> > + return;
> > +
> > + if (!drmcg_mem_pressure_scan(bdev, mem_type))
> > + return;
> > +
> > + ret = ttm_mem_evict_first(bdev, mem_type, NULL, &ctx, NULL);
> > + if (ret)
> > + return;
> > +
> > + spin_lock(&man->move_lock);
> > + fence = dma_fence_get(man->move);
> > + spin_unlock(&man->move_lock);
> > +
> > + if (fence) {
> > + ret = dma_fence_wait(fence, false);
> > + dma_fence_put(fence);
> > + }
>
> Why do you want to block for the fence here? That is a rather bad idea
> and would break pipe-lining.
>
> Apart from that I don't think we should put that into TTM.
>
> Instead drmcg_register_device_mm() should get a function pointer which
> is called from a work item when the group is under pressure.
>
> TTM can then provides the function which can be called, but the actually
> registration is job of the device and not TTM.
>
> Regards,
> Christian.
>
> > +
> > +}
> > +
> > int ttm_bo_init_mm(struct ttm_bo_device *bdev, unsigned type,
> > unsigned long p_size)
> > {
> > @@ -1624,6 +1664,13 @@ int ttm_bo_init_mm(struct ttm_bo_device *bdev,
> unsigned type,
> > INIT_LIST_HEAD(&man->lru[i]);
> > man->move = NULL;
> >
> > + pr_err("drmcg %p type %d\n", bdev->ddev, type);
> > +
> > + if (type <= TTM_PL_VRAM) {
> > + INIT_WORK(&man->reclaim_wq, ttm_bo_reclaim_wq);
> > + drmcg_register_device_mm(bdev->ddev, type,
> &man->reclaim_wq);
> > + }
> > +
> > return 0;
> > }
> > EXPORT_SYMBOL(ttm_bo_init_mm);
> > @@ -1701,6 +1748,8 @@ int ttm_bo_device_release(struct ttm_bo_device
> *bdev)
> > man = &bdev->man[i];
> > if (man->has_type) {
> > man->use_type = false;
> > + drmcg_unregister_device_mm(bdev->ddev, i);
> > + cancel_work_sync(&man->reclaim_wq);
> > if ((i != TTM_PL_SYSTEM) && ttm_bo_clean_mm(bdev,
> i)) {
> > ret = -EBUSY;
> > pr_err("DRM memory manager type %d is not
> clean\n",
> > diff --git a/include/drm/drm_cgroup.h b/include/drm/drm_cgroup.h
> > index c11df388fdf2..6d9707e1eb72 100644
> > --- a/include/drm/drm_cgroup.h
> > +++ b/include/drm/drm_cgroup.h
> > @@ -5,6 +5,7 @@
> > #define __DRM_CGROUP_H__
> >
> > #include <linux/cgroup_drm.h>
> > +#include <linux/workqueue.h>
> > #include <drm/ttm/ttm_bo_api.h>
> > #include <drm/ttm/ttm_bo_driver.h>
> >
> > @@ -25,12 +26,17 @@ struct drmcg_props {
> > s64 mem_bw_avg_bytes_per_us_default;
> >
> > s64 mem_highs_default[TTM_PL_PRIV+1];
> > +
> > + struct work_struct *mem_reclaim_wq[TTM_PL_PRIV];
> > };
> >
> > #ifdef CONFIG_CGROUP_DRM
> >
> > void drmcg_device_update(struct drm_device *device);
> > void drmcg_device_early_init(struct drm_device *device);
> > +void drmcg_register_device_mm(struct drm_device *dev, unsigned int type,
> > + struct work_struct *wq);
> > +void drmcg_unregister_device_mm(struct drm_device *dev, unsigned int
> type);
> > bool drmcg_try_chg_bo_alloc(struct drmcg *drmcg, struct drm_device
> *dev,
> > size_t size);
> > void drmcg_unchg_bo_alloc(struct drmcg *drmcg, struct drm_device *dev,
> > @@ -53,6 +59,16 @@ static inline void drmcg_device_early_init(struct
> drm_device *device)
> > {
> > }
> >
> > +static inline void drmcg_register_device_mm(struct drm_device *dev,
> > + unsigned int type, struct work_struct *wq)
> > +{
> > +}
> > +
> > +static inline void drmcg_unregister_device_mm(struct drm_device *dev,
> > + unsigned int type)
> > +{
> > +}
> > +
> > static inline void drmcg_try_chg_bo_alloc(struct drmcg *drmcg,
> > struct drm_device *dev, size_t size)
> > {
> > diff --git a/include/drm/ttm/ttm_bo_driver.h
> b/include/drm/ttm/ttm_bo_driver.h
> > index e1a805d65b83..529cef92bcf6 100644
> > --- a/include/drm/ttm/ttm_bo_driver.h
> > +++ b/include/drm/ttm/ttm_bo_driver.h
> > @@ -205,6 +205,8 @@ struct ttm_mem_type_manager {
> > * Protected by @move_lock.
> > */
> > struct dma_fence *move;
> > +
> > + struct work_struct reclaim_wq;
> > };
> >
> > /**
> > diff --git a/kernel/cgroup/drm.c b/kernel/cgroup/drm.c
> > index 04fb9a398740..0ea7f0619e25 100644
> > --- a/kernel/cgroup/drm.c
> > +++ b/kernel/cgroup/drm.c
> > @@ -804,6 +804,29 @@ void drmcg_device_early_init(struct drm_device *dev)
> > }
> > EXPORT_SYMBOL(drmcg_device_early_init);
> >
> > +void drmcg_register_device_mm(struct drm_device *dev, unsigned int type,
> > + struct work_struct *wq)
> > +{
> > + if (dev == NULL || type >= TTM_PL_PRIV)
> > + return;
> > +
> > + mutex_lock(&drmcg_mutex);
> > + dev->drmcg_props.mem_reclaim_wq[type] = wq;
> > + mutex_unlock(&drmcg_mutex);
> > +}
> > +EXPORT_SYMBOL(drmcg_register_device_mm);
> > +
> > +void drmcg_unregister_device_mm(struct drm_device *dev, unsigned int
> type)
> > +{
> > + if (dev == NULL || type >= TTM_PL_PRIV)
> > + return;
> > +
> > + mutex_lock(&drmcg_mutex);
> > + dev->drmcg_props.mem_reclaim_wq[type] = NULL;
> > + mutex_unlock(&drmcg_mutex);
> > +}
> > +EXPORT_SYMBOL(drmcg_unregister_device_mm);
> > +
> > /**
> > * drmcg_try_chg_bo_alloc - charge GEM buffer usage for a device and
> cgroup
> > * @drmcg: the DRM cgroup to be charged to
> > @@ -1013,6 +1036,13 @@ void drmcg_mem_track_move(struct
> ttm_buffer_object *old_bo, bool evict,
> >
> > ddr->mem_bw_stats[DRMCG_MEM_BW_ATTR_BYTE_CREDIT]
> > -= move_in_bytes;
> > +
> > + if (dev->drmcg_props.mem_reclaim_wq[new_mem_type]
> > + != NULL &&
> > + ddr->mem_stats[new_mem_type] >
> > + ddr->mem_highs[new_mem_type])
> > + schedule_work(dev->
> > + drmcg_props.mem_reclaim_wq[new_mem_type]);
> > }
> > mutex_unlock(&dev->drmcg_mutex);
> > }
>
>
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