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Commit a309218a authored by Dan Williams's avatar Dan Williams
Browse files

ioat2,3: dynamically resize descriptor ring 



Increment the allocation order of the descriptor ring every time we run
out of descriptors up to a maximum of allocation order specified by the
module parameter 'ioat_max_alloc_order'.  After each idle period
decrement the allocation order to a minimum order of
'ioat_ring_alloc_order' (i.e. the default ring size, tunable as a module
parameter).

Signed-off-by: default avatarMaciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 09c8a5b8

drivers/dma/ioat/dma.h

+1 −0
Original line number Diff line number Diff line
@@ -88,6 +88,7 @@ struct ioat_chan_common { 
	#define IOAT_RESET_PENDING 2

	struct timer_list timer;

	#define COMPLETION_TIMEOUT msecs_to_jiffies(100)

	#define IDLE_TIMEOUT msecs_to_jiffies(2000)

	#define RESET_DELAY msecs_to_jiffies(100)

	struct ioatdma_device *device;

	dma_addr_t completion_dma;

drivers/dma/ioat/dma_v2.c

+184 −31
Original line number Diff line number Diff line
@@ -43,6 +43,10 @@ static int ioat_ring_alloc_order = 8; 
module_param(ioat_ring_alloc_order, int, 0644);

MODULE_PARM_DESC(ioat_ring_alloc_order,

		 "ioat2+: allocate 2^n descriptors per channel (default: n=8)");

static int ioat_ring_max_alloc_order = IOAT_MAX_ORDER;

module_param(ioat_ring_max_alloc_order, int, 0644);

MODULE_PARM_DESC(ioat_ring_max_alloc_order,

		 "ioat2+: upper limit for dynamic ring resizing (default: n=16)");



static void __ioat2_issue_pending(struct ioat2_dma_chan *ioat)

{
@@ -168,6 +172,7 @@ static void __cleanup(struct ioat2_dma_chan *ioat, unsigned long phys_complete) 
		dev_dbg(to_dev(chan), "%s: cancel completion timeout\n",

			__func__);

		clear_bit(IOAT_COMPLETION_PENDING, &chan->state);

		mod_timer(&chan->timer, jiffies + IDLE_TIMEOUT);

	}

}
@@ -253,6 +258,8 @@ static void ioat2_restart_channel(struct ioat2_dma_chan *ioat) 
	__restart_chan(ioat);

}



static bool reshape_ring(struct ioat2_dma_chan *ioat, int order);



static void ioat2_timer_event(unsigned long data)

{

	struct ioat2_dma_chan *ioat = (void *) data;
@@ -289,6 +296,23 @@ static void ioat2_timer_event(unsigned long data) 
			mod_timer(&chan->timer, jiffies + COMPLETION_TIMEOUT);

		}

		spin_unlock_bh(&ioat->ring_lock);

	} else {

		u16 active;



		/* if the ring is idle, empty, and oversized try to step

		 * down the size

		 */

		spin_lock_bh(&ioat->ring_lock);

		active = ioat2_ring_active(ioat);

		if (active == 0 && ioat->alloc_order > ioat_get_alloc_order())

			reshape_ring(ioat, ioat->alloc_order-1);

		spin_unlock_bh(&ioat->ring_lock);



		/* keep shrinking until we get back to our minimum

		 * default size

		 */

		if (ioat->alloc_order > ioat_get_alloc_order())

			mod_timer(&chan->timer, jiffies + IDLE_TIMEOUT);

	}

	spin_unlock_bh(&chan->cleanup_lock);

}
@@ -362,7 +386,7 @@ static dma_cookie_t ioat2_tx_submit_unlock(struct dma_async_tx_descriptor *tx) 
	return cookie;

}



static struct ioat_ring_ent *ioat2_alloc_ring_ent(struct dma_chan *chan)

static struct ioat_ring_ent *ioat2_alloc_ring_ent(struct dma_chan *chan, gfp_t flags)

{

	struct ioat_dma_descriptor *hw;

	struct ioat_ring_ent *desc;
@@ -370,12 +394,12 @@ static struct ioat_ring_ent *ioat2_alloc_ring_ent(struct dma_chan *chan) 
	dma_addr_t phys;



	dma = to_ioatdma_device(chan->device);

	hw = pci_pool_alloc(dma->dma_pool, GFP_KERNEL, &phys);

	hw = pci_pool_alloc(dma->dma_pool, flags, &phys);

	if (!hw)

		return NULL;

	memset(hw, 0, sizeof(*hw));



	desc = kzalloc(sizeof(*desc), GFP_KERNEL);

	desc = kzalloc(sizeof(*desc), flags);

	if (!desc) {

		pci_pool_free(dma->dma_pool, hw, phys);

		return NULL;
@@ -397,6 +421,42 @@ static void ioat2_free_ring_ent(struct ioat_ring_ent *desc, struct dma_chan *cha 
	kfree(desc);

}



static struct ioat_ring_ent **ioat2_alloc_ring(struct dma_chan *c, int order, gfp_t flags)

{

	struct ioat_ring_ent **ring;

	int descs = 1 << order;

	int i;



	if (order > ioat_get_max_alloc_order())

		return NULL;



	/* allocate the array to hold the software ring */

	ring = kcalloc(descs, sizeof(*ring), flags);

	if (!ring)

		return NULL;

	for (i = 0; i < descs; i++) {

		ring[i] = ioat2_alloc_ring_ent(c, flags);

		if (!ring[i]) {

			while (i--)

				ioat2_free_ring_ent(ring[i], c);

			kfree(ring);

			return NULL;

		}

		set_desc_id(ring[i], i);

	}



	/* link descs */

	for (i = 0; i < descs-1; i++) {

		struct ioat_ring_ent *next = ring[i+1];

		struct ioat_dma_descriptor *hw = ring[i]->hw;



		hw->next = next->txd.phys;

	}

	ring[i]->hw->next = ring[0]->txd.phys;



	return ring;

}



/* ioat2_alloc_chan_resources - allocate/initialize ioat2 descriptor ring

 * @chan: channel to be initialized

 */
@@ -406,8 +466,7 @@ static int ioat2_alloc_chan_resources(struct dma_chan *c) 
	struct ioat_chan_common *chan = &ioat->base;

	struct ioat_ring_ent **ring;

	u32 chanerr;

	int descs;

	int i;

	int order;



	/* have we already been set up? */

	if (ioat->ring)
@@ -435,32 +494,10 @@ static int ioat2_alloc_chan_resources(struct dma_chan *c) 
	writel(((u64) chan->completion_dma) >> 32,

	       chan->reg_base + IOAT_CHANCMP_OFFSET_HIGH);



	ioat->alloc_order = ioat_get_alloc_order();

	descs = 1 << ioat->alloc_order;



	/* allocate the array to hold the software ring */

	ring = kcalloc(descs, sizeof(*ring), GFP_KERNEL);

	order = ioat_get_alloc_order();

	ring = ioat2_alloc_ring(c, order, GFP_KERNEL);

	if (!ring)

		return -ENOMEM;

	for (i = 0; i < descs; i++) {

		ring[i] = ioat2_alloc_ring_ent(c);

		if (!ring[i]) {

			while (i--)

				ioat2_free_ring_ent(ring[i], c);

			kfree(ring);

			return -ENOMEM;

		}

		set_desc_id(ring[i], i);

	}



	/* link descs */

	for (i = 0; i < descs-1; i++) {

		struct ioat_ring_ent *next = ring[i+1];

		struct ioat_dma_descriptor *hw = ring[i]->hw;



		hw->next = next->txd.phys;

	}

	ring[i]->hw->next = ring[0]->txd.phys;



	spin_lock_bh(&ioat->ring_lock);

	ioat->ring = ring;
@@ -468,12 +505,120 @@ static int ioat2_alloc_chan_resources(struct dma_chan *c) 
	ioat->issued = 0;

	ioat->tail = 0;

	ioat->pending = 0;

	ioat->alloc_order = order;

	spin_unlock_bh(&ioat->ring_lock);



	tasklet_enable(&chan->cleanup_task);

	ioat2_start_null_desc(ioat);



	return descs;

	return 1 << ioat->alloc_order;

}



static bool reshape_ring(struct ioat2_dma_chan *ioat, int order)

{

	/* reshape differs from normal ring allocation in that we want

	 * to allocate a new software ring while only

	 * extending/truncating the hardware ring

	 */

	struct ioat_chan_common *chan = &ioat->base;

	struct dma_chan *c = &chan->common;

	const u16 curr_size = ioat2_ring_mask(ioat) + 1;

	const u16 active = ioat2_ring_active(ioat);

	const u16 new_size = 1 << order;

	struct ioat_ring_ent **ring;

	u16 i;



	if (order > ioat_get_max_alloc_order())

		return false;



	/* double check that we have at least 1 free descriptor */

	if (active == curr_size)

		return false;



	/* when shrinking, verify that we can hold the current active

	 * set in the new ring

	 */

	if (active >= new_size)

		return false;



	/* allocate the array to hold the software ring */

	ring = kcalloc(new_size, sizeof(*ring), GFP_NOWAIT);

	if (!ring)

		return false;



	/* allocate/trim descriptors as needed */

	if (new_size > curr_size) {

		/* copy current descriptors to the new ring */

		for (i = 0; i < curr_size; i++) {

			u16 curr_idx = (ioat->tail+i) & (curr_size-1);

			u16 new_idx = (ioat->tail+i) & (new_size-1);



			ring[new_idx] = ioat->ring[curr_idx];

			set_desc_id(ring[new_idx], new_idx);

		}



		/* add new descriptors to the ring */

		for (i = curr_size; i < new_size; i++) {

			u16 new_idx = (ioat->tail+i) & (new_size-1);



			ring[new_idx] = ioat2_alloc_ring_ent(c, GFP_NOWAIT);

			if (!ring[new_idx]) {

				while (i--) {

					u16 new_idx = (ioat->tail+i) & (new_size-1);



					ioat2_free_ring_ent(ring[new_idx], c);

				}

				kfree(ring);

				return false;

			}

			set_desc_id(ring[new_idx], new_idx);

		}



		/* hw link new descriptors */

		for (i = curr_size-1; i < new_size; i++) {

			u16 new_idx = (ioat->tail+i) & (new_size-1);

			struct ioat_ring_ent *next = ring[(new_idx+1) & (new_size-1)];

			struct ioat_dma_descriptor *hw = ring[new_idx]->hw;



			hw->next = next->txd.phys;

		}

	} else {

		struct ioat_dma_descriptor *hw;

		struct ioat_ring_ent *next;



		/* copy current descriptors to the new ring, dropping the

		 * removed descriptors

		 */

		for (i = 0; i < new_size; i++) {

			u16 curr_idx = (ioat->tail+i) & (curr_size-1);

			u16 new_idx = (ioat->tail+i) & (new_size-1);



			ring[new_idx] = ioat->ring[curr_idx];

			set_desc_id(ring[new_idx], new_idx);

		}



		/* free deleted descriptors */

		for (i = new_size; i < curr_size; i++) {

			struct ioat_ring_ent *ent;



			ent = ioat2_get_ring_ent(ioat, ioat->tail+i);

			ioat2_free_ring_ent(ent, c);

		}



		/* fix up hardware ring */

		hw = ring[(ioat->tail+new_size-1) & (new_size-1)]->hw;

		next = ring[(ioat->tail+new_size) & (new_size-1)];

		hw->next = next->txd.phys;

	}



	dev_dbg(to_dev(chan), "%s: allocated %d descriptors\n",

		__func__, new_size);



	kfree(ioat->ring);

	ioat->ring = ring;

	ioat->alloc_order = order;



	return true;

}



/**
@@ -487,7 +632,15 @@ static int ioat2_alloc_and_lock(u16 *idx, struct ioat2_dma_chan *ioat, int num_d 
	struct ioat_chan_common *chan = &ioat->base;



	spin_lock_bh(&ioat->ring_lock);

	if (unlikely(ioat2_ring_space(ioat) < num_descs)) {

	/* never allow the last descriptor to be consumed, we need at

	 * least one free at all times to allow for on-the-fly ring

	 * resizing.

	 */

	while (unlikely(ioat2_ring_space(ioat) <= num_descs)) {

		if (reshape_ring(ioat, ioat->alloc_order + 1) &&

		    ioat2_ring_space(ioat) > num_descs)

				break;



		if (printk_ratelimit())

			dev_dbg(to_dev(chan),

				"%s: ring full! num_descs: %d (%x:%x:%x)\n",

drivers/dma/ioat/dma_v2.h

+2 −0
Original line number Diff line number Diff line
@@ -37,6 +37,8 @@ extern int ioat_pending_level; 
#define IOAT_MAX_ORDER 16

#define ioat_get_alloc_order() \

	(min(ioat_ring_alloc_order, IOAT_MAX_ORDER))

#define ioat_get_max_alloc_order() \

	(min(ioat_ring_max_alloc_order, IOAT_MAX_ORDER))



/* struct ioat2_dma_chan - ioat v2 / v3 channel attributes

 * @base: common ioat channel parameters