From 074cc47679f8b0931d7d5384e95822d82768f149 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Sat, 1 May 2010 15:22:55 -0700 Subject: ioat2,3: convert to producer/consumer locking Use separate locks for the descriptor prep (producer) and descriptor cleanup (consumer) paths. Allows the producer path to run concurrently with the cleanup path. Inspired by Documentation/circular-buffer.txt. Cc: David Howells Cc: Paul E. McKenney Cc: Maciej Sosnowski Signed-off-by: Dan Williams --- drivers/dma/ioat/dma_v2.c | 182 +++++++++++++++++++++++----------------------- 1 file changed, 93 insertions(+), 89 deletions(-) (limited to 'drivers/dma/ioat/dma_v2.c') diff --git a/drivers/dma/ioat/dma_v2.c b/drivers/dma/ioat/dma_v2.c index b6699a350989..e75d0299bb82 100644 --- a/drivers/dma/ioat/dma_v2.c +++ b/drivers/dma/ioat/dma_v2.c @@ -56,8 +56,6 @@ void __ioat2_issue_pending(struct ioat2_dma_chan *ioat) ioat->dmacount += ioat2_ring_pending(ioat); ioat->issued = ioat->head; - /* make descriptor updates globally visible before notifying channel */ - wmb(); writew(ioat->dmacount, chan->reg_base + IOAT_CHAN_DMACOUNT_OFFSET); dev_dbg(to_dev(chan), "%s: head: %#x tail: %#x issued: %#x count: %#x\n", @@ -69,9 +67,9 @@ void ioat2_issue_pending(struct dma_chan *c) struct ioat2_dma_chan *ioat = to_ioat2_chan(c); if (ioat2_ring_pending(ioat)) { - spin_lock_bh(&ioat->ring_lock); + spin_lock_bh(&ioat->prep_lock); __ioat2_issue_pending(ioat); - spin_unlock_bh(&ioat->ring_lock); + spin_unlock_bh(&ioat->prep_lock); } } @@ -80,7 +78,7 @@ void ioat2_issue_pending(struct dma_chan *c) * @ioat: ioat2+ channel * * Check if the number of unsubmitted descriptors has exceeded the - * watermark. Called with ring_lock held + * watermark. Called with prep_lock held */ static void ioat2_update_pending(struct ioat2_dma_chan *ioat) { @@ -92,7 +90,6 @@ static void __ioat2_start_null_desc(struct ioat2_dma_chan *ioat) { struct ioat_ring_ent *desc; struct ioat_dma_descriptor *hw; - int idx; if (ioat2_ring_space(ioat) < 1) { dev_err(to_dev(&ioat->base), @@ -102,8 +99,7 @@ static void __ioat2_start_null_desc(struct ioat2_dma_chan *ioat) dev_dbg(to_dev(&ioat->base), "%s: head: %#x tail: %#x issued: %#x\n", __func__, ioat->head, ioat->tail, ioat->issued); - idx = ioat2_desc_alloc(ioat, 1); - desc = ioat2_get_ring_ent(ioat, idx); + desc = ioat2_get_ring_ent(ioat, ioat->head); hw = desc->hw; hw->ctl = 0; @@ -117,14 +113,16 @@ static void __ioat2_start_null_desc(struct ioat2_dma_chan *ioat) async_tx_ack(&desc->txd); ioat2_set_chainaddr(ioat, desc->txd.phys); dump_desc_dbg(ioat, desc); + wmb(); + ioat->head += 1; __ioat2_issue_pending(ioat); } static void ioat2_start_null_desc(struct ioat2_dma_chan *ioat) { - spin_lock_bh(&ioat->ring_lock); + spin_lock_bh(&ioat->prep_lock); __ioat2_start_null_desc(ioat); - spin_unlock_bh(&ioat->ring_lock); + spin_unlock_bh(&ioat->prep_lock); } static void __cleanup(struct ioat2_dma_chan *ioat, unsigned long phys_complete) @@ -134,15 +132,16 @@ static void __cleanup(struct ioat2_dma_chan *ioat, unsigned long phys_complete) struct ioat_ring_ent *desc; bool seen_current = false; u16 active; - int i; + int idx = ioat->tail, i; dev_dbg(to_dev(chan), "%s: head: %#x tail: %#x issued: %#x\n", __func__, ioat->head, ioat->tail, ioat->issued); active = ioat2_ring_active(ioat); for (i = 0; i < active && !seen_current; i++) { - prefetch(ioat2_get_ring_ent(ioat, ioat->tail + i + 1)); - desc = ioat2_get_ring_ent(ioat, ioat->tail + i); + smp_read_barrier_depends(); + prefetch(ioat2_get_ring_ent(ioat, idx + i + 1)); + desc = ioat2_get_ring_ent(ioat, idx + i); tx = &desc->txd; dump_desc_dbg(ioat, desc); if (tx->cookie) { @@ -158,11 +157,12 @@ static void __cleanup(struct ioat2_dma_chan *ioat, unsigned long phys_complete) if (tx->phys == phys_complete) seen_current = true; } - ioat->tail += i; + smp_mb(); /* finish all descriptor reads before incrementing tail */ + ioat->tail = idx + i; BUG_ON(active && !seen_current); /* no active descs have written a completion? */ chan->last_completion = phys_complete; - if (ioat->head == ioat->tail) { + if (active - i == 0) { dev_dbg(to_dev(chan), "%s: cancel completion timeout\n", __func__); clear_bit(IOAT_COMPLETION_PENDING, &chan->state); @@ -179,24 +179,9 @@ static void ioat2_cleanup(struct ioat2_dma_chan *ioat) struct ioat_chan_common *chan = &ioat->base; unsigned long phys_complete; - prefetch(chan->completion); - - if (!spin_trylock_bh(&chan->cleanup_lock)) - return; - - if (!ioat_cleanup_preamble(chan, &phys_complete)) { - spin_unlock_bh(&chan->cleanup_lock); - return; - } - - if (!spin_trylock_bh(&ioat->ring_lock)) { - spin_unlock_bh(&chan->cleanup_lock); - return; - } - - __cleanup(ioat, phys_complete); - - spin_unlock_bh(&ioat->ring_lock); + spin_lock_bh(&chan->cleanup_lock); + if (ioat_cleanup_preamble(chan, &phys_complete)) + __cleanup(ioat, phys_complete); spin_unlock_bh(&chan->cleanup_lock); } @@ -287,12 +272,10 @@ void ioat2_timer_event(unsigned long data) struct ioat2_dma_chan *ioat = to_ioat2_chan((void *) data); struct ioat_chan_common *chan = &ioat->base; - spin_lock_bh(&chan->cleanup_lock); if (test_bit(IOAT_COMPLETION_PENDING, &chan->state)) { unsigned long phys_complete; u64 status; - spin_lock_bh(&ioat->ring_lock); status = ioat_chansts(chan); /* when halted due to errors check for channel @@ -311,26 +294,31 @@ void ioat2_timer_event(unsigned long data) * acknowledged a pending completion once, then be more * forceful with a restart */ - if (ioat_cleanup_preamble(chan, &phys_complete)) + spin_lock_bh(&chan->cleanup_lock); + if (ioat_cleanup_preamble(chan, &phys_complete)) { __cleanup(ioat, phys_complete); - else if (test_bit(IOAT_COMPLETION_ACK, &chan->state)) + } else if (test_bit(IOAT_COMPLETION_ACK, &chan->state)) { + spin_lock_bh(&ioat->prep_lock); ioat2_restart_channel(ioat); - else { + spin_unlock_bh(&ioat->prep_lock); + } else { set_bit(IOAT_COMPLETION_ACK, &chan->state); mod_timer(&chan->timer, jiffies + COMPLETION_TIMEOUT); } - spin_unlock_bh(&ioat->ring_lock); + spin_unlock_bh(&chan->cleanup_lock); } else { u16 active; /* if the ring is idle, empty, and oversized try to step * down the size */ - spin_lock_bh(&ioat->ring_lock); + spin_lock_bh(&chan->cleanup_lock); + spin_lock_bh(&ioat->prep_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); + spin_unlock_bh(&ioat->prep_lock); + spin_unlock_bh(&chan->cleanup_lock); /* keep shrinking until we get back to our minimum * default size @@ -338,7 +326,6 @@ void ioat2_timer_event(unsigned long data) if (ioat->alloc_order > ioat_get_alloc_order()) mod_timer(&chan->timer, jiffies + IDLE_TIMEOUT); } - spin_unlock_bh(&chan->cleanup_lock); } static int ioat2_reset_hw(struct ioat_chan_common *chan) @@ -392,7 +379,7 @@ int ioat2_enumerate_channels(struct ioatdma_device *device) ioat_init_channel(device, &ioat->base, i); ioat->xfercap_log = xfercap_log; - spin_lock_init(&ioat->ring_lock); + spin_lock_init(&ioat->prep_lock); if (device->reset_hw(&ioat->base)) { i = 0; break; @@ -418,8 +405,17 @@ static dma_cookie_t ioat2_tx_submit_unlock(struct dma_async_tx_descriptor *tx) if (!test_and_set_bit(IOAT_COMPLETION_PENDING, &chan->state)) mod_timer(&chan->timer, jiffies + COMPLETION_TIMEOUT); + + /* make descriptor updates visible before advancing ioat->head, + * this is purposefully not smp_wmb() since we are also + * publishing the descriptor updates to a dma device + */ + wmb(); + + ioat->head += ioat->produce; + ioat2_update_pending(ioat); - spin_unlock_bh(&ioat->ring_lock); + spin_unlock_bh(&ioat->prep_lock); return cookie; } @@ -531,13 +527,15 @@ int ioat2_alloc_chan_resources(struct dma_chan *c) if (!ring) return -ENOMEM; - spin_lock_bh(&ioat->ring_lock); + spin_lock_bh(&chan->cleanup_lock); + spin_lock_bh(&ioat->prep_lock); ioat->ring = ring; ioat->head = 0; ioat->issued = 0; ioat->tail = 0; ioat->alloc_order = order; - spin_unlock_bh(&ioat->ring_lock); + spin_unlock_bh(&ioat->prep_lock); + spin_unlock_bh(&chan->cleanup_lock); tasklet_enable(&chan->cleanup_task); ioat2_start_null_desc(ioat); @@ -653,54 +651,61 @@ bool reshape_ring(struct ioat2_dma_chan *ioat, int order) } /** - * ioat2_alloc_and_lock - common descriptor alloc boilerplate for ioat2,3 ops - * @idx: gets starting descriptor index on successful allocation + * ioat2_check_space_lock - verify space and grab ring producer lock * @ioat: ioat2,3 channel (ring) to operate on * @num_descs: allocation length */ -int ioat2_alloc_and_lock(u16 *idx, struct ioat2_dma_chan *ioat, int num_descs) +int ioat2_check_space_lock(struct ioat2_dma_chan *ioat, int num_descs) { struct ioat_chan_common *chan = &ioat->base; + bool retry; - spin_lock_bh(&ioat->ring_lock); + retry: + spin_lock_bh(&ioat->prep_lock); /* 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", - __func__, num_descs, ioat->head, ioat->tail, - ioat->issued); - spin_unlock_bh(&ioat->ring_lock); - - /* progress reclaim in the allocation failure case we - * may be called under bh_disabled so we need to trigger - * the timer event directly - */ - spin_lock_bh(&chan->cleanup_lock); - if (jiffies > chan->timer.expires && - timer_pending(&chan->timer)) { - struct ioatdma_device *device = chan->device; - - mod_timer(&chan->timer, jiffies + COMPLETION_TIMEOUT); - spin_unlock_bh(&chan->cleanup_lock); - device->timer_fn((unsigned long) &chan->common); - } else - spin_unlock_bh(&chan->cleanup_lock); - return -ENOMEM; + if (likely(ioat2_ring_space(ioat) > num_descs)) { + dev_dbg(to_dev(chan), "%s: num_descs: %d (%x:%x:%x)\n", + __func__, num_descs, ioat->head, ioat->tail, ioat->issued); + ioat->produce = num_descs; + return 0; /* with ioat->prep_lock held */ } + retry = test_and_set_bit(IOAT_RESHAPE_PENDING, &chan->state); + spin_unlock_bh(&ioat->prep_lock); - dev_dbg(to_dev(chan), "%s: num_descs: %d (%x:%x:%x)\n", - __func__, num_descs, ioat->head, ioat->tail, ioat->issued); + /* is another cpu already trying to expand the ring? */ + if (retry) + goto retry; - *idx = ioat2_desc_alloc(ioat, num_descs); - return 0; /* with ioat->ring_lock held */ + spin_lock_bh(&chan->cleanup_lock); + spin_lock_bh(&ioat->prep_lock); + retry = reshape_ring(ioat, ioat->alloc_order + 1); + clear_bit(IOAT_RESHAPE_PENDING, &chan->state); + spin_unlock_bh(&ioat->prep_lock); + spin_unlock_bh(&chan->cleanup_lock); + + /* if we were able to expand the ring retry the allocation */ + if (retry) + goto retry; + + if (printk_ratelimit()) + dev_dbg(to_dev(chan), "%s: ring full! num_descs: %d (%x:%x:%x)\n", + __func__, num_descs, ioat->head, ioat->tail, ioat->issued); + + /* progress reclaim in the allocation failure case we may be + * called under bh_disabled so we need to trigger the timer + * event directly + */ + if (jiffies > chan->timer.expires && timer_pending(&chan->timer)) { + struct ioatdma_device *device = chan->device; + + mod_timer(&chan->timer, jiffies + COMPLETION_TIMEOUT); + device->timer_fn((unsigned long) &chan->common); + } + + return -ENOMEM; } struct dma_async_tx_descriptor * @@ -713,14 +718,11 @@ ioat2_dma_prep_memcpy_lock(struct dma_chan *c, dma_addr_t dma_dest, dma_addr_t dst = dma_dest; dma_addr_t src = dma_src; size_t total_len = len; - int num_descs; - u16 idx; - int i; + int num_descs, idx, i; num_descs = ioat2_xferlen_to_descs(ioat, len); - if (likely(num_descs) && - ioat2_alloc_and_lock(&idx, ioat, num_descs) == 0) - /* pass */; + if (likely(num_descs) && ioat2_check_space_lock(ioat, num_descs) == 0) + idx = ioat->head; else return NULL; i = 0; @@ -777,7 +779,8 @@ void ioat2_free_chan_resources(struct dma_chan *c) device->cleanup_fn((unsigned long) c); device->reset_hw(chan); - spin_lock_bh(&ioat->ring_lock); + spin_lock_bh(&chan->cleanup_lock); + spin_lock_bh(&ioat->prep_lock); descs = ioat2_ring_space(ioat); dev_dbg(to_dev(chan), "freeing %d idle descriptors\n", descs); for (i = 0; i < descs; i++) { @@ -800,7 +803,8 @@ void ioat2_free_chan_resources(struct dma_chan *c) ioat->alloc_order = 0; pci_pool_free(device->completion_pool, chan->completion, chan->completion_dma); - spin_unlock_bh(&ioat->ring_lock); + spin_unlock_bh(&ioat->prep_lock); + spin_unlock_bh(&chan->cleanup_lock); chan->last_completion = 0; chan->completion_dma = 0; -- cgit v1.2.3