PCI: pci-iommu-iotlb-flushing-speedup
The following patch is an update to use an array instead of a list of
IOVA's in the implementation of defered iotlb flushes. It takes
inspiration from sba_iommu.c
I like this implementation better as it encapsulates the batch process
within intel-iommu.c, and no longer touches iova.h (which is shared)
Performance data: Netperf 32byte UDP streaming
2.6.25-rc3-mm1:
IOMMU-strict : 58Mps @ 62% cpu
NO-IOMMU : 71Mbs @ 41% cpu
List-based IOMMU-default-batched-IOTLB flush: 66Mbps @ 57% cpu
with this patch:
IOMMU-strict : 73Mps @ 75% cpu
NO-IOMMU : 74Mbs @ 42% cpu
Array-based IOMMU-default-batched-IOTLB flush: 72Mbps @ 62% cpu
Signed-off-by: <mgross@linux.intel.com>
Cc: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index 8690a0d..301c68f 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -59,8 +59,17 @@
DEFINE_TIMER(unmap_timer, flush_unmaps_timeout, 0, 0);
static struct intel_iommu *g_iommus;
+
+#define HIGH_WATER_MARK 250
+struct deferred_flush_tables {
+ int next;
+ struct iova *iova[HIGH_WATER_MARK];
+ struct dmar_domain *domain[HIGH_WATER_MARK];
+};
+
+static struct deferred_flush_tables *deferred_flush;
+
/* bitmap for indexing intel_iommus */
-static unsigned long *g_iommus_to_flush;
static int g_num_of_iommus;
static DEFINE_SPINLOCK(async_umap_flush_lock);
@@ -68,10 +77,6 @@
static int timer_on;
static long list_size;
-static int high_watermark;
-
-static struct dentry *intel_iommu_debug, *debug;
-
static void domain_remove_dev_info(struct dmar_domain *domain);
@@ -1692,7 +1697,7 @@
struct dmar_rmrr_unit *rmrr;
struct pci_dev *pdev;
struct intel_iommu *iommu;
- int nlongs, i, ret, unit = 0;
+ int i, ret, unit = 0;
/*
* for each drhd
@@ -1711,17 +1716,16 @@
*/
}
- nlongs = BITS_TO_LONGS(g_num_of_iommus);
- g_iommus_to_flush = kzalloc(nlongs * sizeof(unsigned long), GFP_KERNEL);
- if (!g_iommus_to_flush) {
- printk(KERN_ERR "Intel-IOMMU: "
- "Allocating bitmap array failed\n");
- return -ENOMEM;
- }
-
g_iommus = kzalloc(g_num_of_iommus * sizeof(*iommu), GFP_KERNEL);
if (!g_iommus) {
- kfree(g_iommus_to_flush);
+ ret = -ENOMEM;
+ goto error;
+ }
+
+ deferred_flush = kzalloc(g_num_of_iommus *
+ sizeof(struct deferred_flush_tables), GFP_KERNEL);
+ if (!deferred_flush) {
+ kfree(g_iommus);
ret = -ENOMEM;
goto error;
}
@@ -1970,42 +1974,48 @@
static void flush_unmaps(void)
{
- struct iova *node, *n;
- unsigned long flags;
- int i;
+ int i, j;
- spin_lock_irqsave(&async_umap_flush_lock, flags);
timer_on = 0;
/* just flush them all */
for (i = 0; i < g_num_of_iommus; i++) {
- if (test_and_clear_bit(i, g_iommus_to_flush))
+ if (deferred_flush[i].next) {
iommu_flush_iotlb_global(&g_iommus[i], 0);
+ for (j = 0; j < deferred_flush[i].next; j++) {
+ __free_iova(&deferred_flush[i].domain[j]->iovad,
+ deferred_flush[i].iova[j]);
+ }
+ deferred_flush[i].next = 0;
+ }
}
- list_for_each_entry_safe(node, n, &unmaps_to_do, list) {
- /* free iova */
- list_del(&node->list);
- __free_iova(&((struct dmar_domain *)node->dmar)->iovad, node);
-
- }
list_size = 0;
- spin_unlock_irqrestore(&async_umap_flush_lock, flags);
}
static void flush_unmaps_timeout(unsigned long data)
{
+ unsigned long flags;
+
+ spin_lock_irqsave(&async_umap_flush_lock, flags);
flush_unmaps();
+ spin_unlock_irqrestore(&async_umap_flush_lock, flags);
}
static void add_unmap(struct dmar_domain *dom, struct iova *iova)
{
unsigned long flags;
+ int next, iommu_id;
spin_lock_irqsave(&async_umap_flush_lock, flags);
- iova->dmar = dom;
- list_add(&iova->list, &unmaps_to_do);
- set_bit((dom->iommu - g_iommus), g_iommus_to_flush);
+ if (list_size == HIGH_WATER_MARK)
+ flush_unmaps();
+
+ iommu_id = dom->iommu - g_iommus;
+ next = deferred_flush[iommu_id].next;
+ deferred_flush[iommu_id].domain[next] = dom;
+ deferred_flush[iommu_id].iova[next] = iova;
+ deferred_flush[iommu_id].next++;
if (!timer_on) {
mod_timer(&unmap_timer, jiffies + msecs_to_jiffies(10));
@@ -2054,8 +2064,6 @@
* queue up the release of the unmap to save the 1/6th of the
* cpu used up by the iotlb flush operation...
*/
- if (list_size > high_watermark)
- flush_unmaps();
}
}
@@ -2380,10 +2388,6 @@
if (dmar_table_init())
return -ENODEV;
- high_watermark = 250;
- intel_iommu_debug = debugfs_create_dir("intel_iommu", NULL);
- debug = debugfs_create_u32("high_watermark", S_IWUGO | S_IRUGO,
- intel_iommu_debug, &high_watermark);
iommu_init_mempool();
dmar_init_reserved_ranges();