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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>
This commit is contained in:
mark gross 2008-04-18 13:53:58 -07:00 committed by Greg Kroah-Hartman
parent a391f19717
commit 80b20dd853
2 changed files with 40 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

76
drivers/pci/intel-iommu.c
View File

@ -59,8 +59,17 @@ static void flush_unmaps_timeout(unsigned long data);
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 LIST_HEAD(unmaps_to_do);
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 @@ int __init init_dmars(void)
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 @@ int __init init_dmars(void)
*/
}
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 @@ error:
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 @@ static void intel_unmap_single(struct device *dev, dma_addr_t dev_addr,
* 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 @@ int __init intel_iommu_init(void)
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();

2
drivers/pci/iova.h
View File

@ -24,8 +24,6 @@ struct iova {
struct rb_node node;
unsigned long pfn_hi; /* IOMMU dish out addr hi */
unsigned long pfn_lo; /* IOMMU dish out addr lo */
struct list_head list;
void *dmar;
};
/* holds all the iova translations for a domain */