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ioat2,3: cacheline align software descriptor allocations 

All the necessary fields for handling an ioat2,3 ring entry can fit into
one cacheline.  Move ->len prior to ->txd in struct ioat_ring_ent, and
move allocation of these entries to a hw-cache-aligned kmem cache to
reduce the number of cachelines dirtied for descriptor management.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2009-09-08 17:53:04 -07:00
parent 0803172778
commit 162b96e63e
3 changed files with 20 additions and 4 deletions
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5
drivers/dma/ioat/dma_v2.c
View File

@ -399,11 +399,12 @@ static struct ioat_ring_ent *ioat2_alloc_ring_ent(struct dma_chan *chan, gfp_t f
return NULL;
memset(hw, 0, sizeof(*hw));
desc = kzalloc(sizeof(*desc), flags);
desc = kmem_cache_alloc(ioat2_cache, flags);
if (!desc) {
pci_pool_free(dma->dma_pool, hw, phys);
return NULL;
}
memset(desc, 0, sizeof(*desc));
dma_async_tx_descriptor_init(&desc->txd, chan);
desc->txd.tx_submit = ioat2_tx_submit_unlock;
@ -418,7 +419,7 @@ static void ioat2_free_ring_ent(struct ioat_ring_ent *desc, struct dma_chan *cha
dma = to_ioatdma_device(chan->device);
pci_pool_free(dma->dma_pool, desc->hw, desc->txd.phys);
kfree(desc);
kmem_cache_free(ioat2_cache, desc);
}
static struct ioat_ring_ent **ioat2_alloc_ring(struct dma_chan *c, int order, gfp_t flags)

3
drivers/dma/ioat/dma_v2.h
View File

@ -116,8 +116,8 @@ static inline u16 ioat2_xferlen_to_descs(struct ioat2_dma_chan *ioat, size_t len
struct ioat_ring_ent {
struct ioat_dma_descriptor *hw;
struct dma_async_tx_descriptor txd;
size_t len;
struct dma_async_tx_descriptor txd;
#ifdef DEBUG
int id;
#endif
@ -143,4 +143,5 @@ int __devinit ioat2_dma_probe(struct ioatdma_device *dev, int dca);
int __devinit ioat3_dma_probe(struct ioatdma_device *dev, int dca);
struct dca_provider * __devinit ioat2_dca_init(struct pci_dev *pdev, void __iomem *iobase);
struct dca_provider * __devinit ioat3_dca_init(struct pci_dev *pdev, void __iomem *iobase);
extern struct kmem_cache *ioat2_cache;
#endif /* IOATDMA_V2_H */

16
drivers/dma/ioat/pci.c
View File

@ -69,6 +69,8 @@ static int ioat_dca_enabled = 1;
module_param(ioat_dca_enabled, int, 0644);
MODULE_PARM_DESC(ioat_dca_enabled, "control support of dca service (default: 1)");
struct kmem_cache *ioat2_cache;
#define DRV_NAME "ioatdma"
static struct pci_driver ioat_pci_driver = {
@ -168,12 +170,24 @@ static void __devexit ioat_remove(struct pci_dev *pdev)
static int __init ioat_init_module(void)
{
return pci_register_driver(&ioat_pci_driver);
int err;
ioat2_cache = kmem_cache_create("ioat2", sizeof(struct ioat_ring_ent),
0, SLAB_HWCACHE_ALIGN, NULL);
if (!ioat2_cache)
return -ENOMEM;
err = pci_register_driver(&ioat_pci_driver);
if (err)
kmem_cache_destroy(ioat2_cache);
return err;
}
module_init(ioat_init_module);
static void __exit ioat_exit_module(void)
{
pci_unregister_driver(&ioat_pci_driver);
kmem_cache_destroy(ioat2_cache);
}
module_exit(ioat_exit_module);