path: root/drivers/dma
diff options
authorDan Williams <dan.j.williams@intel.com>2010-10-13 15:43:10 -0700
committerDan Williams <dan.j.williams@intel.com>2010-10-13 15:43:10 -0700
commitc50a898fd4e736623ee175920db056194e0bb483 (patch)
tree271750360d57da1d982686d8435b8eb3bf3086e4 /drivers/dma
parentcc60f8878eab892c03d06b10f389232b9b66bd83 (diff)
ioat2: fix performance regression
Commit 0793448 "DMAENGINE: generic channel status v2" changed the interface for how dma channel progress is retrieved. It inadvertently exported an internal helper function ioat_tx_status() instead of ioat_dma_tx_status(). The latter polls the hardware to get the latest completion state, while the helper just evaluates the current state without touching hardware. The effect is that we end up waiting for completion timeouts or descriptor allocation errors before the completion state is updated. iperf (before fix): [SUM] 0.0-41.3 sec 364 MBytes 73.9 Mbits/sec iperf (after fix): [SUM] 0.0- 4.5 sec 499 MBytes 940 Mbits/sec This is a regression starting with 2.6.35. Cc: <stable@kernel.org> Cc: Dave Jiang <dave.jiang@intel.com> Cc: Jesse Brandeburg <jesse.brandeburg@intel.com> Cc: Linus Walleij <linus.walleij@stericsson.com> Cc: Maciej Sosnowski <maciej.sosnowski@intel.com> Reported-by: Richard Scobie <richard@sauce.co.nz> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/dma')
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/dma/ioat/dma_v2.c b/drivers/dma/ioat/dma_v2.c
index 216f9d383b5..effd140fc04 100644
--- a/drivers/dma/ioat/dma_v2.c
+++ b/drivers/dma/ioat/dma_v2.c
@@ -879,7 +879,7 @@ int __devinit ioat2_dma_probe(struct ioatdma_device *device, int dca)
dma->device_issue_pending = ioat2_issue_pending;
dma->device_alloc_chan_resources = ioat2_alloc_chan_resources;
dma->device_free_chan_resources = ioat2_free_chan_resources;
- dma->device_tx_status = ioat_tx_status;
+ dma->device_tx_status = ioat_dma_tx_status;
err = ioat_probe(device);
if (err)