diff options
| author | Anton Blanchard <anton@samba.org> | 2012-06-03 19:43:02 +0000 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2012-07-03 14:14:47 +1000 |
| commit | 0e4bc95d87394364f408627067238453830bdbf3 (patch) | |
| tree | b5dbbb86a43e9fb0db8a865b770da5fad07c89c3 /arch/powerpc/kernel | |
| parent | c1703e85a7b20ffcefd5360e2542460737ecc15c (diff) | |
| download | op-kernel-dev-0e4bc95d87394364f408627067238453830bdbf3.zip op-kernel-dev-0e4bc95d87394364f408627067238453830bdbf3.tar.gz | |
powerpc/iommu: Reduce spinlock coverage in iommu_alloc and iommu_free
We currently hold the IOMMU spinlock around tce_build and tce_flush.
This causes our spinlock hold times to be much higher than required
and can impact multiqueue adapters.
This patch moves tce_build and tce_flush outside of the lock in
iommu_alloc, and tce_flush outside of the lock in iommu_free.
Some performance numbers were obtained with a Chelsio T3 adapter on
two POWER7 boxes, running a 100 session TCP round robin test.
Performance improved 32% with this patch applied.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel')
| -rw-r--r-- | arch/powerpc/kernel/iommu.c | 15 |
1 files changed, 5 insertions, 10 deletions
diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c index 359f078..9c8967f 100644 --- a/arch/powerpc/kernel/iommu.c +++ b/arch/powerpc/kernel/iommu.c @@ -170,13 +170,11 @@ static dma_addr_t iommu_alloc(struct device *dev, struct iommu_table *tbl, int build_fail; spin_lock_irqsave(&(tbl->it_lock), flags); - entry = iommu_range_alloc(dev, tbl, npages, NULL, mask, align_order); + spin_unlock_irqrestore(&(tbl->it_lock), flags); - if (unlikely(entry == DMA_ERROR_CODE)) { - spin_unlock_irqrestore(&(tbl->it_lock), flags); + if (unlikely(entry == DMA_ERROR_CODE)) return DMA_ERROR_CODE; - } entry += tbl->it_offset; /* Offset into real TCE table */ ret = entry << IOMMU_PAGE_SHIFT; /* Set the return dma address */ @@ -192,9 +190,10 @@ static dma_addr_t iommu_alloc(struct device *dev, struct iommu_table *tbl, * not altered. */ if (unlikely(build_fail)) { + spin_lock_irqsave(&(tbl->it_lock), flags); __iommu_free(tbl, ret, npages); - spin_unlock_irqrestore(&(tbl->it_lock), flags); + return DMA_ERROR_CODE; } @@ -202,8 +201,6 @@ static dma_addr_t iommu_alloc(struct device *dev, struct iommu_table *tbl, if (ppc_md.tce_flush) ppc_md.tce_flush(tbl); - spin_unlock_irqrestore(&(tbl->it_lock), flags); - /* Make sure updates are seen by hardware */ mb(); @@ -244,8 +241,8 @@ static void iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr, unsigned long flags; spin_lock_irqsave(&(tbl->it_lock), flags); - __iommu_free(tbl, dma_addr, npages); + spin_unlock_irqrestore(&(tbl->it_lock), flags); /* Make sure TLB cache is flushed if the HW needs it. We do * not do an mb() here on purpose, it is not needed on any of @@ -253,8 +250,6 @@ static void iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr, */ if (ppc_md.tce_flush) ppc_md.tce_flush(tbl); - - spin_unlock_irqrestore(&(tbl->it_lock), flags); } int iommu_map_sg(struct device *dev, struct iommu_table *tbl, |
