From: Anton Blanchard <anton@samba.org>
To: benh@kernel.crashing.org, paulus@samba.org, olof@lixom.net,
michael@ellerman.id.au
Cc: linuxppc-dev@lists.ozlabs.org
Subject: [PATCH 3/5] powerpc: iommu: Reduce spinlock coverage in iommu_free
Date: Mon, 4 Jun 2012 15:43:44 +1000 [thread overview]
Message-ID: <20120604154344.4cadd299@kryten> (raw)
In-Reply-To: <20120604154213.173feecb@kryten>
This patch moves tce_free 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 25% with this patch applied.
Signed-off-by: Anton Blanchard <anton@samba.org>
---
Index: linux-build/arch/powerpc/kernel/iommu.c
===================================================================
--- linux-build.orig/arch/powerpc/kernel/iommu.c 2012-06-04 10:38:41.461284266 +1000
+++ linux-build/arch/powerpc/kernel/iommu.c 2012-06-04 10:38:43.813334034 +1000
@@ -190,10 +190,7 @@ static dma_addr_t iommu_alloc(struct dev
* 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;
}
@@ -207,8 +204,8 @@ static dma_addr_t iommu_alloc(struct dev
return ret;
}
-static void __iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,
- unsigned int npages)
+static bool iommu_free_check(struct iommu_table *tbl, dma_addr_t dma_addr,
+ unsigned int npages)
{
unsigned long entry, free_entry;
@@ -228,21 +225,53 @@ static void __iommu_free(struct iommu_ta
printk(KERN_INFO "\tindex = 0x%llx\n", (u64)tbl->it_index);
WARN_ON(1);
}
- return;
+
+ return false;
}
+ return true;
+}
+
+static void __iommu_free_locked(struct iommu_table *tbl, dma_addr_t dma_addr,
+ unsigned int npages)
+{
+ unsigned long entry, free_entry;
+
+ BUG_ON(!spin_is_locked(&tbl->it_lock));
+
+ entry = dma_addr >> IOMMU_PAGE_SHIFT;
+ free_entry = entry - tbl->it_offset;
+
+ if (!iommu_free_check(tbl, dma_addr, npages))
+ return;
+
ppc_md.tce_free(tbl, entry, npages);
bitmap_clear(tbl->it_map, free_entry, npages);
}
-static void iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,
- unsigned int npages)
+static void __iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,
+ unsigned int npages)
{
+ unsigned long entry, free_entry;
unsigned long flags;
+ entry = dma_addr >> IOMMU_PAGE_SHIFT;
+ free_entry = entry - tbl->it_offset;
+
+ if (!iommu_free_check(tbl, dma_addr, npages))
+ return;
+
+ ppc_md.tce_free(tbl, entry, npages);
+
spin_lock_irqsave(&(tbl->it_lock), flags);
- __iommu_free(tbl, dma_addr, npages);
+ bitmap_clear(tbl->it_map, free_entry, npages);
spin_unlock_irqrestore(&(tbl->it_lock), flags);
+}
+
+static void iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,
+ unsigned int npages)
+{
+ __iommu_free(tbl, dma_addr, npages);
/* 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
@@ -390,7 +419,7 @@ int iommu_map_sg(struct device *dev, str
vaddr = s->dma_address & IOMMU_PAGE_MASK;
npages = iommu_num_pages(s->dma_address, s->dma_length,
IOMMU_PAGE_SIZE);
- __iommu_free(tbl, vaddr, npages);
+ __iommu_free_locked(tbl, vaddr, npages);
s->dma_address = DMA_ERROR_CODE;
s->dma_length = 0;
}
@@ -425,7 +454,7 @@ void iommu_unmap_sg(struct iommu_table *
break;
npages = iommu_num_pages(dma_handle, sg->dma_length,
IOMMU_PAGE_SIZE);
- __iommu_free(tbl, dma_handle, npages);
+ __iommu_free_locked(tbl, dma_handle, npages);
sg = sg_next(sg);
}
next prev parent reply other threads:[~2012-06-04 5:43 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-04 5:42 [PATCH 1/5] powerpc/pseries: Disable interrupts around IOMMU percpu data accesses Anton Blanchard
2012-06-04 5:43 ` [PATCH 2/5] powerpc: iommu: Reduce spinlock coverage in iommu_alloc and iommu_free Anton Blanchard
2012-06-04 5:43 ` Anton Blanchard [this message]
2012-06-04 5:44 ` [PATCH 4/5] powerpc: iommu: Push spinlock into iommu_range_alloc and __iommu_free Anton Blanchard
2012-06-04 5:45 ` [PATCH 5/5] powerpc: iommu: Implement IOMMU pools to improve multiqueue adapter performance Anton Blanchard
2012-06-08 2:43 ` Michael Ellerman
2012-06-08 4:02 ` Anton Blanchard
2012-06-08 4:03 ` Michael Ellerman
2012-06-08 4:14 ` Anton Blanchard
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