linux-kernel - [PATCH 16/23] iommu/amd: Optimize dma_ops_free

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Date:	Tue, 22 Dec 2015 23:21:21 +0100
From:	Joerg Roedel <joro@...tes.org>
To:	iommu@...ts.linux-foundation.org
Cc:	linux-kernel@...r.kernel.org, joro@...tes.org, jroedel@...e.de
Subject: [PATCH 16/23] iommu/amd: Optimize dma_ops_free_addresses

From: Joerg Roedel <jroedel@...e.de>

Don't flush the iommu tlb when we free something behind the
current next_bit pointer. Update the next_bit pointer
instead and let the flush happen on the next wraparound in
the allocation path.

Signed-off-by: Joerg Roedel <jroedel@...e.de>
---
 drivers/iommu/amd_iommu.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 39a2048..c657e48 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1633,8 +1633,7 @@ static void dma_ops_free_addresses(struct dma_ops_domain *dom,
 		return;
 #endif
 
-	if (amd_iommu_unmap_flush ||
-	    (address + pages > range->next_bit)) {
+	if (amd_iommu_unmap_flush) {
 		domain_flush_tlb(&dom->domain);
 		domain_flush_complete(&dom->domain);
 	}
@@ -1642,6 +1641,8 @@ static void dma_ops_free_addresses(struct dma_ops_domain *dom,
 	address = (address % APERTURE_RANGE_SIZE) >> PAGE_SHIFT;
 
 	spin_lock_irqsave(&range->bitmap_lock, flags);
+	if (address + pages > range->next_bit)
+		range->next_bit = address + pages;
 	bitmap_clear(range->bitmap, address, pages);
 	spin_unlock_irqrestore(&range->bitmap_lock, flags);
 
-- 
1.9.1

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