bb620c3d39
In iperf experiments running linux as the Tx side (TCP client) with 10 threads results in a severe performance drop when TSO is disabled, indicating a weakness in the software that can be avoided by using the scalable IOMMU arena DMA allocation. Baseline numbers before this patch: with default settings (TSO enabled) : 9-9.5 Gbps Disable TSO using ethtool- drops badly: 2-3 Gbps. After this patch, iperf client with 10 threads, can give a throughput of at least 8.5 Gbps, even when TSO is disabled. Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: David S. Miller <davem@davemloft.net>
51 lines
1.3 KiB
C
51 lines
1.3 KiB
C
/* iommu_common.h: UltraSparc SBUS/PCI common iommu declarations.
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*
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* Copyright (C) 1999, 2008 David S. Miller (davem@davemloft.net)
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*/
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#ifndef _IOMMU_COMMON_H
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#define _IOMMU_COMMON_H
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <linux/scatterlist.h>
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#include <linux/device.h>
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#include <linux/iommu-helper.h>
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#include <asm/iommu.h>
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#include <asm/scatterlist.h>
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/*
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* These give mapping size of each iommu pte/tlb.
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*/
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#define IO_PAGE_SHIFT 13
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#define IO_PAGE_SIZE (1UL << IO_PAGE_SHIFT)
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#define IO_PAGE_MASK (~(IO_PAGE_SIZE-1))
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#define IO_PAGE_ALIGN(addr) ALIGN(addr, IO_PAGE_SIZE)
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#define IO_TSB_ENTRIES (128*1024)
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#define IO_TSB_SIZE (IO_TSB_ENTRIES * 8)
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/*
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* This is the hardwired shift in the iotlb tag/data parts.
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*/
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#define IOMMU_PAGE_SHIFT 13
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#define SG_ENT_PHYS_ADDRESS(SG) (__pa(sg_virt((SG))))
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static inline int is_span_boundary(unsigned long entry,
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unsigned long shift,
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unsigned long boundary_size,
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struct scatterlist *outs,
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struct scatterlist *sg)
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{
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unsigned long paddr = SG_ENT_PHYS_ADDRESS(outs);
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int nr = iommu_num_pages(paddr, outs->dma_length + sg->length,
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IO_PAGE_SIZE);
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return iommu_is_span_boundary(entry, nr, shift, boundary_size);
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}
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#endif /* _IOMMU_COMMON_H */
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