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authorZoltan Kiss <zoltan.kiss@citrix.com>2013-09-05 00:11:05 +0400
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2013-10-02 20:53:26 +0400
commit2b2b614dd24e4e6474fcf2dcf69c95c908838959 (patch)
tree9874899c477d237e1ec207834fc730c1151088f5 /drivers/xen/swiotlb-xen.c
parent04b772d2b819f0dda2163e3193fa7cd447a6245c (diff)
downloadlinux-2b2b614dd24e4e6474fcf2dcf69c95c908838959.tar.xz
tracing/events: Add bounce tracing to swiotbl
Ftrace is currently not able to detect when SWIOTLB has to do double buffering. Under Xen you can only see it indirectly in function_graph, when xen_swiotlb_map_page() doesn't stop after range_straddles_page_boundary(), but calls spinlock functions, memcpy() and xen_phys_to_bus() as well. This patch introduces the swiotlb:swiotlb_bounced event, which also prints out the following informations to help you find out why bouncing happened: dev_name: 0000:08:00.0 dma_mask=ffffffffffffffff dev_addr=9149f000 size=32768 swiotlb_force=0 If you use Xen, and (dev_addr + size + 1) > dma_mask, the buffer is out of the device's DMA range. If swiotlb_force == 1, you should really change the kernel parameters. Otherwise, the buffer is not contiguous in mfn space. Signed-off-by: Zoltan Kiss <zoltan.kiss@citrix.com> [v1: Don't print 'swiotlb_force=X', just print swiotlb_force if it is enabled] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'drivers/xen/swiotlb-xen.c')
-rw-r--r--drivers/xen/swiotlb-xen.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 1b2277c311d2..b31081007a81 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -42,6 +42,9 @@
#include <xen/page.h>
#include <xen/xen-ops.h>
#include <xen/hvc-console.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/swiotlb.h>
/*
* Used to do a quick range check in swiotlb_tbl_unmap_single and
* swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this
@@ -358,6 +361,8 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
/*
* Oh well, have to allocate and map a bounce buffer.
*/
+ trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force);
+
map = swiotlb_tbl_map_single(dev, start_dma_addr, phys, size, dir);
if (map == SWIOTLB_MAP_ERROR)
return DMA_ERROR_CODE;