Messages in this thread | | | Subject | Re: [PATCH v2 1/2] swiotlb: add debugfs to track swiotlb buffer usage | From | Joe Jin <> | Date | Mon, 10 Dec 2018 09:10:37 -0800 |
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On 12/9/18 4:37 PM, Dongli Zhang wrote: > The device driver will not be able to do dma operations once swiotlb buffer > is full, either because the driver is using so many IO TLB blocks inflight, > or because there is memory leak issue in device driver. To export the > swiotlb buffer usage via debugfs would help the user estimate the size of > swiotlb buffer to pre-allocate or analyze device driver memory leak issue. > > Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: Joe Jin <joe.jin@oracle.com>
> --- > Changed since v1: > * init debugfs with late_initcall (suggested by Robin Murphy) > * create debugfs entries with debugfs_create_ulong(suggested by Robin Murphy) > > kernel/dma/swiotlb.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 50 insertions(+) > > diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c > index 045930e..3979c2c 100644 > --- a/kernel/dma/swiotlb.c > +++ b/kernel/dma/swiotlb.c > @@ -35,6 +35,9 @@ > #include <linux/scatterlist.h> > #include <linux/mem_encrypt.h> > #include <linux/set_memory.h> > +#ifdef CONFIG_DEBUG_FS > +#include <linux/debugfs.h> > +#endif > > #include <asm/io.h> > #include <asm/dma.h> > @@ -73,6 +76,13 @@ static phys_addr_t io_tlb_start, io_tlb_end; > */ > static unsigned long io_tlb_nslabs; > > +#ifdef CONFIG_DEBUG_FS > +/* > + * The number of used IO TLB block > + */ > +static unsigned long io_tlb_used; > +#endif > + > /* > * This is a free list describing the number of free entries available from > * each index > @@ -528,6 +538,9 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, > dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes)\n", size); > return SWIOTLB_MAP_ERROR; > found: > +#ifdef CONFIG_DEBUG_FS > + io_tlb_used += nslots; > +#endif > spin_unlock_irqrestore(&io_tlb_lock, flags); > > /* > @@ -588,6 +601,10 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr, > */ > for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--) > io_tlb_list[i] = ++count; > + > +#ifdef CONFIG_DEBUG_FS > + io_tlb_used -= nslots; > +#endif > } > spin_unlock_irqrestore(&io_tlb_lock, flags); > } > @@ -883,3 +900,36 @@ const struct dma_map_ops swiotlb_dma_ops = { > .dma_supported = dma_direct_supported, > }; > EXPORT_SYMBOL(swiotlb_dma_ops); > + > +#ifdef CONFIG_DEBUG_FS > + > +static int __init swiotlb_create_debugfs(void) > +{ > + static struct dentry *d_swiotlb_usage; > + struct dentry *ent; > + > + d_swiotlb_usage = debugfs_create_dir("swiotlb", NULL); > + > + if (!d_swiotlb_usage) > + return -ENOMEM; > + > + ent = debugfs_create_ulong("io_tlb_nslabs", 0400, > + d_swiotlb_usage, &io_tlb_nslabs); > + if (!ent) > + goto fail; > + > + ent = debugfs_create_ulong("io_tlb_used", 0400, > + d_swiotlb_usage, &io_tlb_used); > + if (!ent) > + goto fail; > + > + return 0; > + > +fail: > + debugfs_remove_recursive(d_swiotlb_usage); > + return -ENOMEM; > +} > + > +late_initcall(swiotlb_create_debugfs); > + > +#endif >
-- Oracle <http://www.oracle.com> Joe Jin | Software Development Director ORACLE | Linux and Virtualization 500 Oracle Parkway Redwood City, CA US 94065
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