On 30/11/2018 17:54, Qian Cai wrote:
The amount of DMA mappings from Hisilicon HNS ethernet devices is huge,
so it could trigger "DMA-API: debugging out of memory - disabling".
hnae_get_handle [1]
hnae_init_queue
hnae_init_ring
hnae_alloc_buffers [2]
debug_dma_map_page
dma_entry_alloc
[1] for (i = 0; i < handle->q_num; i++)
[2] for (i = 0; i < ring->desc_num; i++)
On this Huawei TaiShan 2280 aarch64 server, it has reached the limit
already,
4 (ports) x 16 (handles) x 1024 (rings) = 65536
Added a Kconfig entry for PREALLOC_DMA_DEBUG_ENTRIES, so make it easier
for users to deal with special cases like this.
Signed-off-by: Qian Cai <c...@gmx.us>
---
kernel/dma/debug.c | 9 ++-------
lib/Kconfig.debug | 9 +++++++++
2 files changed, 11 insertions(+), 7 deletions(-)
Oh, right, the arch overrides actually got cleaned up already. I'd
forgotten that...
diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
index 231ca4628062..3752fb23f72f 100644
--- a/kernel/dma/debug.c
+++ b/kernel/dma/debug.c
@@ -41,11 +41,6 @@
#define HASH_FN_SHIFT 13
#define HASH_FN_MASK (HASH_SIZE - 1)
-/* allow architectures to override this if absolutely required */
-#ifndef PREALLOC_DMA_DEBUG_ENTRIES
-#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
-#endif
-
enum {
dma_debug_single,
dma_debug_page,
@@ -132,7 +127,7 @@ static u32 min_free_entries;
static u32 nr_total_entries;
/* number of preallocated entries requested by kernel cmdline */
-static u32 nr_prealloc_entries = PREALLOC_DMA_DEBUG_ENTRIES;
+static u32 nr_prealloc_entries = CONFIG_PREALLOC_DMA_DEBUG_ENTRIES;
/* debugfs dentry's for the stuff above */
static struct dentry *dma_debug_dent __read_mostly;
@@ -1063,7 +1058,7 @@ static __init int dma_debug_entries_cmdline(char *str)
if (!str)
return -EINVAL;
if (!get_option(&str, &nr_prealloc_entries))
- nr_prealloc_entries = PREALLOC_DMA_DEBUG_ENTRIES;
+ nr_prealloc_entries = CONFIG_PREALLOC_DMA_DEBUG_ENTRIES;
return 0;
}
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 1af29b8224fd..2c281edcb5ad 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1659,6 +1659,15 @@ config DMA_API_DEBUG
If unsure, say N.
+config PREALLOC_DMA_DEBUG_ENTRIES
+ int "Preallocated DMA-API debugging entries"
+ depends on DMA_API_DEBUG
+ default 65536
I was assuming the point was to also add something like
default 131072 if HNS_ENET
so that DMA debug doesn't require too much thought from the user. If
they still have to notice the overflow message and empirically figure
out a value that does work, rebuilding the kernel each time is far less
convenient than simply adding "dma_debug_entries=..." to their kernel
command line and rebooting, which they can do today. If they do already
know up-front that the default will need overriding and what the
appropriate value is, then the command line still seems seems just as
convenient.
Robin.
+ help
+ The number of preallocated entries for DMA-API debugging code. One
+ entry is required per DMA-API allocation. Increase this if the DMA-API
+ debugging code disables itself because the default is too low.
+
config DMA_API_DEBUG_SG
bool "Debug DMA scatter-gather usage"
default y
