From: Eric Dumazet <edumazet@google.com>
Date: Wed, 30 Oct 2019 18:48:44 +0000 (-0700)
Subject: dma-debug: increase HASH_SIZE
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=5e76f564572b85735de4b75a5e73b514be2562be;p=linux.git

dma-debug: increase HASH_SIZE

With modern NIC, it is not unusual having about ~256,000 active dma
mappings and a hash size of 1024 buckets is too small.

Forcing full cache line per bucket does not seem useful, especially now
that we have contention on free_entries_lock for allocations and freeing
of entries.  Better use the space to fit more buckets.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---

diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
index a5b85dabfb8cc..004496654aaa5 100644
--- a/kernel/dma/debug.c
+++ b/kernel/dma/debug.c
@@ -27,7 +27,7 @@
 
 #include <asm/sections.h>
 
-#define HASH_SIZE       1024ULL
+#define HASH_SIZE       16384ULL
 #define HASH_FN_SHIFT   13
 #define HASH_FN_MASK    (HASH_SIZE - 1)
 
@@ -87,7 +87,7 @@ typedef bool (*match_fn)(struct dma_debug_entry *, struct dma_debug_entry *);
 struct hash_bucket {
 	struct list_head list;
 	spinlock_t lock;
-} ____cacheline_aligned_in_smp;
+};
 
 /* Hash list to save the allocated dma addresses */
 static struct hash_bucket dma_entry_hash[HASH_SIZE];