From: Arthur Fabre <afabre@xxxxxxxxxxxxxx>
When copying trait values to or from the caller, the size isn't a
constant so memcpy() ends up being a function call.
Replace it with an inline implementation that only handles the sizes we
support.
We store values "packed", so they won't necessarily be 4 or 8 byte
aligned.
Setting and getting traits is roughly ~40% faster.
Signed-off-by: Arthur Fabre <afabre@xxxxxxxxxxxxxx>
---
include/net/trait.h | 25 +++++++++++++++++++------
1 file changed, 19 insertions(+), 6 deletions(-)
diff --git a/include/net/trait.h b/include/net/trait.h
index 536b8a17dbbc091b4d1a4d7b4b21c1e36adea86a..d4581a877bd57a32e2ad032147c906764d6d37f8 100644
--- a/include/net/trait.h
+++ b/include/net/trait.h
@@ -7,6 +7,7 @@
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/bitops.h>
+#include <linux/unaligned.h>
/* Traits are a very limited KV store, with:
* - 64 keys (0-63).
@@ -145,23 +146,23 @@ int trait_set(void *traits, void *hard_end, u64 key, const void *val, u64 len, u
memmove(traits + off + len, traits + off, traits_size(traits) - off);
}
- /* Set our value. */
- memcpy(traits + off, val, len);
-
- /* Store our length in header. */
u64 encode_len = 0;
-
switch (len) {
case 2:
+ /* Values are least two bytes, so they'll be two byte aligned */
+ *(u16 *)(traits + off) = *(u16 *)val;
encode_len = 1;
break;
case 4:
+ put_unaligned(*(u32 *)val, (u32 *)(traits + off));
encode_len = 2;
break;
case 8:
+ put_unaligned(*(u64 *)val, (u64 *)(traits + off));
encode_len = 3;
break;
}
+
h->high |= (encode_len >> 1) << key;
h->low |= (encode_len & 1) << key;
return 0;
@@ -201,7 +202,19 @@ int trait_get(void *traits, u64 key, void *val, u64 val_len)
if (real_len > val_len)
return -ENOSPC;
- memcpy(val, traits + off, real_len);
+ switch (real_len) {
+ case 2:
+ /* Values are least two bytes, so they'll be two byte aligned */
+ *(u16 *)val = *(u16 *)(traits + off);
+ break;
+ case 4:
+ *(u32 *)val = get_unaligned((u32 *)(traits + off));
+ break;
+ case 8:
+ *(u64 *)val = get_unaligned((u64 *)(traits + off));
+ break;
+ }
+
return real_len;
}
--
2.43.0
