padata: make the sequence counter an atomic_t
Using a spinlock to atomically increase a counter sounds wrong -- we've
atomic_t for this!
Also move 'seq_nr' to a different cache line than 'lock' to reduce cache
line trashing. This has the nice side effect of decreasing the size of
struct parallel_data from 192 to 128 bytes for a x86-64 build, e.g.
occupying only two instead of three cache lines.
Those changes results in a 5% performance increase on an IPsec test run
using pcrypt.
Btw. the seq_lock spinlock was never explicitly initialized -- one more
reason to get rid of it.
Signed-off-by: Mathias Krause <mathias.krause@secunet.com>
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/include/linux/padata.h b/include/linux/padata.h
index 86292be..4386946 100644
--- a/include/linux/padata.h
+++ b/include/linux/padata.h
@@ -129,10 +129,9 @@
struct padata_serial_queue __percpu *squeue;
atomic_t reorder_objects;
atomic_t refcnt;
+ atomic_t seq_nr;
struct padata_cpumask cpumask;
spinlock_t lock ____cacheline_aligned;
- spinlock_t seq_lock;
- unsigned int seq_nr;
unsigned int processed;
struct timer_list timer;
};