From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Subject: Re: [PATCH RFC 1/6] spinlock: Add library function to allocate spinlock buckets array Date: Mon, 12 Sep 2016 08:17:46 -0700 Message-ID: <1473693466.4320.1.camel@gmail.com> References: <1473463197-3076903-1-git-send-email-tom@herbertland.com> <1473463197-3076903-2-git-send-email-tom@herbertland.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: davem@davemloft.net, netdev@vger.kernel.org, kernel-team@fb.com, tgraf@suug.ch To: Tom Herbert Return-path: Received: from mail-pf0-f194.google.com ([209.85.192.194]:35497 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756086AbcILPRs (ORCPT ); Mon, 12 Sep 2016 11:17:48 -0400 Received: by mail-pf0-f194.google.com with SMTP id i75so3309143pfa.2 for ; Mon, 12 Sep 2016 08:17:48 -0700 (PDT) In-Reply-To: <1473463197-3076903-2-git-send-email-tom@herbertland.com> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, 2016-09-09 at 16:19 -0700, Tom Herbert wrote: > Add two new library functions alloc_bucket_spinlocks and > free_bucket_spinlocks. These are use to allocate and free an array > of spinlocks that are useful as locks for hash buckets. The interface > specifies the maximum number of spinlocks in the array as well > as a CPU multiplier to derive the number of spinlocks to allocate. > The number to allocated is rounded up to a power of two to make > the array amenable to hash lookup. > > Signed-off-by: Tom Herbert I like this idea!! Reviewed by Greg Rose > --- > include/linux/spinlock.h | 6 +++++ > lib/Makefile | 2 +- > lib/bucket_locks.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 70 insertions(+), 1 deletion(-) > create mode 100644 lib/bucket_locks.c > > diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h > index 47dd0ce..4ebdfbf 100644 > --- a/include/linux/spinlock.h > +++ b/include/linux/spinlock.h > @@ -416,4 +416,10 @@ extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock); > #define atomic_dec_and_lock(atomic, lock) \ > __cond_lock(lock, _atomic_dec_and_lock(atomic, lock)) > > +int alloc_bucket_spinlocks(spinlock_t **locks, unsigned int *lock_mask, > + unsigned int max_size, unsigned int cpu_mult, > + gfp_t gfp); > + > +void free_bucket_spinlocks(spinlock_t *locks); > + > #endif /* __LINUX_SPINLOCK_H */ > diff --git a/lib/Makefile b/lib/Makefile > index cfa68eb..a1dedf1 100644 > --- a/lib/Makefile > +++ b/lib/Makefile > @@ -37,7 +37,7 @@ obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \ > gcd.o lcm.o list_sort.o uuid.o flex_array.o iov_iter.o clz_ctz.o \ > bsearch.o find_bit.o llist.o memweight.o kfifo.o \ > percpu-refcount.o percpu_ida.o rhashtable.o reciprocal_div.o \ > - once.o > + once.o bucket_locks.o > obj-y += string_helpers.o > obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o > obj-y += hexdump.o > diff --git a/lib/bucket_locks.c b/lib/bucket_locks.c > new file mode 100644 > index 0000000..bb9bf11 > --- /dev/null > +++ b/lib/bucket_locks.c > @@ -0,0 +1,63 @@ > +#include > +#include > +#include > +#include > +#include > + > +/* Allocate an array of spinlocks to be accessed by a hash. Two arguments > + * indicate the number of elements to allocate in the array. max_size > + * gives the maximum number of elements to allocate. cpu_mult gives > + * the number of locks per CPU to allocate. The size is rounded up > + * to a power of 2 to be suitable as a hash table. > + */ > +int alloc_bucket_spinlocks(spinlock_t **locks, unsigned int *locks_mask, > + unsigned int max_size, unsigned int cpu_mult, > + gfp_t gfp) > +{ > + unsigned int i, size; > +#if defined(CONFIG_PROVE_LOCKING) > + unsigned int nr_pcpus = 2; > +#else > + unsigned int nr_pcpus = num_possible_cpus(); > +#endif > + spinlock_t *tlocks = NULL; > + > + if (cpu_mult) { > + nr_pcpus = min_t(unsigned int, nr_pcpus, 64UL); > + size = min_t(unsigned int, nr_pcpus * cpu_mult, max_size); > + } else { > + size = max_size; > + } > + size = roundup_pow_of_two(size); > + > + if (!size) > + return -EINVAL; > + > + if (sizeof(spinlock_t) != 0) { > +#ifdef CONFIG_NUMA > + if (size * sizeof(spinlock_t) > PAGE_SIZE && > + gfp == GFP_KERNEL) > + tlocks = vmalloc(size * sizeof(spinlock_t)); > +#endif > + if (gfp != GFP_KERNEL) > + gfp |= __GFP_NOWARN | __GFP_NORETRY; > + > + if (!tlocks) > + tlocks = kmalloc_array(size, sizeof(spinlock_t), gfp); > + if (!tlocks) > + return -ENOMEM; > + for (i = 0; i < size; i++) > + spin_lock_init(&tlocks[i]); > + } > + *locks = tlocks; > + *locks_mask = size - 1; > + > + return 0; > +} > +EXPORT_SYMBOL(alloc_bucket_spinlocks); > + > +void free_bucket_spinlocks(spinlock_t *locks) > +{ > + kvfree(locks); > +} > +EXPORT_SYMBOL(free_bucket_spinlocks);