[sheepdog] [PATCH v2 1/4] lib, sheep: exclude stuff for tracing when it is not enabled

[Liu Yuan]

On Tue, Dec 17, 2013 at 11:42:53PM +0900, Hitoshi Mitake wrote:
> From: Hitoshi Mitake <mitake.hitoshi at lab.ntt.co.jp>
> 
> The current build process of sheepdog compiles stuff for tracing even
> if tracing is disabled. Basically they are not harmful but causes
> memory consumption (tid_map), we should exlucde them when tracing is
> disabled.
> 
> In addition, this patch adds a new mutex tid_map_lock for protecting
> tid_map. Previous work.c used wi->pending_lock also for protecting the
> bitmap. This protection scheme is very confusing.
> 
> Signed-off-by: Hitoshi Mitake <mitake.hitoshi at lab.ntt.co.jp>
> ---
>  include/work.h      |  7 +++++--
>  lib/Makefile.am     |  4 ++++
>  lib/work.c          | 58 ++++++++++++++++++++++++++++++++++++++++-------------
>  sheep/Makefile.am   |  1 +
>  sheep/trace/trace.c |  1 +
>  5 files changed, 55 insertions(+), 16 deletions(-)
> 
> diff --git a/include/work.h b/include/work.h
> index a5808b5..0cb3313 100644
> --- a/include/work.h
> +++ b/include/work.h
> @@ -61,9 +61,12 @@ static inline bool is_worker_thread(void)
>  int init_work_queue(size_t (*get_nr_nodes)(void));
>  struct work_queue *create_work_queue(const char *name, enum wq_thread_control);
>  struct work_queue *create_ordered_work_queue(const char *name);
> -void suspend_worker_threads(void);
> -void resume_worker_threads(void);
>  void queue_work(struct work_queue *q, struct work *work);
>  bool work_queue_empty(struct work_queue *q);
>  
> +#ifdef ENABLE_TRACE
> +void suspend_worker_threads(void);
> +void resume_worker_threads(void);
> +#endif	/* BUILD_TRACE */
> +
>  #endif
> diff --git a/lib/Makefile.am b/lib/Makefile.am
> index a681167..5204879 100644
> --- a/lib/Makefile.am
> +++ b/lib/Makefile.am
> @@ -11,6 +11,10 @@ if BUILD_SHA1_HW
>  libsheepdog_a_SOURCES	+= sha1_ssse3.S
>  endif
>  
> +if BUILD_TRACE
> +AM_CPPFLAGS		+= -DENABLE_TRACE
> +endif
> +
>  # support for GNU Flymake
>  check-syntax:
>  	$(COMPILE) -fsyntax-only $(CHK_SOURCES)
> diff --git a/lib/work.c b/lib/work.c
> index 6933e1a..84eb727 100644
> --- a/lib/work.c
> +++ b/lib/work.c
> @@ -33,13 +33,19 @@
>  #include "work.h"
>  #include "event.h"
>  
> +#ifdef ENABLE_TRACE
> +
>  #define TID_MAX_DEFAULT 0x8000 /* default maximum tid for most systems */
>  
>  static size_t tid_max;
>  static unsigned long *tid_map;
> +static pthread_mutex_t tid_map_lock = PTHREAD_MUTEX_INITIALIZER;
> +
>  static int resume_efd;
>  static int ack_efd;
>  
> +#endif	/* ENABLE_TRACE */
> +
>  /*
>   * The protection period from shrinking work queue.  This is necessary
>   * to avoid many calls of pthread_create.  Without it, threads are
> @@ -155,6 +161,8 @@ static int create_worker_threads(struct worker_info *wi, size_t nr_threads)
>  	return 0;
>  }
>  
> +#ifdef ENABLE_TRACE
> +
>  void suspend_worker_threads(void)
>  {
>  	struct worker_info *wi;
> @@ -197,6 +205,18 @@ void resume_worker_threads(void)
>  	}
>  }
>  
> +static void suspend(int num)
> +{
> +	int uninitialized_var(value);
> +
> +	eventfd_xwrite(ack_efd, 1); /* ack of suspend */
> +	value = eventfd_xread(resume_efd);
> +	assert(value == 1);
> +	eventfd_xwrite(ack_efd, 1); /* ack of resume */
> +}
> +
> +#endif	/* ENABLE_TRACE */
> +
>  void queue_work(struct work_queue *q, struct work *work)
>  {
>  	struct worker_info *wi = container_of(q, struct worker_info, q);
> @@ -252,7 +272,9 @@ static void *worker_routine(void *arg)
>  	/* started this thread */
>  	pthread_mutex_unlock(&wi->startup_lock);
>  
> -	pthread_mutex_lock(&wi->pending_lock);
> +#ifdef ENABLE_TRACE
> +
> +	pthread_mutex_lock(&tid_map_lock);
>  	if (tid > tid_max) {
>  		size_t old_tid_max = tid_max;
>  
> @@ -263,14 +285,22 @@ static void *worker_routine(void *arg)
>  		tid_map = alloc_bitmap(tid_map, old_tid_max, tid_max);
>  	}
>  	set_bit(tid, tid_map);
> -	pthread_mutex_unlock(&wi->pending_lock);
> +	pthread_mutex_unlock(&tid_map_lock);
> +
> +#endif	/* ENABLE_TRACE */

How about grouping these lines into a function? This really messes up the code
and hard to maintain.

Then 

#ifdef ENABLE_TRACE
functions() { do something }
#else
functions() { do nothing }
#endif

Thanks
Yuan