[PATCH v3] Improve the performance of --num-threads -d 31

Minfei Huang mhuang at redhat.com
Sun Mar 6 23:04:58 PST 2016


Hi, Wenjian.

Since your patch applied Minoru Usui's draft patch, I have vierified it.
And it works well under 4T memory.

applied makedumpfile with option -d 31
real    3m48.681s

applied makedumpfile with option -d 31 --num-threads 32
real    3m3.533s

original makedumpfile with option -d 31
real    3m57.163s

Now with or without option --num-thread, it takes almost same time.

Thanks
Minfei

On 03/04/16 at 04:35pm, Zhou Wenjian wrote:
> v3:
>         1. remove some unused variables
> 	2. fix a bug caused by the wrong logic
> 	3. fix a bug caused by optimising
> 	4. improve more performance by using Minoru Usui's code
> 
> multi-threads implementation will introduce extra cost when handling
> each page. The origin implementation will also do the extra work for
> filtered pages. So there is a big performance degradation in
> --num-threads -d 31.
> The new implementation won't do the extra work for filtered pages any
> more. So the performance of -d 31 is close to that of serial processing.
> 
> The new implementation is just like the following:
>         * The basic idea is producer producing page and consumer writing page.
>         * Each producer have a page_flag_buf list which is used for storing
>           page's description.
>         * The size of page_flag_buf is little so it won't take too much memory.
>         * And all producers will share a page_data_buf array which is
>           used for storing page's compressed data.
>         * The main thread is the consumer. It will find the next pfn and write
>           it into file.
>         * The next pfn is smallest pfn in all page_flag_buf.
> 
> Signed-off-by: Minoru Usui <min-usui at ti.jp.nec.com>
> Signed-off-by: Zhou Wenjian <zhouwj-fnst at cn.fujitsu.com>
> ---
>  makedumpfile.c | 300 +++++++++++++++++++++++++++++++++++----------------------
>  makedumpfile.h |  33 ++++---
>  2 files changed, 203 insertions(+), 130 deletions(-)
> 
> diff --git a/makedumpfile.c b/makedumpfile.c
> index fa0b779..d75f7f7 100644
> --- a/makedumpfile.c
> +++ b/makedumpfile.c
> @@ -3483,7 +3483,8 @@ initial_for_parallel()
>  	unsigned long page_data_buf_size;
>  	unsigned long limit_size;
>  	int page_data_num;
> -	int i;
> +	struct page_flag *current;
> +	int i, j;
>  
>  	len_buf_out = calculate_len_buf_out(info->page_size);
>  
> @@ -3560,10 +3561,16 @@ initial_for_parallel()
>  
>  	limit_size = (get_free_memory_size()
>  		      - MAP_REGION * info->num_threads) * 0.6;
> +	if (limit_size < 0) {
> +		MSG("Free memory is not enough for multi-threads\n");
> +		return FALSE;
> +	}
>  
>  	page_data_num = limit_size / page_data_buf_size;
> +	info->num_buffers = 3 * info->num_threads;
>  
> -	info->num_buffers = MIN(NUM_BUFFERS, page_data_num);
> +	info->num_buffers = MAX(info->num_buffers, NUM_BUFFERS);
> +	info->num_buffers = MIN(info->num_buffers, page_data_num);
>  
>  	DEBUG_MSG("Number of struct page_data for produce/consume: %d\n",
>  			info->num_buffers);
> @@ -3588,6 +3595,36 @@ initial_for_parallel()
>  	}
>  
>  	/*
> +	 * initial page_flag for each thread
> +	 */
> +	if ((info->page_flag_buf = malloc(sizeof(void *) * info->num_threads))
> +	    == NULL) {
> +		MSG("Can't allocate memory for page_flag_buf. %s\n",
> +				strerror(errno));
> +		return FALSE;
> +	}
> +	memset(info->page_flag_buf, 0, sizeof(void *) * info->num_threads);
> +
> +	for (i = 0; i < info->num_threads; i++) {
> +		if ((info->page_flag_buf[i] = calloc(1, sizeof(struct page_flag))) == NULL) {
> +			MSG("Can't allocate memory for page_flag. %s\n",
> +				strerror(errno));
> +			return FALSE;
> +		}
> +		current = info->page_flag_buf[i];
> +
> +		for (j = 1; j < NUM_BUFFERS; j++) {
> +			if ((current->next = calloc(1, sizeof(struct page_flag))) == NULL) {
> +				MSG("Can't allocate memory for page_flag. %s\n",
> +					strerror(errno));
> +				return FALSE;
> +			}
> +			current = current->next;
> +		}
> +		current->next = info->page_flag_buf[i];
> +	}
> +
> +	/*
>  	 * initial fd_memory for threads
>  	 */
>  	for (i = 0; i < info->num_threads; i++) {
> @@ -3612,7 +3649,8 @@ initial_for_parallel()
>  void
>  free_for_parallel()
>  {
> -	int i;
> +	int i, j;
> +	struct page_flag *current;
>  
>  	if (info->threads != NULL) {
>  		for (i = 0; i < info->num_threads; i++) {
> @@ -3655,6 +3693,19 @@ free_for_parallel()
>  		free(info->page_data_buf);
>  	}
>  
> +	if (info->page_flag_buf != NULL) {
> +		for (i = 0; i < info->num_threads; i++) {
> +			for (j = 0; j < NUM_BUFFERS; j++) {
> +				if (info->page_flag_buf[i] != NULL) {
> +					current = info->page_flag_buf[i];
> +					info->page_flag_buf[i] = current->next;
> +					free(current);
> +				}
> +			}
> +		}
> +		free(info->page_flag_buf);
> +	}
> +
>  	if (info->parallel_info == NULL)
>  		return;
>  
> @@ -7075,11 +7126,11 @@ void *
>  kdump_thread_function_cyclic(void *arg) {
>  	void *retval = PTHREAD_FAIL;
>  	struct thread_args *kdump_thread_args = (struct thread_args *)arg;
> -	struct page_data *page_data_buf = kdump_thread_args->page_data_buf;
> +	volatile struct page_data *page_data_buf = kdump_thread_args->page_data_buf;
> +	volatile struct page_flag *page_flag_buf = kdump_thread_args->page_flag_buf;
>  	struct cycle *cycle = kdump_thread_args->cycle;
> -	int page_data_num = kdump_thread_args->page_data_num;
> -	mdf_pfn_t pfn;
> -	int index;
> +	mdf_pfn_t pfn = cycle->start_pfn;
> +	int index = kdump_thread_args->thread_num;
>  	int buf_ready;
>  	int dumpable;
>  	int fd_memory = 0;
> @@ -7125,47 +7176,48 @@ kdump_thread_function_cyclic(void *arg) {
>  						kdump_thread_args->thread_num);
>  	}
>  
> -	while (1) {
> -		/* get next pfn */
> -		pthread_mutex_lock(&info->current_pfn_mutex);
> -		pfn = info->current_pfn;
> -		info->current_pfn++;
> -		pthread_mutex_unlock(&info->current_pfn_mutex);
> -
> -		if (pfn >= kdump_thread_args->end_pfn)
> -			break;
> -
> -		index = -1;
> +	/*
> +	 * filtered page won't take anything
> +	 * unfiltered zero page will only take a page_flag_buf
> +	 * unfiltered non-zero page will take a page_flag_buf and a page_data_buf
> +	 */
> +	while (pfn < cycle->end_pfn) {
>  		buf_ready = FALSE;
>  
> +		pthread_mutex_lock(&info->page_data_mutex);
> +		while (page_data_buf[index].used != FALSE) {
> +			index = (index + 1) % info->num_buffers;
> +		}
> +		page_data_buf[index].used = TRUE;
> +		pthread_mutex_unlock(&info->page_data_mutex);
> +
>  		while (buf_ready == FALSE) {
>  			pthread_testcancel();
> -
> -			index = pfn % page_data_num;
> -
> -			if (pfn - info->consumed_pfn > info->num_buffers)
> -				continue;
> -
> -			if (page_data_buf[index].ready != 0)
> +			if (page_flag_buf->ready == FLAG_READY)
>  				continue;
>  
> -			pthread_mutex_lock(&page_data_buf[index].mutex);
> -
> -			if (page_data_buf[index].ready != 0)
> -				goto unlock;
> +			/* get next dumpable pfn */
> +			pthread_mutex_lock(&info->current_pfn_mutex);
> +			for (pfn = info->current_pfn; pfn <= cycle->end_pfn; pfn++) {
> +				dumpable = is_dumpable(
> +					info->fd_bitmap ? &bitmap_parallel : info->bitmap2,
> +					pfn,
> +					cycle);
> +				if (dumpable)
> +					break;
> +			}
> +			info->current_pfn = pfn + 1;
>  
> -			buf_ready = TRUE;
> +			page_flag_buf->pfn = pfn;
> +			page_flag_buf->ready = FLAG_FILLING;
> +			pthread_mutex_unlock(&info->current_pfn_mutex);
>  
> -			page_data_buf[index].pfn = pfn;
> -			page_data_buf[index].ready = 1;
>  
> -			dumpable = is_dumpable(
> -				info->fd_bitmap ? &bitmap_parallel : info->bitmap2,
> -				pfn,
> -				cycle);
> -			page_data_buf[index].dumpable = dumpable;
> -			if (!dumpable)
> -				goto unlock;
> +			if (pfn >= cycle->end_pfn) {
> +				info->current_pfn = cycle->end_pfn;
> +				page_data_buf[index].used = FALSE;
> +				break;
> +			}
>  
>  			if (!read_pfn_parallel(fd_memory, pfn, buf,
>  					       &bitmap_memory_parallel,
> @@ -7178,11 +7230,11 @@ kdump_thread_function_cyclic(void *arg) {
>  
>  			if ((info->dump_level & DL_EXCLUDE_ZERO)
>  			    && is_zero_page(buf, info->page_size)) {
> -				page_data_buf[index].zero = TRUE;
> -				goto unlock;
> +				page_flag_buf->zero = TRUE;
> +				goto next;
>  			}
>  
> -			page_data_buf[index].zero = FALSE;
> +			page_flag_buf->zero = FALSE;
>  
>  			/*
>  			 * Compress the page data.
> @@ -7210,6 +7262,7 @@ kdump_thread_function_cyclic(void *arg) {
>  				page_data_buf[index].flags =
>  							DUMP_DH_COMPRESSED_LZO;
>  				page_data_buf[index].size  = size_out;
> +
>  				memcpy(page_data_buf[index].buf, buf_out, size_out);
>  #endif
>  #ifdef USESNAPPY
> @@ -7232,12 +7285,14 @@ kdump_thread_function_cyclic(void *arg) {
>  				page_data_buf[index].size  = info->page_size;
>  				memcpy(page_data_buf[index].buf, buf, info->page_size);
>  			}
> -unlock:
> -			pthread_mutex_unlock(&page_data_buf[index].mutex);
> +			page_flag_buf->index = index;
> +			buf_ready = TRUE;
> +next:
> +			page_flag_buf->ready = FLAG_READY;
> +			page_flag_buf = page_flag_buf->next;
>  
>  		}
>  	}
> -
>  	retval = NULL;
>  
>  fail:
> @@ -7265,14 +7320,15 @@ write_kdump_pages_parallel_cyclic(struct cache_data *cd_header,
>  	struct page_desc pd;
>  	struct timeval tv_start;
>  	struct timeval last, new;
> -	unsigned long long consuming_pfn;
>  	pthread_t **threads = NULL;
>  	struct thread_args *kdump_thread_args = NULL;
>  	void *thread_result;
> -	int page_data_num;
> +	int page_buf_num;
>  	struct page_data *page_data_buf = NULL;
>  	int i;
>  	int index;
> +	int end_count, consuming, check_count;
> +	mdf_pfn_t current_pfn, temp_pfn;
>  
>  	if (info->flag_elf_dumpfile)
>  		return FALSE;
> @@ -7284,13 +7340,6 @@ write_kdump_pages_parallel_cyclic(struct cache_data *cd_header,
>  		goto out;
>  	}
>  
> -	res = pthread_mutex_init(&info->consumed_pfn_mutex, NULL);
> -	if (res != 0) {
> -		ERRMSG("Can't initialize consumed_pfn_mutex. %s\n",
> -				strerror(res));
> -		goto out;
> -	}
> -
>  	res = pthread_mutex_init(&info->filter_mutex, NULL);
>  	if (res != 0) {
>  		ERRMSG("Can't initialize filter_mutex. %s\n", strerror(res));
> @@ -7314,36 +7363,22 @@ write_kdump_pages_parallel_cyclic(struct cache_data *cd_header,
>  	end_pfn   = cycle->end_pfn;
>  
>  	info->current_pfn = start_pfn;
> -	info->consumed_pfn = start_pfn - 1;
>  
>  	threads = info->threads;
>  	kdump_thread_args = info->kdump_thread_args;
>  
> -	page_data_num = info->num_buffers;
> +	page_buf_num = info->num_buffers;
>  	page_data_buf = info->page_data_buf;
> +	pthread_mutex_init(&info->page_data_mutex, NULL);
>  
> -	for (i = 0; i < page_data_num; i++) {
> -		/*
> -		 * producer will use pfn in page_data_buf to decide the
> -		 * consumed pfn
> -		 */
> -		page_data_buf[i].pfn = start_pfn - 1;
> -		page_data_buf[i].ready = 0;
> -		res = pthread_mutex_init(&page_data_buf[i].mutex, NULL);
> -		if (res != 0) {
> -			ERRMSG("Can't initialize mutex of page_data_buf. %s\n",
> -					strerror(res));
> -			goto out;
> -		}
> -	}
> +	for (i = 0; i < page_buf_num; i++)
> +		page_data_buf[i].used = FALSE;
>  
>  	for (i = 0; i < info->num_threads; i++) {
>  		kdump_thread_args[i].thread_num = i;
>  		kdump_thread_args[i].len_buf_out = len_buf_out;
> -		kdump_thread_args[i].start_pfn = start_pfn;
> -		kdump_thread_args[i].end_pfn = end_pfn;
> -		kdump_thread_args[i].page_data_num = page_data_num;
>  		kdump_thread_args[i].page_data_buf = page_data_buf;
> +		kdump_thread_args[i].page_flag_buf = info->page_flag_buf[i];
>  		kdump_thread_args[i].cycle = cycle;
>  
>  		res = pthread_create(threads[i], NULL,
> @@ -7356,55 +7391,94 @@ write_kdump_pages_parallel_cyclic(struct cache_data *cd_header,
>  		}
>  	}
>  
> -	consuming_pfn = start_pfn;
> -	index = -1;
> +	end_count = 0;
> +	while (1) {
> +		consuming = 0;
> +		check_count = 0;
>  
> -	gettimeofday(&last, NULL);
> +		/*
> +		 * The basic idea is producer producing page and consumer writing page.
> +		 * Each producer have a page_flag_buf list which is used for storing page's description.
> +		 * The size of page_flag_buf is little so it won't take too much memory.
> +		 * And all producers will share a page_data_buf array which is used for storing page's compressed data.
> +		 * The main thread is the consumer. It will find the next pfn and write it into file.
> +		 * The next pfn is smallest pfn in all page_flag_buf.
> +		 */
> +		gettimeofday(&last, NULL);
> +		while (1) {
> +			current_pfn = end_pfn;
>  
> -	while (consuming_pfn < end_pfn) {
> -		index = consuming_pfn % page_data_num;
> +			/*
> +			 * page_flag_buf is in circular linked list.
> +			 * The array info->page_flag_buf[] records the current page_flag_buf in each thread's
> +			 * page_flag_buf list.
> +			 * consuming is used for recording in which thread the pfn is the smallest.
> +			 * current_pfn is used for recording the value of pfn when checking the pfn.
> +			 */
> +			for (i = 0; i < info->num_threads; i++) {
> +				if (info->page_flag_buf[i]->ready == FLAG_UNUSED)
> +					continue;
> +				temp_pfn = info->page_flag_buf[i]->pfn;
>  
> -		gettimeofday(&new, NULL);
> -		if (new.tv_sec - last.tv_sec > WAIT_TIME) {
> -			ERRMSG("Can't get data of pfn %llx.\n", consuming_pfn);
> -			goto out;
> -		}
> +				/*
> +				 * count how many threads have reached the end.
> +				 */
> +				if (temp_pfn >= end_pfn) {
> +					info->page_flag_buf[i]->ready = FLAG_UNUSED;
> +					end_count++;
> +					continue;
> +				}
>  
> -		/*
> -		 * check pfn first without mutex locked to reduce the time
> -		 * trying to lock the mutex
> -		 */
> -		if (page_data_buf[index].pfn != consuming_pfn)
> -			continue;
> +				if (current_pfn < temp_pfn)
> +					continue;
>  
> -		if (pthread_mutex_trylock(&page_data_buf[index].mutex) != 0)
> -			continue;
> +				check_count++;
> +				consuming = i;
> +				current_pfn = temp_pfn;
> +			}
> +
> +			/*
> +			 * If all the threads have reached the end, we will finish writing.
> +			 */
> +			if (end_count >= info->num_threads)
> +				goto finish;
> +
> +			/*
> +			 * Since it has the probabilty that there is no page_flag_buf being ready,
> +			 * we should recheck if it happens.
> +			 */
> +			if (check_count == 0)
> +				continue;
> +
> +			/*
> +			 * If the page_flag_buf is not ready, the pfn recorded may be changed.
> +			 * So we should recheck.
> +			 */
> +			if (info->page_flag_buf[consuming]->ready != FLAG_READY) {
> +				gettimeofday(&new, NULL);
> +				if (new.tv_sec - last.tv_sec > WAIT_TIME) {
> +					ERRMSG("Can't get data of pfn.\n");
> +					goto out;
> +				}
> +				continue;
> +			}
>  
> -		/* check whether the found one is ready to be consumed */
> -		if (page_data_buf[index].pfn != consuming_pfn ||
> -		    page_data_buf[index].ready != 1) {
> -			goto unlock;
> +			if (current_pfn == info->page_flag_buf[consuming]->pfn)
> +				break;
>  		}
>  
>  		if ((num_dumped % per) == 0)
>  			print_progress(PROGRESS_COPY, num_dumped, info->num_dumpable);
>  
> -		/* next pfn is found, refresh last here */
> -		last = new;
> -		consuming_pfn++;
> -		info->consumed_pfn++;
> -		page_data_buf[index].ready = 0;
> -
> -		if (page_data_buf[index].dumpable == FALSE)
> -			goto unlock;
> -
>  		num_dumped++;
>  
> -		if (page_data_buf[index].zero == TRUE) {
> +
> +		if (info->page_flag_buf[consuming]->zero == TRUE) {
>  			if (!write_cache(cd_header, pd_zero, sizeof(page_desc_t)))
>  				goto out;
>  			pfn_zero++;
>  		} else {
> +			index = info->page_flag_buf[consuming]->index;
>  			pd.flags      = page_data_buf[index].flags;
>  			pd.size       = page_data_buf[index].size;
>  			pd.page_flags = 0;
> @@ -7420,12 +7494,12 @@ write_kdump_pages_parallel_cyclic(struct cache_data *cd_header,
>  			 */
>  			if (!write_cache(cd_page, page_data_buf[index].buf, pd.size))
>  				goto out;
> -
> +			page_data_buf[index].used = FALSE;
>  		}
> -unlock:
> -		pthread_mutex_unlock(&page_data_buf[index].mutex);
> +		info->page_flag_buf[consuming]->ready = FLAG_UNUSED;
> +		info->page_flag_buf[consuming] = info->page_flag_buf[consuming]->next;
>  	}
> -
> +finish:
>  	ret = TRUE;
>  	/*
>  	 * print [100 %]
> @@ -7463,15 +7537,8 @@ out:
>  		}
>  	}
>  
> -	if (page_data_buf != NULL) {
> -		for (i = 0; i < page_data_num; i++) {
> -			pthread_mutex_destroy(&page_data_buf[i].mutex);
> -		}
> -	}
> -
>  	pthread_rwlock_destroy(&info->usemmap_rwlock);
>  	pthread_mutex_destroy(&info->filter_mutex);
> -	pthread_mutex_destroy(&info->consumed_pfn_mutex);
>  	pthread_mutex_destroy(&info->current_pfn_mutex);
>  
>  	return ret;
> @@ -7564,6 +7631,7 @@ write_kdump_pages_cyclic(struct cache_data *cd_header, struct cache_data *cd_pag
>  		num_dumped++;
>  		if (!read_pfn(pfn, buf))
>  			goto out;
> +
>  		filter_data_buffer(buf, pfn_to_paddr(pfn), info->page_size);
>  
>  		/*
> diff --git a/makedumpfile.h b/makedumpfile.h
> index e0b5bbf..5865827 100644
> --- a/makedumpfile.h
> +++ b/makedumpfile.h
> @@ -977,7 +977,7 @@ typedef unsigned long long int ulonglong;
>  #define PAGE_DATA_NUM	(50)
>  #define WAIT_TIME	(60 * 10)
>  #define PTHREAD_FAIL	((void *)-2)
> -#define NUM_BUFFERS	(50)
> +#define NUM_BUFFERS	(20)
>  
>  struct mmap_cache {
>  	char	*mmap_buf;
> @@ -985,28 +985,33 @@ struct mmap_cache {
>  	off_t   mmap_end_offset;
>  };
>  
> +enum {
> +	FLAG_UNUSED,
> +	FLAG_READY,
> +	FLAG_FILLING
> +};
> +struct page_flag {
> +	mdf_pfn_t pfn;
> +	char zero;
> +	char ready;
> +	short index;
> +	struct page_flag *next;
> +};
> +
>  struct page_data
>  {
> -	mdf_pfn_t pfn;
> -	int dumpable;
> -	int zero;
> -	unsigned int flags;
>  	long size;
>  	unsigned char *buf;
> -	pthread_mutex_t mutex;
> -	/*
> -	 * whether the page_data is ready to be consumed
> -	 */
> -	int ready;
> +	int flags;
> +	int used;
>  };
>  
>  struct thread_args {
>  	int thread_num;
>  	unsigned long len_buf_out;
> -	mdf_pfn_t start_pfn, end_pfn;
> -	int page_data_num;
>  	struct cycle *cycle;
>  	struct page_data *page_data_buf;
> +	struct page_flag *page_flag_buf;
>  };
>  
>  /*
> @@ -1295,11 +1300,11 @@ struct DumpInfo {
>  	pthread_t **threads;
>  	struct thread_args *kdump_thread_args;
>  	struct page_data *page_data_buf;
> +	struct page_flag **page_flag_buf;
>  	pthread_rwlock_t usemmap_rwlock;
>  	mdf_pfn_t current_pfn;
>  	pthread_mutex_t current_pfn_mutex;
> -	mdf_pfn_t consumed_pfn;
> -	pthread_mutex_t consumed_pfn_mutex;
> +	pthread_mutex_t page_data_mutex;
>  	pthread_mutex_t filter_mutex;
>  };
>  extern struct DumpInfo		*info;
> -- 
> 1.8.3.1
> 
> 
> 
> 
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