[PATCH v4] Improve the performance of --num-threads -d 31

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On 03/11/16 at 09:00am, "Zhou, Wenjian/???" wrote:
> Hello all,
> 
> Do you have any comments ?

Hi, Wenjian.

I will test this patch, and update the result in several days, since the
machine has been loaned to other developer.

Thanks
Minfei

> 
> -- 
> Thanks
> Zhou
> 
> On 03/09/2016 08:27 AM, Zhou Wenjian wrote:
> >v4:
> >         1. fix a bug caused by the logic
> >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 | 298 +++++++++++++++++++++++++++++++++++----------------------
> >  makedumpfile.h |  35 ++++---
> >  2 files changed, 202 insertions(+), 131 deletions(-)
> >
> >diff --git a/makedumpfile.c b/makedumpfile.c
> >index fa0b779..2b0864a 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)
> >+			if (page_flag_buf->ready == FLAG_READY)
> >  				continue;
> >
> >-			if (page_data_buf[index].ready != 0)
> >-				continue;
> >-
> >-			pthread_mutex_lock(&page_data_buf[index].mutex);
> >-
> >-			if (page_data_buf[index].ready != 0)
> >-				goto unlock;
> >-
> >-			buf_ready = TRUE;
> >+			/* 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;
> >
> >-			page_data_buf[index].pfn = pfn;
> >-			page_data_buf[index].ready = 1;
> >+			page_flag_buf->pfn = pfn;
> >+			page_flag_buf->ready = FLAG_FILLING;
> >+			pthread_mutex_unlock(&info->current_pfn_mutex);
> >+			sem_post(&info->page_flag_buf_sem);
> >
> >-			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 +7363,23 @@ 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);
> >+	sem_init(&info->page_flag_buf_sem, 0, 0);
> >
> >-	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 +7392,88 @@ 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.
> >+		 */
> >+		sem_wait(&info->page_flag_buf_sem);
> >+		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;
> >+			}
> >
> >-		/* 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 all the threads have reached the end, we will finish writing.
> >+			 */
> >+			if (end_count >= info->num_threads)
> >+				goto finish;
> >+
> >+			/*
> >+			 * 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;
> >+			}
> >+
> >+			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 +7489,12 @@ 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 +7532,9 @@ out:
> >  		}
> >  	}
> >
> >-	if (page_data_buf != NULL) {
> >-		for (i = 0; i < page_data_num; i++) {
> >-			pthread_mutex_destroy(&page_data_buf[i].mutex);
> >-		}
> >-	}
> >-
> >+	sem_destroy(&info->page_flag_buf_sem);
> >  	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 +7627,7 @@ 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..4b315c0 100644
> >--- a/makedumpfile.h
> >+++ b/makedumpfile.h
> >@@ -44,6 +44,7 @@
> >  #include "print_info.h"
> >  #include "sadump_mod.h"
> >  #include <pthread.h>
> >+#include <semaphore.h>
> >
> >  /*
> >   * Result of command
> >@@ -977,7 +978,7 @@ 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 +986,33 @@ 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 +1301,12 @@ struct DumpInfo {
> >  	pthread_t **threads;
> >  	struct thread_args *kdump_thread_args;
> >  	struct page_data *page_data_buf;
> >+	struct page_flag **page_flag_buf;
> >+	sem_t page_flag_buf_sem;
> >  	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;
> >
> 
> 
> 
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> kexec at lists.infradead.org
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