Hi, Zhou I have some comments. I'm sorry if I have misunderstood your code. > -----Original Message----- > From: kexec [mailto:kexec-bounces at lists.infradead.org] On Behalf Of Zhou Wenjian > Sent: Monday, February 01, 2016 3:22 PM > To: kexec at lists.infradead.org > Subject: [PATCH v1] Improve the performance of --num-threads -d 31 > > v1: > 1. change page_flag.ready's value to enum > 2. change the patch description > 3. cleanup some codes > 4. fix a bug in cyclic mode > > 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: Zhou Wenjian <zhouwj-fnst at cn.fujitsu.com> > --- > makedumpfile.c | 258 ++++++++++++++++++++++++++++++++++++++------------------- > makedumpfile.h | 31 ++++--- > 2 files changed, 193 insertions(+), 96 deletions(-) > > diff --git a/makedumpfile.c b/makedumpfile.c > index fa0b779..0ecd065 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); > > @@ -3562,8 +3563,10 @@ initial_for_parallel() > - MAP_REGION * info->num_threads) * 0.6; > > 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 +3591,36 @@ 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] = malloc(sizeof(struct page_flag))) == NULL) { Fist element of struct page_flag in circular list is allocated by malloc(), but other elements are allocated by calloc().(see below) I think both elements should be allocated by calloc(). > + MSG("Can't allocate memory for page_flag_buf. %s\n", > + strerror(errno)); > + return FALSE; > + } > + current = info->page_flag_buf[i]; > + > + for (j = 1; j < NUM_BUFFERS; j++) { > + if ((current->next = calloc(0, sizeof(struct page_flag))) == NULL) { > + MSG("Can't allocate memory for data of page_data_buf. %s\n", > + strerror(errno)); > + return FALSE; > + } First argument of calloc() should be 1, not 0. And there is typo in error message. Allocated element is not page_data_buf. > + 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 +3645,8 @@ 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 +3689,19 @@ 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; > > @@ -7076,10 +7123,10 @@ 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; > + 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; > + int index = kdump_thread_args->thread_num; > int buf_ready; > int dumpable; > int fd_memory = 0; > @@ -7125,47 +7172,47 @@ 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); > + /* > + * 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 (page_flag_buf->pfn < kdump_thread_args->end_pfn) { At first, page_flag_buf->pfn is not initialized. I think this block should be replaced with the following code. === do { : } while(page_flag_buf->pfn < kdump_thread_args->end_pfn) === > + buf_ready = FALSE; > > - if (pfn >= kdump_thread_args->end_pfn) > - break; > + while (page_data_buf[index].used != 0 || > + pthread_mutex_trylock(&page_data_buf[index].mutex) != 0) > + index = (index + 1) % info->num_buffers; > > - index = -1; > - buf_ready = FALSE; > + page_data_buf[index].used = 1; "1" is a magic number. It should be changed TRUE or FALSE. > 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; At first, page_flag_buf->ready is uninitialized, too. Should it be initialized in head part of this function, even if FLAG_UNUSED is defined 0? > > - if (page_data_buf[index].ready != 0) > - continue; > - > - pthread_mutex_lock(&page_data_buf[index].mutex); > + /* get next pfn */ > + pthread_mutex_lock(&info->current_pfn_mutex); > + pfn = info->current_pfn; > + info->current_pfn++; > + page_flag_buf->ready = FLAG_FILLING; > + pthread_mutex_unlock(&info->current_pfn_mutex); > > - if (page_data_buf[index].ready != 0) > - goto unlock; > + page_flag_buf->pfn = pfn; It set FLAG_FILLING to page_flag_buf->ready before setting pfn to page_flag_buf->pfn. But consumer gets page_flag_buf->pfn after checking page_flag_buf->ready != FLAG_UNUSED in getting minimum pfn of each thread block. Should it set page_flag_buf->pfn first? > > - buf_ready = TRUE; > - > - page_data_buf[index].pfn = pfn; > - page_data_buf[index].ready = 1; > + if (pfn >= kdump_thread_args->end_pfn) { > + page_data_buf[index].used = 0; > + page_flag_buf->ready = FLAG_READY; > + info->current_pfn--; > + break; > + } This block decrements info->current_pfn without info->current_pfn_mutex. I think this block should be moved into previous pthread_mutex_lock(info->current_pfn_mutex) block, so it can remove. > > dumpable = is_dumpable( > info->fd_bitmap ? &bitmap_parallel : info->bitmap2, > pfn, > cycle); > - page_data_buf[index].dumpable = dumpable; > if (!dumpable) > - goto unlock; > + continue; > > if (!read_pfn_parallel(fd_memory, pfn, buf, > &bitmap_memory_parallel, > @@ -7178,11 +7225,11 @@ 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; > } First, this code gets page_data_buf, then it gets page_flag_buf. However, if processed pfn is zero page, it processes next pfn while keeping page_data_buf. I think it should get page_flag_buf, then get page_data_buf in order to shorten the holding period of the page_data_buf[index].mutex. Thanks, Minoru Usui > > - page_data_buf[index].zero = FALSE; > + page_flag_buf->zero = FALSE; > > /* > * Compress the page data. > @@ -7232,12 +7279,16 @@ 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; > > } > - } > > + pthread_mutex_unlock(&page_data_buf[index].mutex); > + } > retval = NULL; > > fail: > @@ -7265,14 +7316,15 @@ 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; > @@ -7319,16 +7371,11 @@ write_kdump_pages_parallel_cyclic(struct cache_data *cd_header, > 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; > > - 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; > + for (i = 0; i < page_buf_num; i++) { > + page_data_buf[i].used = 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", > @@ -7342,8 +7389,9 @@ write_kdump_pages_parallel_cyclic(struct cache_data *cd_header, > 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_buf_num = page_buf_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 +7404,94 @@ write_kdump_pages_parallel_cyclic(struct cache_data *cd_header, > } > } > > - consuming_pfn = start_pfn; > - index = -1; > + while (1) { > + consuming = 0; > + check_count = 0; > + end_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. > + */ > + 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) { > + end_count++; > + info->page_flag_buf[i]->ready = FLAG_UNUSED; > + 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; > + > + /* > + * When we check the pfn in page_flag_buf, it may be being produced. > + * So we should wait until it is ready to use. And if the pfn is > + * different from the value when we check, we should rechoose the buf. > + */ > + gettimeofday(&last, NULL); > + while (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; > + } > + } > > - /* 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 +7507,12 @@ 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 = 0; > } > -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 %] > @@ -7464,7 +7551,7 @@ out: > } > > if (page_data_buf != NULL) { > - for (i = 0; i < page_data_num; i++) { > + for (i = 0; i < page_buf_num; i++) { > pthread_mutex_destroy(&page_data_buf[i].mutex); > } > } > @@ -7564,6 +7651,7 @@ 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..8a9a5b2 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 +985,36 @@ 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; > + pthread_mutex_t mutex; > 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; > + int page_buf_num; > struct cycle *cycle; > struct page_data *page_data_buf; > + struct page_flag *page_flag_buf; > }; > > /* > @@ -1295,6 +1303,7 @@ 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; > -- > 1.8.3.1 > > > > > _______________________________________________ > kexec mailing list > kexec at lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec
