Hello Usui, Thanks very much for your comments. And sorry for the late reply. See below. On 02/08/2016 01:00 PM, Minoru Usui wrote: > Hello, > >> -----Original Message----- >> From: kexec [mailto:kexec-bounces at lists.infradead.org] On Behalf Of Minoru Usui >> Sent: Thursday, February 04, 2016 8:52 AM >> To: Zhou Wenjian <zhouwj-fnst at cn.fujitsu.com>; kexec at lists.infradead.org >> Subject: Re: [PATCH v1] Improve the performance of --num-threads -d 31 >> >> 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(). >> Yes, you are right. I have made a mistake. >>> + 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. >> I agree. >>> + 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) >> === > > I'm sorry, above suggestion is meaningless in terms of page_flag_buf->pfn is uninitialized. > It should be replaced like following. > > === > while (1) { > : > while (buf_ready == FALSE) { > : > if (pfn >= kdump_thread_args->end_pfn) { > : > goto finish; > } > : > } > : > } > finish: > === > page_flag_buf is allocated by calloc(). The page_flag_buf->pfn's value is 0. So I think it is not necessary to modify the code. > Thanks, > Minoru Usui > > >>> + 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. >> I see. >>> 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? >> >> The same topic as the page_flag_buf is allocated by calloc(). >>> >>> - 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? >> Have you noticed the following code in the consumer? <cut> if (current_pfn == info->page_flag_buf[consuming]->pfn) break; <cut> The consumer will check if the pfn is changed after the page_flag_buf->ready turns to be FLAG_READY. So it's not important whether setting page_flag_buf->pfn first or not. In the other hand, even setting page_flag_buf->pfn first, if the pfn is not dumpable, the producer will also reset the page_flag_buf->pfn. >>> >>> - 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. >> Why do you think it should have current_pfn_mutex? If pfn >= kdump_thread_args->end_pfn, info->current_pfn will always larger than kdump_thread_args->end_pfn. info->current_pfn-- won't affect anything. The decrement operation is for cyclic mode. >>> >>> 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. >> Do you mean the following logic? 1. get the page_flag_buf first 2. if the pfn is not zero page, then get the page_data_buf. Think about the following case. A producer get the page_flag_buf, and the pfn is not zero page. It wants to get a page_data_buf, but there is no more page_data_buf. Then ... Since there are several page_data_bufs, it's not a problem that each producer will always hold a page_data_buf. Thanks again for your comments. And I will post the next version later. -- Thanks Zhou >> 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 >> >> _______________________________________________ >> kexec mailing list >> kexec at lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/kexec > >
