Hello,
Several weeks ago, we talked about the performance degradation of --num-threads 1.
I found in the origin implementation, handling filtered page and zero page spends more
time than without num-threads.
I think that's why --num-threads 1 is so different from --num-threads 0.
I rewrite the logic in this patch. And the new implementation can resolve the degradation
of -d 31. It can reduce the time of handling filtered page.
But it seems not effective for handling zero page.
--
Thanks
Zhou
On 01/18/2016 10:00 AM, Zhou Wenjian wrote:
> The origin implementation of --num-threads wastes a lot of time
> dealing with the filtered pages. So it has a great performance degradation
> when -d 31 is specified.
> 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.
> It won't waste time and memory for filtered page. So it has a good behaviour in -d 31.
>
> Some tests results:
>
> -l -c
> -d 31: 2.6 11.3 (without num-threads)
> num-threads origin new origin new
> 1 13.2 2.9 22.4 13.2
> 2 11.6 2.46 15.3 7.3
> 4 10.4 3.2 12.3 5.7
> -d 0: 32.7 151.2(without num-threads)
> 1 43.3 45.3 158.9 159.4
> 2 21.2 23.0 81.8 83.2
> 4 18.2 21.4 46.1 47.5
>
> These tests are executed in the second kernel with /proc/vmcore.
> ---
> makedumpfile.c | 266 +++++++++++++++++++++++++++++++++++++++------------------
> makedumpfile.h | 26 +++---
> 2 files changed, 196 insertions(+), 96 deletions(-)
>
> diff --git a/makedumpfile.c b/makedumpfile.c
> index fa0b779..8cf274b 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) {
> + 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;
> + }
> + 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 +7172,48 @@ 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);
> + /* 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) {
> + 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;
>
> 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)
> + /* 1 means page_flag_buf is ready to be used */
> + if (page_flag_buf->ready == 1)
> 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++;
> + /* 2 means page_flag_buf is being filled */
> + page_flag_buf->ready = 2;
> + pthread_mutex_unlock(&info->current_pfn_mutex);
>
> - if (page_data_buf[index].ready != 0)
> - goto unlock;
> + page_flag_buf->pfn = 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 = 1;
> + info->current_pfn--;
> + break;
> + }
>
> 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 +7226,11 @@ 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.
> @@ -7232,12 +7280,16 @@ 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 = 1;
> + page_flag_buf = page_flag_buf->next;
>
> }
> - }
>
> + pthread_mutex_unlock(&page_data_buf[index].mutex);
> + }
> retval = NULL;
>
> fail:
> @@ -7265,14 +7317,15 @@ 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 +7372,11 @@ 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 +7390,9 @@ 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 +7405,101 @@ write_kdump_pages_parallel_cyclic(struct cache_data *cd_header,
> }
> }
>
> - consuming_pfn = start_pfn;
> - index = -1;
> + 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.
> + */
> + /*
> + *
> + */
> + while (1) {
> + current_pfn = end_pfn;
> + end_count = 0;
>
> - 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++) {
>
> - 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;
> - }
> + /*
> + * ready == 0 means the page_flag_buf haven't been used.
> + * So we will skip it.
> + */
> + if (info->page_flag_buf[i]->ready == 0)
> + continue;
> + temp_pfn = info->page_flag_buf[i]->pfn;
>
> - /*
> - * check pfn first without mutex locked to reduce the time
> - * trying to lock the mutex
> - */
> - if (page_data_buf[index].pfn != consuming_pfn)
> - continue;
> + /*
> + * count how many threads have reached the end.
> + */
> + if (temp_pfn >= end_pfn) {
> + end_count++;
> + continue;
> + }
>
> - if (pthread_mutex_trylock(&page_data_buf[index].mutex) != 0)
> - continue;
> + if (current_pfn < temp_pfn)
> + 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;
> + 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 != 1) {
> + gettimeofday(&new, NULL);
> + if (new.tv_sec - last.tv_sec > WAIT_TIME) {
> + ERRMSG("Can't get data of pfn.\n");
> + goto out;
> + }
> + }
> +
> + 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 +7515,12 @@ 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 = 0;
> + info->page_flag_buf[consuming] = info->page_flag_buf[consuming]->next;
> }
> -
> +finish:
> ret = TRUE;
> /*
> * print [100 %]
> @@ -7464,7 +7559,7 @@ 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 +7659,7 @@ 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..7452e24 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 +985,31 @@ struct mmap_cache {
> off_t mmap_end_offset;
> };
>
> +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 +1298,7 @@ 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;
>
