[PATCH v3] Improve the performance of --num-threads -d 31
"Zhou, Wenjian/周文剑"
zhouwj-fnst at cn.fujitsu.com
Fri Mar 4 01:07:53 PST 2016
Hello Minfei and Minoru,
This is a reply to the previous letters.
Sorry for so late.
And it is also an introduction of the patch v3.
About performance:
I modified the patch after reading Minoru's code.
Thanks Minoru, it has better performance now.
About bugs:
There are two bugs in the patch v2.
First is reported by Minfei.
Minoru's explanation and solution are right.
But I used another solution.
+ if (pfn >= kdump_thread_args->end_pfn) {
+ page_data_buf[index].used = FALSE;
+ page_flag_buf->ready = FLAG_READY;
+ break;
+ }
The bug is caused by the above code.
Just remove "page_flag_buf->ready = FLAG_READY;" is OK.
Second bug is what I met.
If run makedumpfile a lot of times, a few pages' data will not be correct.
I fix it by using "volatile" and info->page_data_mutex.
So I delete the original mutex in page_data_buf. It can also use less memory.
I have run it 500 times and haven't got any wrong page data.
--
Thanks
Zhou
On 03/04/2016 04:35 PM, 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;
>
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