On 08/04/2016 08:50 AM, Atsushi Kumagai wrote:
> Hello Zhou,
>
>> Currently, num_threads means the producer number. The main thread
>> is not included. However, num_threads is specified by the option
>> "--num-threads". So this may make user confused why it still has
>> performance degradation when the value by "--num-threads" equals
>> the usable cpu number.
>>
>> I think it will be more nature to make "--num-threads" be producer
>> number + 1. In other words, "--num-threads" should include the
>> main thread.
>
> The most part of cpu time will be spent for compression while
> the main thread(Consumer) just does I/O work.
> If the usable cpu number is 2 and --num-thread is also 2, your
> patch reserves a whole cpu for the main thread and the compression
> will be done by just one cpu. Is that really the multi thread
> processing which we wanted ?
>
> If there are 4 usable cpus, I guess 4 producers with the main thread
> is faster than 3 producers with the main thread.
>
> However, according to my quick test, there were no significant
> differences between the two cases.
> (This was measured on a small VM(5GB) without your patch, the number
> of trials is 3, so just for information.)
>
> # makedumpfile -c --num-thread [3|4]
>
> | | time[s]
> CPUs | -num-threads | 1st | 2nd | 3rd
> -------+---------------+----------+----------+----------
> 4 | 3 | 29.54 30.19 28.26
> 4 | 4 | 29.80 31.75 28.19
>
> Then, I noticed that the cpu usage of the main thread is almost 100%
> while it doesn't need a lot of cpu resources in theory. Do you have
> any idea why the main thread require a lot of cpu resources ?
Yes, it shouldn't take so much cpu time.
It really need to be improved.
I'll think about it.
--
Thanks
Zhou
> If it's an unintended behavior, I believe the case of --num-thread=4
> can be faster if the cpu usage of the main thread is reduced.
>
>
> Thanks,
> Atsushi Kumagai
>
>> ---
>> makedumpfile.c | 108
>> ++++++++++++++++++++++++++++-----------------------------
>> makedumpfile.h | 4 +--
>> 2 files changed, 56 insertions(+), 56 deletions(-)
>>
>> diff --git a/makedumpfile.c b/makedumpfile.c
>> index 21784e8..19019a4 100644
>> --- a/makedumpfile.c
>> +++ b/makedumpfile.c
>> @@ -1407,13 +1407,13 @@ open_dump_bitmap(void)
>> }
>> }
>>
>> - if (info->num_threads) {
>> + if (info->num_producers) {
>> /*
>> * Reserve file descriptors of bitmap for creating dumpfiles
>> * parallelly, because a bitmap file will be unlinked just after
>> * this and it is not possible to open a bitmap file later.
>> */
>> - for (i = 0; i < info->num_threads; i++) {
>> + for (i = 0; i < info->num_producers; i++) {
>> if ((fd = open(info->name_bitmap, O_RDONLY)) < 0) {
>> ERRMSG("Can't open the bitmap file(%s). %s\n",
>> info->name_bitmap, strerror(errno));
>> @@ -3495,9 +3495,9 @@ initialize_bitmap_memory(void)
>> }
>>
>> void
>> -initialize_bitmap_memory_parallel(struct dump_bitmap *bitmap, int
>> thread_num)
>> +initialize_bitmap_memory_parallel(struct dump_bitmap *bitmap, int
>> producer_num)
>> {
>> - bitmap->fd = FD_BITMAP_MEMORY_PARALLEL(thread_num);
>> + bitmap->fd = FD_BITMAP_MEMORY_PARALLEL(producer_num);
>> bitmap->file_name = info->name_memory;
>> bitmap->no_block = -1;
>> memset(bitmap->buf, 0, BUFSIZE_BITMAP);
>> @@ -3529,24 +3529,24 @@ initial_for_parallel()
>> /*
>> * allocate memory for threads
>> */
>> - if ((info->threads = malloc(sizeof(pthread_t *) * info->num_threads))
>> + if ((info->threads = malloc(sizeof(pthread_t *) * info->num_producers))
>> == NULL) {
>> MSG("Can't allocate memory for threads. %s\n",
>> strerror(errno));
>> return FALSE;
>> }
>> - memset(info->threads, 0, sizeof(pthread_t *) * info->num_threads);
>> + memset(info->threads, 0, sizeof(pthread_t *) * info->num_producers);
>>
>> if ((info->kdump_thread_args =
>> - malloc(sizeof(struct thread_args) * info->num_threads))
>> + malloc(sizeof(struct thread_args) *
>> info->num_producers))
>> == NULL) {
>> MSG("Can't allocate memory for arguments of threads. %s\n",
>> strerror(errno));
>> return FALSE;
>> }
>> - memset(info->kdump_thread_args, 0, sizeof(struct thread_args) *
>> info->num_threads);
>> + memset(info->kdump_thread_args, 0, sizeof(struct thread_args) *
>> info->num_producers);
>>
>> - for (i = 0; i < info->num_threads; i++) {
>> + for (i = 0; i < info->num_producers; i++) {
>> if ((info->threads[i] = malloc(sizeof(pthread_t))) == NULL) {
>> MSG("Can't allocate memory for thread %d. %s",
>> i, strerror(errno));
>> @@ -3592,7 +3592,7 @@ initial_for_parallel()
>> #endif
>> }
>>
>> - info->num_buffers = PAGE_DATA_NUM * info->num_threads;
>> + info->num_buffers = PAGE_DATA_NUM * info->num_producers;
>>
>> /*
>> * allocate memory for page_data
>> @@ -3615,17 +3615,17 @@ initial_for_parallel()
>> }
>>
>> /*
>> - * initial page_flag for each thread
>> + * initial page_flag for each producer thread
>> */
>> - if ((info->page_flag_buf = malloc(sizeof(void *) * info->num_threads))
>> + if ((info->page_flag_buf = malloc(sizeof(void *) * info->num_producers))
>> == 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);
>> + memset(info->page_flag_buf, 0, sizeof(void *) * info->num_producers);
>>
>> - for (i = 0; i < info->num_threads; i++) {
>> + for (i = 0; i < info->num_producers; 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));
>> @@ -3645,9 +3645,9 @@ initial_for_parallel()
>> }
>>
>> /*
>> - * initial fd_memory for threads
>> + * initial fd_memory for producer threads
>> */
>> - for (i = 0; i < info->num_threads; i++) {
>> + for (i = 0; i < info->num_producers; i++) {
>> if ((FD_MEMORY_PARALLEL(i) = open(info->name_memory, O_RDONLY))
>> < 0) {
>> ERRMSG("Can't open the dump memory(%s). %s\n",
>> @@ -3673,7 +3673,7 @@ free_for_parallel()
>> struct page_flag *current;
>>
>> if (info->threads != NULL) {
>> - for (i = 0; i < info->num_threads; i++) {
>> + for (i = 0; i < info->num_producers; i++) {
>> if (info->threads[i] != NULL)
>> free(info->threads[i]);
>>
>> @@ -3714,7 +3714,7 @@ free_for_parallel()
>> }
>>
>> if (info->page_flag_buf != NULL) {
>> - for (i = 0; i < info->num_threads; i++) {
>> + for (i = 0; i < info->num_producers; i++) {
>> for (j = 0; j < PAGE_FLAG_NUM; j++) {
>> if (info->page_flag_buf[i] != NULL) {
>> current = info->page_flag_buf[i];
>> @@ -3729,7 +3729,7 @@ free_for_parallel()
>> if (info->parallel_info == NULL)
>> return;
>>
>> - for (i = 0; i < info->num_threads; i++) {
>> + for (i = 0; i < info->num_producers; i++) {
>> if (FD_MEMORY_PARALLEL(i) > 0)
>> close(FD_MEMORY_PARALLEL(i));
>>
>> @@ -3936,7 +3936,7 @@ out:
>> DEBUG_MSG("Buffer size for the cyclic mode: %ld\n",
>> info->bufsize_cyclic);
>> }
>>
>> - if (info->num_threads) {
>> + if (info->num_producers) {
>> if (is_xen_memory()) {
>> MSG("'--num-threads' option is disable,\n");
>> MSG("because %s is Xen's memory core image.\n",
>> @@ -4066,9 +4066,9 @@ initialize_2nd_bitmap(struct dump_bitmap *bitmap)
>> }
>>
>> void
>> -initialize_2nd_bitmap_parallel(struct dump_bitmap *bitmap, int thread_num)
>> +initialize_2nd_bitmap_parallel(struct dump_bitmap *bitmap, int producer_num)
>> {
>> - bitmap->fd = FD_BITMAP_PARALLEL(thread_num);
>> + bitmap->fd = FD_BITMAP_PARALLEL(producer_num);
>> bitmap->file_name = info->name_bitmap;
>> bitmap->no_block = -1;
>> memset(bitmap->buf, 0, BUFSIZE_BITMAP);
>> @@ -7558,7 +7558,7 @@ kdump_thread_function_cyclic(void *arg) {
>> volatile struct page_flag *page_flag_buf =
>> kdump_thread_args->page_flag_buf;
>> struct cycle *cycle = kdump_thread_args->cycle;
>> mdf_pfn_t pfn = cycle->start_pfn;
>> - int index = kdump_thread_args->thread_num;
>> + int index = kdump_thread_args->producer_num;
>> int buf_ready;
>> int dumpable;
>> int fd_memory = 0;
>> @@ -7566,21 +7566,21 @@ kdump_thread_function_cyclic(void *arg) {
>> struct dump_bitmap bitmap_memory_parallel = {0};
>> unsigned char *buf = NULL, *buf_out = NULL;
>> struct mmap_cache *mmap_cache =
>> - MMAP_CACHE_PARALLEL(kdump_thread_args->thread_num);
>> + MMAP_CACHE_PARALLEL(kdump_thread_args->producer_num);
>> unsigned long size_out;
>> - z_stream *stream = &ZLIB_STREAM_PARALLEL(kdump_thread_args->thread_num);
>> + z_stream *stream =
>> &ZLIB_STREAM_PARALLEL(kdump_thread_args->producer_num);
>> #ifdef USELZO
>> - lzo_bytep wrkmem = WRKMEM_PARALLEL(kdump_thread_args->thread_num);
>> + lzo_bytep wrkmem = WRKMEM_PARALLEL(kdump_thread_args->producer_num);
>> #endif
>> #ifdef USESNAPPY
>> unsigned long len_buf_out_snappy =
>> snappy_max_compressed_length(info->page_size);
>> #endif
>>
>> - buf = BUF_PARALLEL(kdump_thread_args->thread_num);
>> - buf_out = BUF_OUT_PARALLEL(kdump_thread_args->thread_num);
>> + buf = BUF_PARALLEL(kdump_thread_args->producer_num);
>> + buf_out = BUF_OUT_PARALLEL(kdump_thread_args->producer_num);
>>
>> - fd_memory = FD_MEMORY_PARALLEL(kdump_thread_args->thread_num);
>> + fd_memory = FD_MEMORY_PARALLEL(kdump_thread_args->producer_num);
>>
>> if (info->fd_bitmap) {
>> bitmap_parallel.buf = malloc(BUFSIZE_BITMAP);
>> @@ -7590,7 +7590,7 @@ kdump_thread_function_cyclic(void *arg) {
>> goto fail;
>> }
>> initialize_2nd_bitmap_parallel(&bitmap_parallel,
>> - kdump_thread_args->thread_num);
>> + kdump_thread_args->producer_num);
>> }
>>
>> if (info->flag_refiltering) {
>> @@ -7601,7 +7601,7 @@ kdump_thread_function_cyclic(void *arg) {
>> goto fail;
>> }
>> initialize_bitmap_memory_parallel(&bitmap_memory_parallel,
>> - kdump_thread_args->thread_num);
>> +
>> kdump_thread_args->producer_num);
>> }
>>
>> /*
>> @@ -7802,8 +7802,8 @@ write_kdump_pages_parallel_cyclic(struct cache_data
>> *cd_header,
>> 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;
>> + for (i = 0; i < info->num_producers; i++) {
>> + kdump_thread_args[i].producer_num = i;
>> kdump_thread_args[i].len_buf_out = len_buf_out;
>> kdump_thread_args[i].page_data_buf = page_data_buf;
>> kdump_thread_args[i].page_flag_buf = info->page_flag_buf[i];
>> @@ -7843,13 +7843,13 @@ write_kdump_pages_parallel_cyclic(struct cache_data
>> *cd_header,
>> * 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++) {
>> + for (i = 0; i < info->num_producers; i++) {
>> if (info->page_flag_buf[i]->ready ==
>> FLAG_UNUSED)
>> continue;
>> temp_pfn = info->page_flag_buf[i]->pfn;
>>
>> /*
>> - * count how many threads have reached the end.
>> + * count how many producer threads have reached
>> the end.
>> */
>> if (temp_pfn >= end_pfn) {
>> info->page_flag_buf[i]->ready =
>> FLAG_UNUSED;
>> @@ -7865,9 +7865,9 @@ write_kdump_pages_parallel_cyclic(struct cache_data
>> *cd_header,
>> }
>>
>> /*
>> - * If all the threads have reached the end, we will
>> finish writing.
>> + * If all producer threads have reached the end, we
>> will finish writing.
>> */
>> - if (end_count >= info->num_threads)
>> + if (end_count >= info->num_producers)
>> goto finish;
>>
>> /*
>> @@ -7930,7 +7930,7 @@ finish:
>>
>> out:
>> if (threads != NULL) {
>> - for (i = 0; i < info->num_threads; i++) {
>> + for (i = 0; i < info->num_producers; i++) {
>> if (threads[i] != NULL) {
>> res = pthread_cancel(*threads[i]);
>> if (res != 0 && res != ESRCH)
>> @@ -7939,7 +7939,7 @@ out:
>> }
>> }
>>
>> - for (i = 0; i < info->num_threads; i++) {
>> + for (i = 0; i < info->num_producers; i++) {
>> if (threads[i] != NULL) {
>> res = pthread_join(*threads[i], &thread_result);
>> if (res != 0)
>> @@ -8553,7 +8553,7 @@ write_kdump_pages_and_bitmap_cyclic(struct cache_data
>> *cd_header, struct cache_d
>> if (!write_kdump_bitmap2(&cycle))
>> return FALSE;
>>
>> - if (info->num_threads) {
>> + if (info->num_producers) {
>> if (!write_kdump_pages_parallel_cyclic(cd_header,
>> cd_page, &pd_zero,
>> &offset_data, &cycle))
>> @@ -10531,7 +10531,7 @@ check_param_for_creating_dumpfile(int argc, char
>> *argv[])
>> if (info->flag_sadump_diskset && !sadump_is_supported_arch())
>> return FALSE;
>>
>> - if (info->num_threads) {
>> + if (info->num_producers) {
>> if (info->flag_split) {
>> MSG("--num-threads cannot used with --split.\n");
>> return FALSE;
>> @@ -10607,16 +10607,16 @@ check_param_for_creating_dumpfile(int argc, char
>> *argv[])
>> } else
>> return FALSE;
>>
>> - if (info->num_threads) {
>> + if (info->num_producers) {
>> if ((info->parallel_info =
>> - malloc(sizeof(parallel_info_t) * info->num_threads))
>> + malloc(sizeof(parallel_info_t) * info->num_producers))
>> == NULL) {
>> MSG("Can't allocate memory for parallel_info.\n");
>> return FALSE;
>> }
>>
>> memset(info->parallel_info, 0, sizeof(parallel_info_t)
>> - * info->num_threads);
>> + * info->num_producers);
>> }
>>
>> return TRUE;
>> @@ -10721,20 +10721,20 @@ calculate_cyclic_buffer_size(void) {
>> limit_size = get_free_memory_size() * 0.6;
>>
>> /*
>> - * Recalculate the limit_size according to num_threads.
>> - * And reset num_threads if there is not enough memory.
>> + * Recalculate the limit_size according to num_producers.
>> + * And reset --num-threads if there is not enough memory.
>> */
>> - if (info->num_threads > 0) {
>> + if (info->num_producers > 0) {
>> if (limit_size <= maximum_size) {
>> MSG("There isn't enough memory for multi-threads.\n");
>> - info->num_threads = 0;
>> + info->num_producers = 0;
>> }
>> - else if ((limit_size - maximum_size) / info->num_threads <
>> THREAD_REGION) {
>> - MSG("There isn't enough memory for %d threads.\n",
>> info->num_threads);
>> - info->num_threads = (limit_size - maximum_size) /
>> THREAD_REGION;
>> - MSG("--num_threads is set to %d.\n", info->num_threads);
>> + else if ((limit_size - maximum_size) / info->num_producers <
>> THREAD_REGION) {
>> + MSG("There isn't enough memory for %d threads.\n",
>> info->num_producers + 1);
>> + info->num_producers = (limit_size - maximum_size) /
>> THREAD_REGION;
>> + MSG("--num-threads is set to %d.\n",
>> info->num_producers + 1);
>>
>> - limit_size = limit_size - THREAD_REGION *
>> info->num_threads;
>> + limit_size = limit_size - THREAD_REGION *
>> info->num_producers;
>> }
>> }
>>
>> @@ -11103,7 +11103,7 @@ main(int argc, char *argv[])
>> info->working_dir = optarg;
>> break;
>> case OPT_NUM_THREADS:
>> - info->num_threads = MAX(atoi(optarg), 0);
>> + info->num_producers = MAX(atoi(optarg), 1) - 1;
>> break;
>> case '?':
>> MSG("Commandline parameter is invalid.\n");
>> diff --git a/makedumpfile.h b/makedumpfile.h
>> index 533e5b8..6a0f51e 100644
>> --- a/makedumpfile.h
>> +++ b/makedumpfile.h
>> @@ -1004,7 +1004,7 @@ struct page_data
>> };
>>
>> struct thread_args {
>> - int thread_num;
>> + int producer_num;
>> unsigned long len_buf_out;
>> struct cycle *cycle;
>> struct page_data *page_data_buf;
>> @@ -1294,7 +1294,7 @@ struct DumpInfo {
>> /*
>> * for parallel process
>> */
>> - int num_threads;
>> + int num_producers;
>> int num_buffers;
>> pthread_t **threads;
>> struct thread_args *kdump_thread_args;
>> --
>> 1.8.3.1
>>
>>
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