Hello,
> -----Original Message-----
> From: kexec [mailto:[email protected]] On Behalf Of Minoru
> Usui
> Sent: Thursday, February 04, 2016 8:52 AM
> To: Zhou Wenjian <[email protected]>; [email protected]
> 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:[email protected]] On Behalf Of Zhou
> > Wenjian
> > Sent: Monday, February 01, 2016 3:22 PM
> > To: [email protected]
> > 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 <[email protected]>
> > ---
> > 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)
> ===
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:
===
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.
>
> > 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
> > [email protected]
> > http://lists.infradead.org/mailman/listinfo/kexec
>
> _______________________________________________
> kexec mailing list
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