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:[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().
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
[email protected]
http://lists.infradead.org/mailman/listinfo/kexec
_______________________________________________
kexec mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/kexec
_______________________________________________
kexec mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/kexec
