On 02/15/2016 10:15 AM, "Zhou, Wenjian/周文剑" wrote:
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.
Sorry, it seems I was wrong.
It can't work well in cyclic mode.
I will fix it in the next version.
--
Thanks
Zhou
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