[PATCH v2] Improve the performance of --num-threads -d 31

"Zhou, Wenjian/周文?" zhouwj-fnst at cn.fujitsu.com
Tue Feb 23 00:29:51 PST 2016


Hi

On 02/23/2016 04:00 PM, Minoru Usui wrote:
>   Hi,
> 
>> -----Original Message-----
>> From: "Zhou, Wenjian/周文?" [mailto:zhouwj-fnst at cn.fujitsu.com]
>> Sent: Tuesday, February 23, 2016 12:45 PM
>> To: Usui Minoru(碓井 成) <min-usui at ti.jp.nec.com>; kexec at lists.infradead.org
>> Subject: Re: [PATCH v2] Improve the performance of --num-threads -d 31
>>
>> Hello Usui,
>>
>> On 02/23/2016 09:32 AM, Minoru Usui wrote:
>>> Hello, Zhou
>>>
>>> Thank you for reflecting my comments.
>>> I have other comments.
>>>
>>> See below.
>>>
>>>> -----Original Message-----
>>>> From: kexec [mailto:kexec-bounces at lists.infradead.org] On Behalf Of Zhou Wenjian
>>>> Sent: Wednesday, February 17, 2016 4:06 PM
>>>> To: kexec at lists.infradead.org
>>>> Subject: [PATCH v2] Improve the performance of --num-threads -d 31
>>>>
>>>> v2:
>>>>           1. address Minoru Usui's comments about magic number and error message
>>>>           2. fix a bug in cyclic mode caused by optimizing
>>>>
>>>> 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 <zhouwj-fnst at cn.fujitsu.com>
>>>> ---
>>>>    makedumpfile.c | 266 ++++++++++++++++++++++++++++++++++++++-------------------
>>>>    makedumpfile.h |  31 ++++---
>>>>    2 files changed, 200 insertions(+), 97 deletions(-)
>>>>
>>>> diff --git a/makedumpfile.c b/makedumpfile.c
>>>> index fa0b779..31329b5 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] = 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 +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;
>>>> +	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 +7172,46 @@ 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 (pfn < kdump_thread_args->end_pfn) {
>>>> +		buf_ready = FALSE;
>>>>
>>>> -		if (pfn >= kdump_thread_args->end_pfn)
>>>> -			break;
>>>> +		while (page_data_buf[index].used != FALSE ||
>>>> +				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 = TRUE;
>>>>
>>>>    		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 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);
>>>>
>>>> -			buf_ready = TRUE;
>>>> +			page_flag_buf->pfn = pfn;
>>>>
>>>> -			page_data_buf[index].pfn = pfn;
>>>> -			page_data_buf[index].ready = 1;
>>>> +			if (pfn >= kdump_thread_args->end_pfn) {
>>>> +				page_data_buf[index].used = FALSE;
>>>> +				page_flag_buf->ready = FLAG_READY;
>>>> +				break;
>>>> +			}
>>>>
>>>>    			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 +7224,11 @@ 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.
>>>> @@ -7232,12 +7278,16 @@ 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 +7315,15 @@ 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 +7370,11 @@ 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 = FALSE;
>>>>    		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 +7388,9 @@ 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 +7403,101 @@ 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) {
>>>> +					/*
>>>> +					 * prevent setting FLAG_UNUSED being optimized.
>>>> +					 */
>>>> +					MSG("-");
>>>
>>> Why does this line need?
>>> Please clarify why FLAG_UNUSED is optimized.
>>>
>>
>> I tried but still can't figure out the reason or get better solution.
>> I will be so happy if you can help me.
>>
>> In gdb, I run it by step.
>> The code "info->page_flag_buf[i]->ready = FLAG_UNUSED;" can never be reached.
>> If a breakpoint is set here, the code will never be skipped.
> 
> On my environment, RHEL7.2, gdb stops at this line even if MSG("-") is deleted.
> See below.
> 
> ===
> [root at ark crash]# gdb makedumpfile-code-3d32567394bac85ee3247780bfa41072b0d9bfe9/makedumpfile
> GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-80.el7
> Copyright (C) 2013 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
> and "show warranty" for details.
> This GDB was configured as "x86_64-redhat-linux-gnu".
> For bug reporting instructions, please see:
> <http://www.gnu.org/software/gdb/bugs/>...
> Reading symbols from /work/crash/makedumpfile-code-3d32567394bac85ee3247780bfa41072b0d9bfe9/makedumpfile...done.
> (gdb) set args -l -d0 --num-threads=2 ./vmcore ./vmcore.new.2
> (gdb) l 7780
> 7775                                    if (info->page_flag_buf[i]->ready == FLAG_UNUSED)
> 7776                                            continue;
> 7777                                    temp_pfn = info->page_flag_buf[i]->pfn;
> 7778
> 7779                                    /*
> 7780                                     * count how many threads have reached the end.
> 7781                                     */
> 7782                                    if (temp_pfn >= end_pfn) {
> 7783                                            info->page_flag_buf[i]->ready = FLAG_UNUSED;
> 7784
> (gdb) b 7783
> Breakpoint 1 at 0x433778: file makedumpfile.c, line 7783.
> (gdb)
> (gdb) run
> Starting program: /work/crash/makedumpfile-code-3d32567394bac85ee3247780bfa41072b0d9bfe9/makedumpfile -l -d0 --num-threads=2 ./vmcore ./vmcore.new.2
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib64/libthread_db.so.1".
> The kernel version is not supported.
> The makedumpfile operation may be incomplete.
> Checking for memory holes          : [100.0 %] |[New Thread 0x7ffff6530700 (LWP 32123)]
> [New Thread 0x7ffff5d2f700 (LWP 32124)]
> Copying data                       : [ 98.8 %] |
> Breakpoint 1, write_kdump_pages_parallel_cyclic (cd_header=<optimized out>,
>      cd_page=<optimized out>, pd_zero=<optimized out>, offset_data=<optimized out>,
>      cycle=<optimized out>) at makedumpfile.c:7783
> 7783                                            info->page_flag_buf[i]->ready = FLAG_UNUSED;
> Missing separate debuginfos, use: debuginfo-install bzip2-libs-1.0.6-13.el7.x86_64 elfutils-libelf-0.163-3.el7.x86_64 elfutils-libs-0.163-3.el7.x86_64 glibc-2.17-105.el7.x86_64 lzo-2.06-8.el7.x86_64 xz-libs-5.1.2-12alpha.el7.x86_64 zlib-1.2.7-15.el7.x86_64
> (gdb) bt
> #0  write_kdump_pages_parallel_cyclic (cd_header=<optimized out>, cd_page=<optimized out>,
>      pd_zero=<optimized out>, offset_data=<optimized out>, cycle=<optimized out>)
>      at makedumpfile.c:7783
> #1  0x0000000000439a15 in write_kdump_pages_and_bitmap_cyclic (
>      cd_header=cd_header at entry=0x7fffffffe2d0, cd_page=cd_page at entry=0x7fffffffe300)
>      at makedumpfile.c:8501
> #2  0x000000000043a918 in writeout_dumpfile () at makedumpfile.c:9497
> #3  0x000000000044181c in create_dumpfile () at makedumpfile.c:9724
> #4  0x00000000004086df in main (argc=<optimized out>, argv=0x7fffffffe468)
>      at makedumpfile.c:11159
> (gdb)
> ===
> 

Yes, it won't be skipped every time without MSG("-").
But it did occur sometime.
And unluckily, MSG("-") can't do much help either.

I guess it is the same problem that minfei meets.

I'm doing some further investigation.

>>>>
>>>> -		/*
>>>> -		 * check pfn first without mutex locked to reduce the time
>>>> -		 * trying to lock the mutex
>>>> -		 */
>>>> -		if (page_data_buf[index].pfn != consuming_pfn)
>>>> -			continue;
>>>> +					info->page_flag_buf[i]->ready = FLAG_UNUSED;
>>>>
>>>> -		if (pthread_mutex_trylock(&page_data_buf[index].mutex) != 0)
>>>> -			continue;
>>>> +					info->current_pfn = end_pfn;
>>>
>>> This part doesn't get info->current_pfn_mutex.
>>> It becomes bigger than end_pfn at the end of producer thread in following case.
>>>
>>> ===
>>>     producer                   Consumer
>>> ---------------------------------------------------------
>>>     pthread_mutex_lock()
>>>     pfn = info->current_pfn
>>>                                info->current_pfn = end_pfn
>>>     info->current_pfn++
>>>       -> end_pfn + 1
>>>     pthread_mutex_unlock()
>>> ===
>>>
>>> But I know, if this race is happened, processing other producer thread and consumer thread works well
>>> in current cycle.
>>> Because each thread checks whether info->current_pfn >= end_pfn.
>>>
>>> On the other hand, info->current_pfn is initialized to cycle->start_pfn before pthread_create()
>>> in write_kdump_pages_parallel_cyclic().
>>> This means it does not cause a problem in next cycle, too.
>>>
>>> In other words, my point is following.
>>>
>>>     a) When info->current_pfn changes, you have to get info->current_pfn_mutex.
>>>     b) If you allow info->current_pfn is bigger than end_pfn at the end of each cycle,
>>>        "info->current_pfn = end_pfn;" is unnecessary.
>>>
>>> Honestly, I don't like approach b).
>>
>> You're right. Some thing I thought is wrong.
>> But I don't like lock if I have other choice.
>> I will set info->current_pfn before returning.
>> How about it?
> 
> If you mean you set info->current_pfn by producer side,
> this race will occur between producer A and producer B.
> 
> I think you can't avoid getting mutex lock, if you will change info->current_pfn.
> 

I mean setting it by consumer.

-- 
Thanks
Zhou

> Thanks,
> Minoru Usui
> 
> 
>> --
>> Thanks
>> Zhou
>>
>>>
>>> Thanks,
>>> Minoru Usui
>>>
>>>> +					end_count++;
>>>> +					continue;
>>>> +				}
>>>> +
>>>> +				if (current_pfn < temp_pfn)
>>>> +					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;
>>>> +				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;
>>>> +			}
>>>> +
>>>> +			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 +7513,12 @@ 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 %]
>>>> @@ -7464,7 +7557,7 @@ 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 +7657,7 @@ 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
>>>> kexec at lists.infradead.org
>>>> http://lists.infradead.org/mailman/listinfo/kexec
>>
>>
> 
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