[CRIU] [PATCH] lazy-pages: use intermediate pipe in page_server_get_pages

[Mike Rapoprt]

On June 21, 2017 4:11:56 AM GMT+03:00, Andrei Vagin <avagin at virtuozzo.com> wrote:
>Pavel, could you review this patch.

This one should be discarded. It's superseded by "random page pipe read"

>On Mon, Jun 05, 2017 at 05:52:26PM +0300, Mike Rapoport wrote:
>> Instead of splice()'ing pages directly from the page-pipe into the
>socket,
>> use intermediate pipe and tee(). This way we keep the pages in
>page-pipe
>> and they can be fetched again by the processes that were fork()'ed
>after
>> restore.
>> 
>> Signed-off-by: Mike Rapoport <rppt at linux.vnet.ibm.com>
>> ---
>>  criu/page-xfer.c | 28 ++++++++++++++++------------
>>  1 file changed, 16 insertions(+), 12 deletions(-)
>> 
>> diff --git a/criu/page-xfer.c b/criu/page-xfer.c
>> index c557407..6217d8a 100644
>> --- a/criu/page-xfer.c
>> +++ b/criu/page-xfer.c
>> @@ -705,17 +705,19 @@ static int page_server_get_pages(int sk, struct
>page_server_iov *pi)
>>  	if (!can_send_pages(ppb, iov, pi))
>>  		return -1;
>>  
>> +	ret = tee(ppb->p[0], cxfer.p[1], iov->iov_len, 0);
>> +	if (ret != iov->iov_len)
>> +		return -1;
>> +
>>  	if (send_psi(sk, PS_IOV_ADD, pi->nr_pages, pi->vaddr, pi->dst_id))
>>  		return -1;
>>  
>> -	ret = splice(ppb->p[0], NULL, sk, NULL, iov->iov_len,
>SPLICE_F_MOVE);
>> +	ret = splice(cxfer.p[0], NULL, sk, NULL, iov->iov_len,
>SPLICE_F_MOVE);
>>  	if (ret != iov->iov_len)
>>  		return -1;
>>  
>>  	tcp_nodelay(sk, true);
>>  
>> -	page_pipe_destroy_ppb(ppb);
>> -
>>  	return 0;
>>  }
>>  
>> @@ -724,6 +726,12 @@ static int page_server_serve(int sk)
>>  	int ret = -1;
>>  	bool flushed = false;
>>  
>> +	if (pipe(cxfer.p)) {
>> +		pr_perror("Can't make pipe for xfer");
>> +		close(sk);
>> +		return -1;
>> +	}
>> +
>>  	if (!opts.lazy_pages) {
>>  		/*
>>  		 * This socket only accepts data except one thing -- it
>> @@ -731,19 +739,15 @@ static int page_server_serve(int sk)
>>  		 * make it NODELAY all the time.
>>  		 */
>>  		tcp_nodelay(sk, true);
>> -
>> -		if (pipe(cxfer.p)) {
>> -			pr_perror("Can't make pipe for xfer");
>> -			close(sk);
>> -			return -1;
>> -		}
>> -
>> -		cxfer.pipe_size = fcntl(cxfer.p[0], F_GETPIPE_SZ, 0);
>> -		pr_debug("Created xfer pipe size %u\n", cxfer.pipe_size);
>>  	} else {
>> +		if (fcntl(cxfer.p[0], F_SETPIPE_SZ, PIPE_MAX_SIZE * PAGE_SIZE) <
>0)
>> +			return -1;
>>  		tcp_cork(sk, true);
>>  	}
>>  
>> +	cxfer.pipe_size = fcntl(cxfer.p[0], F_GETPIPE_SZ, 0);
>> +	pr_debug("Created xfer pipe size %u\n", cxfer.pipe_size);
>> +
>>  	while (1) {
>>  		struct page_server_iov pi;
>>  		u32 cmd;
>> -- 
>> 2.7.4
>>