[CRIU] [PATCH] ns: Dump namespaces in parallel

[Andrew Vagin]

Acked-by: Andrew Vagin <avagin at parallels.com>
On Mon, Sep 22, 2014 at 04:28:52PM +0400, Pavel wrote:
> The main reason for this is -- dumping namespace has a lot of
> points when the process just waits for something. At the same
> time criu process wait for the ns dumper and doesn't dump
> others.
> 
> The great example of waiting for something is setns syscall.
> Very often it calls synchronize_rcu() which can be quite long.
> Let other processes do smth useful while this.
> 
> Signed-off-by: Pavel Emelyanov <xemul at parallels.com>
> ---
>  namespaces.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/namespaces.c b/namespaces.c
> index e73760c..d15f1ba 100644
> --- a/namespaces.c
> +++ b/namespaces.c
> @@ -459,7 +459,7 @@ int dump_namespaces(struct pstree_item *item, unsigned int ns_flags)
>  {
>  	struct pid *ns_pid = &item->pid;
>  	struct ns_id *ns;
> -	int pid, status;
> +	int pid, nr = 0;
>  	int ret = 0;
>  
>  	/*
> @@ -504,8 +504,14 @@ int dump_namespaces(struct pstree_item *item, unsigned int ns_flags)
>  			exit(ret);
>  		}
>  
> -		ret = waitpid(pid, &status, 0);
> -		if (ret != pid) {
> +		nr++;
> +	}
> +
> +	while (nr > 0) {
> +		int status;
> +
> +		ret = waitpid(-1, &status, 0);
> +		if (ret < 0) {
>  			pr_perror("Can't wait ns dumper");
>  			return -1;
>  		}
> @@ -514,6 +520,8 @@ int dump_namespaces(struct pstree_item *item, unsigned int ns_flags)
>  			pr_err("Namespaces dumping finished with error %d\n", status);
>  			return -1;
>  		}
> +
> +		nr--;
>  	}
>  
>  	pr_info("Namespaces dump complete\n");
> -- 
> 1.8.4.2
> 
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