Re: [PATCH v2] net: fix functions and variables related to netns_ipvs->sysctl_sync_qlen_max

Julian Anastasov
2013-02-07T08:41:28Z

Hello,

On Thu, 7 Feb 2013, Zhang Yanfei wrote:

> Since the type of netns_ipvs->sysctl_sync_qlen_max has been changed to
> unsigned long, type of its related proc var sync_qlen_max should be changed
> to unsigned long, too. Also the return type of function sysctl_sync_qlen_max().
>
> Besides, the type of ipvs_master_sync_state->sync_queue_len should also be
> changed to unsigned long.

v2 looks fine. Thanks! Regarding your question
see below...

> Changelog from V1:
> - change type of ipvs_master_sync_state->sync_queue_len to unsigned long
> as Simon addressed.
>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: David Miller <davem@davemloft.net>
> Cc: Julian Anastasov <ja@ssi.bg>
> Cc: Simon Horman <horms@verge.net.au>
> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
> ---
> include/net/ip_vs.h | 6 +++---
> net/netfilter/ipvs/ip_vs_ctl.c | 4 ++--
> 2 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
> index 68c69d5..1d56f92 100644
> --- a/include/net/ip_vs.h
> +++ b/include/net/ip_vs.h
> @@ -874,7 +874,7 @@ struct ip_vs_app {
> struct ipvs_master_sync_state {
> struct list_head sync_queue;
> struct ip_vs_sync_buff *sync_buff;
> - int sync_queue_len;
> + unsigned long sync_queue_len;
> unsigned int sync_queue_delay;
> struct task_struct *master_thread;
> struct delayed_work master_wakeup_work;
> @@ -1052,7 +1052,7 @@ static inline int sysctl_sync_ports(struct netns_ipvs *ipvs)
> return ACCESS_ONCE(ipvs->sysctl_sync_ports);
> }
>
> -static inline int sysctl_sync_qlen_max(struct netns_ipvs *ipvs)
> +static inline unsigned long sysctl_sync_qlen_max(struct netns_ipvs *ipvs)
> {
> return ipvs->sysctl_sync_qlen_max;
> }
> @@ -1099,7 +1099,7 @@ static inline int sysctl_sync_ports(struct netns_ipvs *ipvs)
> return 1;
> }
>
> -static inline int sysctl_sync_qlen_max(struct netns_ipvs *ipvs)
> +static inline unsigned long sysctl_sync_qlen_max(struct netns_ipvs *ipvs)
> {
> return IPVS_SYNC_QLEN_MAX;
> }
> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> index ec664cb..d79a530 100644
> --- a/net/netfilter/ipvs/ip_vs_ctl.c
> +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> @@ -1747,9 +1747,9 @@ static struct ctl_table vs_vars[] = {
> },
> {
> .procname = "sync_qlen_max",
> - .maxlen = sizeof(int),
> + .maxlen = sizeof(unsigned long),
> .mode = 0644,
> - .proc_handler = proc_dointvec,
> + .proc_handler = proc_doulongvec_minmax,
> },
> {
> .procname = "sync_sock_size",
> --
> 1.7.1

> Another question about the sysctl_sync_qlen_max:
> This variable is assigned as:
>
> ipvs->sysctl_sync_qlen_max = nr_free_buffer_pages() / 32;
>
> The function nr_free_buffer_pages actually means: counts of pages
> which are beyond high watermark within ZONE_DMA and ZONE_NORMAL.
>
> is it ok to be called here? Some people misused this function because
> the function name was misleading them. I am sorry I am totally not
> familiar with the ipvs code, so I am just asking you about
> this.

Using nr_free_buffer_pages should be fine here.
We are using it as rough estimation for the number of sync
buffers we can use in NORMAL zones. We are using dev->mtu
for such buffers, so it can take a PAGE_SIZE for a buffer.
We are not interested in HIGHMEM size. high watermarks
should have negliable effect. I'm even not sure whether
we need to clamp it for systems with TBs of memory.

Regards

--
Julian Anastasov <ja@ssi.bg>