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Hello,
On Sun, 14 May 2023, Abhijeet Rastogi wrote:
> Current range [8, 20] is set purely due to historical reasons
> because at the time, ~1M (2^20) was considered sufficient.
> With this change, 27 is the upper limit for 64-bit, 20 otherwise.
>
> Previous change regarding this limit is here.
>
> Link:
> https://lore.kernel.org/all/86eabeb9dd62aebf1e2533926fdd13fed48bab1f.1631289960.git.aclaudi@xxxxxxxxxx/T/#u
>
> Signed-off-by: Abhijeet Rastogi <abhijeet.1989@xxxxxxxxx>
> ---
> The conversation for this started at:
>
> https://www.spinics.net/lists/netfilter/msg60995.html
>
> The upper limit for algo is any bit size less than 32, so this
> change will allow us to set bit size > 20. Today, it is common to have
> RAM available to handle greater than 2^20 connections per-host.
>
> Distros like RHEL already allow setting limits higher than 20.
> ---
> Changes in v2:
> - Lower the ranges, 27 for 64bit, 20 otherwise
> - Link to v1:
> https://lore.kernel.org/r/20230412-increase_ipvs_conn_tab_bits-v1-1-60a4f9f4c8f2@xxxxxxxxx
> ---
> net/netfilter/ipvs/Kconfig | 26 +++++++++++++-------------
> net/netfilter/ipvs/ip_vs_conn.c | 4 ++--
> 2 files changed, 15 insertions(+), 15 deletions(-)
>
> diff --git a/net/netfilter/ipvs/Kconfig b/net/netfilter/ipvs/Kconfig
> index 271da8447b29..aac5d6bd82e6 100644
> --- a/net/netfilter/ipvs/Kconfig
> +++ b/net/netfilter/ipvs/Kconfig
> @@ -44,7 +44,8 @@ config IP_VS_DEBUG
>
> config IP_VS_TAB_BITS
> int "IPVS connection table size (the Nth power of 2)"
> - range 8 20
> + range 8 20 if !64BIT
> + range 8 27 if 64BIT
> default 12
> help
> The IPVS connection hash table uses the chaining scheme to handle
> @@ -52,18 +53,17 @@ config IP_VS_TAB_BITS
> reduce conflicts when there are hundreds of thousands of connections
> in the hash table.
>
> - Note the table size must be power of 2. The table size will be the
> - value of 2 to the your input number power. The number to choose is
> - from 8 to 20, the default number is 12, which means the table size
> - is 4096. Don't input the number too small, otherwise you will lose
> - performance on it. You can adapt the table size yourself, according
> - to your virtual server application. It is good to set the table size
> - not far less than the number of connections per second multiplying
> - average lasting time of connection in the table. For example, your
> - virtual server gets 200 connections per second, the connection lasts
> - for 200 seconds in average in the connection table, the table size
> - should be not far less than 200x200, it is good to set the table
> - size 32768 (2**15).
> + Note the table size must be power of 2. The table size will be the
> value
> + of 2 to the your input number power. The number to choose is from 8
> to 27
> + for 64BIT(20 otherwise), the default number is 12, which means the
> table
> + size is 4096. Don't input the number too small, otherwise you will
> lose
> + performance on it. You can adapt the table size yourself, according to
> + your virtual server application. It is good to set the table size not
> far
> + less than the number of connections per second multiplying average
> lasting
> + time of connection in the table. For example, your virtual server
> gets
> + 200 connections per second, the connection lasts for 200 seconds in
> + average in the connection table, the table size should be not far less
> + than 200x200, it is good to set the table size 32768 (2**15).
Can you keep the previous line width of the above help
because on standard 80-width window the help now gets truncated in
make menuconfig.
After that I'll send a patch on top of yours to limit the
rows depending on the memory.
> Another note that each connection occupies 128 bytes effectively and
> each hash entry uses 8 bytes, so you can estimate how much memory is
> diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
> index 13534e02346c..e1b9b52909a5 100644
> --- a/net/netfilter/ipvs/ip_vs_conn.c
> +++ b/net/netfilter/ipvs/ip_vs_conn.c
> @@ -1484,8 +1484,8 @@ int __init ip_vs_conn_init(void)
> int idx;
>
> /* Compute size and mask */
> - if (ip_vs_conn_tab_bits < 8 || ip_vs_conn_tab_bits > 20) {
> - pr_info("conn_tab_bits not in [8, 20]. Using default value\n");
> + if (ip_vs_conn_tab_bits < 8 || ip_vs_conn_tab_bits > 27) {
> + pr_info("conn_tab_bits not in [8, 27]. Using default value\n");
> ip_vs_conn_tab_bits = CONFIG_IP_VS_TAB_BITS;
> }
> ip_vs_conn_tab_size = 1 << ip_vs_conn_tab_bits;
>
> ---
Regards
--
Julian Anastasov <ja@xxxxxx>
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