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). 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; --- base-commit: 09a9639e56c01c7a00d6c0ca63f4c7c41abe075d change-id: 20230412-increase_ipvs_conn_tab_bits-4322c90da216 Best regards, -- Abhijeet Rastogi <abhijeet.1989@xxxxxxxxx>
