Re: [PATCH v2] ipvs: increase ip_vs_conn_tab_bits range for 64BIT

Hi Julian Anastasov,

>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.

Refer this screenshot: https://i.imgur.com/9LgttpC.png

Sorry for the confusion, I was already expecting this comment. The
patch had a few words added, hence it feels like many lines have
changed. However, no line actually exceeds 80 width.

Longest line is still 80-width max. Do you prefer I reduce it to a
lower number like 70?

Thanks,
Abhijeet


On Mon, May 15, 2023 at 8:18 AM Julian Anastasov <[email protected]> wrote:
>
>
>         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@redhat.com/T/#u
> >
> > Signed-off-by: Abhijeet Rastogi <[email protected]>
> > ---
> > 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/[email protected]
> > ---
> >  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 <[email protected]>
>


--
Cheers,
Abhijeet (https://abhi.host)