On Wed, Mar 31, 2021 at 04:41:40PM +0200, Phil Sutter wrote:
> On Wed, Mar 31, 2021 at 03:35:10PM +0200, Florian Westphal wrote:
> > Phil Sutter <phil@xxxxxx> wrote:
> > > I'm currently trying to fix for an issue in Kubernetes realm[1]:
> > > Baseline is they are trying to restore a ruleset with ~700k lines and it
> > > fails. Needless to say, legacy iptables handles it just fine.
> > >
> > > Meanwhile I found out there's a limit of 1024 iovecs when submitting the
> > > batch to kernel, and this is what they're hitting.
> > >
> > > I can work around that limit by increasing each iovec (via
> > > BATCH_PAGE_SIZE) but keeping pace with legacy seems ridiculous:
> > >
> > > With a scripted binary-search I checked the maximum working number of
> > > restore items of:
> > >
> > > (1) User-defined chains
> > > (2) rules with merely comment match present
> > > (3) rules matching on saddr, daddr, iniface and outiface
> > >
> > > Here's legacy compared to nft with different factors in BATCH_PAGE_SIZE:
> > >
> > > legacy 32 (stock) 64 128 256
> > > ----------------------------------------------------------------------
> > > 1'636'799 1'602'202 - NC - - NC - - NC -
> > > 1'220'159 302'079 604'160 1'208'320 - NC -
> > > 3'532'040 242'688 485'376 971'776 1'944'576
> >
> > Can you explain that table? What does 1'636'799 mean? NC?
>
> Ah, sorry: NC is "not care", I didn't consider those numbers relevant
> given that iptables-nft has caught up to legacy previously already.
>
> 1'636'799 is the max number of user-defined chains I can successfully
> restore using iptables-legacy-restore. Looks like I dropped the rows'
> description while reformatting by accident: the first row of that table
> corresponds with test (1), second with test (2) and third with test (3).
>
> So legacy may restore at once ~1.6M chains or ~1.2M comment rules or
> ~3.5M rules with {s,d}{addr,iface} matches.
>
> The following columns are for iptables-nft with varying BATCH_PAGE_SIZE
> values. Each of the (max 1024) iovecs passed to kernel via sendmsg() is
> 'N * getpagesize()' large.
Did you measure any slow down in the ruleset load time after selecting
a larger batch chunk size?
