Hi Dave, I saw that code. Please excuse me if I'm wrong with below issue:
Step #1: vlib_node_runtime_update_stats() receives n_clocks (uword), assume this n_clocks has value bigger than 32 bit can hold. Step #2: We are setting node->max_clock (note that here max_clock already overflowed as n_clocks is big value) Step #3: Now we call vlib_node_runtime_sync_stats() and pass node as argument along with n_clocks. Step #4: In vlib_node_runtime_sync_stats(), we set n->stats_total.max_clock = r->max_clock; from node(32 bit field) which already overflowed. I think we should have the logic like below inside vlib_node_runtime_sync_stats(). n->stats_total.max_clock = n_clocks > n->stats_total.max_clock ? n_clocks : n->stats_total.max_clock; # all variables are 64 bit here Thanks, Nagaraju On Fri, Mar 27, 2020 at 11:11 AM Dave Barach (dbarach) <dbar...@cisco.com> wrote: > vlib_node_runtime_update_stats(...) > > > > *From:* Nagaraju Vemuri <nagarajuiit...@gmail.com> > *Sent:* Friday, March 27, 2020 12:54 PM > *To:* Dave Barach (dbarach) <dbar...@cisco.com> > *Cc:* vpp-dev@lists.fd.io > *Subject:* Re: [vpp-dev] clocks stored in vlib_node_runtime_t #vpp > #counters > > > > Thanks for your reply Dave. > > > > Can you please point me to the code where we copy into 64 bit counters > when 32 bit overflows? > > > > When we issue the command "show runtime max", do we print the data from 64 > bit counters? > > > > I made max_clock variable 64 bit type locally to experiment. > > And found different output from "show runtime max". > > Max clock was 7.49e9 with 64 bit field, whereas it was within 4e9(because > of 32 bit limitation) with 32 bit field. > > > > Regards, > > Nagaraju > > > > On Fri, Mar 27, 2020 at 4:52 AM Dave Barach (dbarach) <dbar...@cisco.com> > wrote: > > We scrape the 32-bit node-runtime counters back into the 64 bit node > counters when they overflow. > > > > It should take a good long time for a 32-bit counter to overflow – O(1 > seconds’ worth of node runtime) – we do this to reduce the cache footprint > of the node-runtime. > > > > HTH... Dave > > > > *From:* vpp-dev@lists.fd.io <vpp-dev@lists.fd.io> *On Behalf Of * > nagarajuiit...@gmail.com > *Sent:* Friday, March 27, 2020 1:59 AM > *To:* vpp-dev@lists.fd.io > *Subject:* [vpp-dev] clocks stored in vlib_node_runtime_t #vpp #counters > > > > Hi, > > I see that clib_cpu_time_now() returns u64 type data. > And we are updating max clocks spent by a node in vlib_node_runtime_t > using these timestamps. > > Why are we using u32 types in vlib_node_runtime_t? > Because of this, it can only hold data within 2 seconds and anything above > 32 bit range overflows in our system. > > Really appreciate your help. > > Thanks, > Nagaraju > > > > > -- > > Thanks, > Nagaraju Vemuri > -- Thanks, Nagaraju Vemuri
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