On Wed, Nov 30, 2016 at 11:00 PM, Eric Dumazet <eric.duma...@gmail.com> wrote: > On Wed, 2016-11-30 at 22:42 +0200, Saeed Mahameed wrote: >> On Wed, Nov 30, 2016 at 7:35 PM, Eric Dumazet <eric.duma...@gmail.com> wrote: >> > On Wed, 2016-11-30 at 18:46 +0200, Saeed Mahameed wrote: >> > >> >> we had/still have the proper stats they are the ones that >> >> mlx4_en_fold_software_stats is trying to cache into (they always >> >> exist), >> >> but the ones that you are trying to read from (the mlx4 rings) are gone ! >> >> >> >> This bug is totally new and as i warned, this is another symptom of >> >> the real root cause (can't sleep while reading stats). >> >> >> >> Eric what do you suggest ? Keep pre-allocated MAX_RINGS stats and >> >> always iterate over all of them to query stats ? >> >> what if you have one ring/none/1K ? how would you know how many to query ? >> > >> > I am suggesting I will fix the bug I introduced. >> > >> > Do not panic. >> > >> > >> >> Not at all, I trust you are the only one who is capable of providing >> the best solution. >> I am just trying to read your mind :-). >> >> As i said i like the solution and i want to adapt it to mlx5, so I am >> a little bit enthusiastic :) > > What about the following fix guys ? > > As a bonus we update the stats right before they are sent to monitors > via rtnetlink ;)
Hi Eric, Thanks for the patch, I already acked it. I have one educational question (not related to this patch, but related to stats reading in general). I was wondering why do we need to disable bh every time we read stats "spin_lock_bh" ? is it essential ? I checked and in mlx4 we don't hold stats_lock in softirq (en_rx.c/en_tx.c), so I don't see any deadlock risk in here.. Thanks Saeed.
