On Fri, Jun 7, 2024 at 8:37 PM Dan Jurgens <danielj@xxxxxxxxxx> wrote: > > > From: Jason Xing <kerneljasonxing@xxxxxxxxx> > > Sent: Friday, June 7, 2024 4:16 AM > > To: Dan Jurgens <danielj@xxxxxxxxxx> > > Cc: Jakub Kicinski <kuba@xxxxxxxxxx>; Michael S. Tsirkin <mst@xxxxxxxxxx>; > > netdev@xxxxxxxxxxxxxxx; jasowang@xxxxxxxxxx; > > xuanzhuo@xxxxxxxxxxxxxxxxx; virtualization@xxxxxxxxxxxxxxx; > > davem@xxxxxxxxxxxxx; edumazet@xxxxxxxxxx; abeni@xxxxxxxxxx; Parav > > Pandit <parav@xxxxxxxxxx> > > Subject: Re: [PATCH net-next] virtio_net: Add TX stop and wake counters > > > > On Sat, Feb 3, 2024 at 12:46 AM Daniel Jurgens <danielj@xxxxxxxxxx> wrote: > > > > > > > From: Jakub Kicinski <kuba@xxxxxxxxxx> > > > > Sent: Friday, February 2, 2024 10:01 AM > > > > Subject: Re: [PATCH net-next] virtio_net: Add TX stop and wake > > > > counters > > > > > > > > On Fri, 2 Feb 2024 14:52:59 +0800 Jason Xing wrote: > > > > > > Can you say more? I'm curious what's your use case. > > > > > > > > > > I'm not working at Nvidia, so my point of view may differ from theirs. > > > > > From what I can tell is that those two counters help me narrow > > > > > down the range if I have to diagnose/debug some issues. > > > > > > > > right, i'm asking to collect useful debugging tricks, nothing > > > > against the patch itself :) > > > > > > > > > 1) I sometimes notice that if some irq is held too long (say, one > > > > > simple case: output of printk printed to the console), those two > > > > > counters can reflect the issue. > > > > > 2) Similarly in virtio net, recently I traced such counters the > > > > > current kernel does not have and it turned out that one of the > > > > > output queues in the backend behaves badly. > > > > > ... > > > > > > > > > > Stop/wake queue counters may not show directly the root cause of > > > > > the issue, but help us 'guess' to some extent. > > > > > > > > I'm surprised you say you can detect stall-related issues with this. > > > > I guess virtio doesn't have BQL support, which makes it special. > > > > Normal HW drivers with BQL almost never stop the queue by themselves. > > > > I mean - if they do, and BQL is active, then the system is probably > > > > misconfigured (queue is too short). This is what we use at Meta to > > > > detect stalls in drivers with BQL: > > > > > > > > https://lore.kernel.org/all/20240131102150.728960-3-leitao@xxxxxxxxx > > > > g/ > > > > > > > > Daniel, I think this may be a good enough excuse to add per-queue > > > > stats to the netdev genl family, if you're up for that. LMK if you > > > > want more info, otherwise I guess ethtool -S is fine for now. > > > > > > For now, I would like to go with ethtool -S. But I can take on the netdev > > level as a background task. Are you suggesting adding them to > > rtnl_link_stats64? > > > > Hello Daniel, Jakub, > > > > Sorry to revive this thread. I wonder why not use this patch like mlnx driver > > does instead of adding statistics into the yaml file? Are we gradually using or > > adding more fields into the yaml file to replace the 'ethtool -S' command? > > > > It's trivial to have the stats in ethtool as well. But I noticed the stats series intentionally removed some stats from ethtool. So I didn't put it both places. Thank you for the reply. I thought there was some particular reason :-)
