Messages in this thread | | | From | Eric Dumazet <> | Date | Wed, 14 Feb 2024 17:58:37 +0100 | Subject | Re: [PATCH net-next v3] net: dqs: add NIC stall detector based on BQL |
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On Wed, Feb 14, 2024 at 5:49 PM Breno Leitao <leitao@debian.org> wrote: > > On Wed, Feb 14, 2024 at 04:41:36PM +0100, Eric Dumazet wrote: > > On Wed, Feb 14, 2024 at 3:45 PM Breno Leitao <leitao@debian.org> wrote: > > > > > > On Tue, Feb 13, 2024 at 10:04:57AM -0800, Jakub Kicinski wrote: > > > > On Tue, 13 Feb 2024 14:57:49 +0100 Eric Dumazet wrote: > > > > > Please note that adding other sysfs entries is expensive for workloads > > > > > creating/deleting netdev and netns often. > > > > > > > > > > I _think_ we should find a way for not creating > > > > > /sys/class/net/<interface>/queues/tx-{Q}/byte_queue_limits directory > > > > > and files > > > > > for non BQL enabled devices (like loopback !) > > > > > > > > We should try, see if anyone screams. We could use IFF_NO_QUEUE, and > > > > NETIF_F_LLTX as a proxy for "device doesn't have a real queue so BQL > > > > would be pointless"? Obviously better to annotate the drivers which > > > > do have BQL support, but there's >50 of them on a quick count.. > > > > > > Let me make sure I understand the suggestion above. We want to disable > > > BQL completely for devices that has dev->features & NETIF_F_LLTX or > > > dev->priv_flags & IFF_NO_QUEUE, right? > > > > > > Maybe we can add a ->enabled field in struct dql, and set it according > > > to the features above. Then we can created the sysfs and process the dql > > > operations based on that field. This should avoid some unnecessary calls > > > also, if we are not display sysfs. > > > > > > Here is a very simple PoC to represent what I had in mind. Am I in the > > > right direction? > > > > No, this was really about sysfs entries (aka dql_group) > > > > Partial patch would be: > > That is simpler than what I imagined. Thanks! >
> > for netdev_uses_bql(), would it be similar to what I proposed in the > previous message? Let me copy it here. > > static bool netdev_uses_bql(struct net_device *dev) > { > if (dev->features & NETIF_F_LLTX || > dev->priv_flags & IFF_NO_QUEUE) > return false; > > return true; > }
I think this should be fine, yes.
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