Hi Tony, On Fri, Jul 25, 2025 at 4:21 AM Tony Nguyen <[email protected]> wrote: > > > > On 7/20/2025 2:11 AM, Jason Xing wrote: > > From: Jason Xing <[email protected]> > > > > Resolve the budget underflow which leads to returning true in ixgbe_xmit_zc > > even when the budget of descs are thoroughly consumed. > > > > Before this patch, when the budget is decreased to zero and finishes > > sending the last allowed desc in ixgbe_xmit_zc, it will always turn back > > and enter into the while() statement to see if it should keep processing > > packets, but in the meantime it unexpectedly decreases the value again to > > 'unsigned int (0--)', namely, UINT_MAX. Finally, the ixgbe_xmit_zc returns > > true, showing 'we complete cleaning the budget'. That also means > > 'clean_complete = true' in ixgbe_poll. > > > > The true theory behind this is if that budget number of descs are consumed, > > it implies that we might have more descs to be done. So we should return > > false in ixgbe_xmit_zc to tell napi poll to find another chance to start > > polling to handle the rest of descs. On the contrary, returning true here > > means job done and we know we finish all the possible descs this time and > > we don't intend to start a new napi poll. > > > > It is apparently against our expectations. Please also see how > > ixgbe_clean_tx_irq() handles the problem: it uses do..while() statement > > to make sure the budget can be decreased to zero at most and the underflow > > never happens. > > > > Fixes: 8221c5eba8c1 ("ixgbe: add AF_XDP zero-copy Tx support") > > Hi Jason, > > Seems like this one should be split off and go to iwl-net/net like the > other similar ones [1]? Also, some of the updates made to the other > series apply here as well?
The other three patches are built on top of this one. If without the patch, the whole series will be warned because of build failure. I was thinking we could backport this patch that will be backported to the net branch after the whole series goes into the net-next branch. Or you expect me to cook four patches without this one first so that you could easily cherry pick this one then without building conflict? > > Thanks, > Tony > > [1] > https://lore.kernel.org/netdev/[email protected]/ Regarding this one, should I send a v4 version with the current patch included? And target [iwl-net/net] explicitly as well? I'm not sure if I follow you. Could you instruct me on how to proceed next in detail? Thanks, Jason
