Messages in this thread |  | | Date | Tue, 2 Sep 2025 16:53:02 +0800 (CST) | | From | "Lange Tang" <> | | Subject | Re:Re: [PATCH] net: remove local_bh_enable during busy poll |
| |
Thanks for your reply!
I've done some testing, pps=350000,net.core.busy_read=50.
Before apply this patch: unhandled ≈ 6400/s After apply this patch: unhandled < 10/s
As you said, the driver needs to discern spurious interrupts in above describing situation, which I strongly agree with. and I also think that it's necessary to remove local_bh_enable during busy polling, as it causes interrupts to be enabled during the busy poll.
I think fix this issue requires two patches, in addition to this patch, another patch is needed from the driver side to discern spurious interrupts.
At 2025-09-02 04:23:30, "Jakub Kicinski" <kuba@kernel.org> wrote: >On Fri, 29 Aug 2025 11:04:56 +0800 Longjun Tang wrote: >> When CONFIG_NET_RX_BUSY_POLL==Y and net.core.busy_read > 0, >> the __napi_busy_loop function calls napi_poll to perform busy polling, >> such as in the case of virtio_net's virnet_poll. If interrupts are enabled >> during the busy polling process, it is possible that data has already been >> received and that last_used_idx is updated before the interrupt is handled. >> This can lead to the vring_interrupt returning IRQ_NONE in response to the >> interrupt because used_idx == last_used_idx, which is considered a spurious >> interrupt.Once certain conditions are met, this interrupt can be disabled. > >I'm not sure this patch completely fixes the issue you're describing. >It just makes it less likely to happen. Really, it feels like the onus >for fixing this is on the driver that can't discern its own IRQ sources. >-- >pw-bot: cr
|  |