> On Jul 21, 2017, at 12:48 PM, Lennart Sorensen <lsore...@csclub.uwaterloo.ca> > wrote: > > On Fri, Jul 21, 2017 at 11:36:27AM -0700, Benjamin Poirier wrote: >> When e1000e_poll() is not fast enough to keep up with incoming traffic, the >> adapter (when operating in msix mode) raises the Other interrupt to signal >> Receiver Overrun. >> >> This is a double problem because 1) at the moment e1000_msix_other() >> assumes that it is only called in case of Link Status Change and 2) if the >> condition persists, the interrupt is repeatedly raised again in quick >> succession. >> >> Ideally we would configure the Other interrupt to not be raised in case of >> receiver overrun but this doesn't seem possible on this adapter. Instead, >> we handle the first part of the problem by reverting to the practice of >> reading ICR in the other interrupt handler, like before commit 16ecba59bc33 >> ("e1000e: Do not read ICR in Other interrupt"). Thanks to commit >> 0a8047ac68e5 ("e1000e: Fix msi-x interrupt automask") which cleared IAME >> from CTRL_EXT, reading ICR doesn't interfere with RxQ0, TxQ0 interrupts >> anymore. We handle the second part of the problem by not re-enabling the >> Other interrupt right away when there is overrun. Instead, we wait until >> traffic subsides, napi polling mode is exited and interrupts are >> re-enabled. >> >> Reported-by: Lennart Sorensen <lsore...@csclub.uwaterloo.ca> >> Fixes: 16ecba59bc33 ("e1000e: Do not read ICR in Other interrupt") >> Signed-off-by: Benjamin Poirier <bpoir...@suse.com> > > Any chance of this fix hitting -stable? After all adapter reset under > load is not nice. >
I tried this patch sequence and I’m seeing a 2% drop in throughput. CPU utilization at softIRQ is also about 8% higher. The previous single patch that went out to fix this problem had better performance. This is on an Atom D525 with an 82574L and running 2 GB streams across a pair of interfaces with iperf3. -Philip