When running workloads heavy unbalanced towards TX (high TX, low RX
traffic), sfc driver can retain the CPU during too long times. Although
in many cases this is not enough to be visible, it can affect
performance and system responsiveness.
A way to reproduce it is to use a debug kernel and run some parallel
netperf TX tests. In some systems, this will lead to this message being
logged:
kernel:watchdog: BUG: soft lockup - CPU#12 stuck for 22s!
The reason is that sfc driver doesn't account any NAPI budget for the TX
completion events work. With high-TX/low-RX traffic, this makes that the
CPU is held for long time for NAPI poll.
Documentations says "drivers can process completions for any number of Tx
packets but should only process up to budget number of Rx packets".
However, many drivers do limit the amount of TX completions that they
process in a single NAPI poll.
In the same way, this patch adds a limit for the TX work in sfc. With
the patch applied, the watchdog warning never appears.
Tested with netperf in different combinations: single process / parallel
processes, TCP / UDP and different sizes of UDP messages. Repeated the
tests before and after the patch, without any noticeable difference in
network or CPU performance.
Test hardware:
Intel(R) Xeon(R) CPU E5-1620 v4 @ 3.50GHz (4 cores, 2 threads/core)
Solarflare Communications XtremeScale X2522-25G Network Adapter
Fixes: 5227ecccea ("sfc: remove tx and MCDI handling from NAPI budget consideration")
Fixes: d19a537218 ("sfc_ef100: TX path for EF100 NICs")
Reported-by: Fei Liu <feliu@redhat.com>
Signed-off-by: Íñigo Huguet <ihuguet@redhat.com>
Acked-by: Martin Habets <habetsm.xilinx@gmail.com>
Link: https://lore.kernel.org/r/20230615084929.10506-1-ihuguet@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
A non-null efv in __ef100_enqueue_skb() indicates that the packet is
from that representor, should be transmitted with a suitable option
descriptor (to instruct the switch to deliver it to the representee),
and should not be accounted to the parent PF's stats or BQL.
Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
No TX or RX path, no MCDI, not even an ifup/down handler.
Besides stubs, the bulk of the patch deals with reading the Xilinx
extended PCIe capability, which tells us where to find our BAR.
Though in the same module, EF100 has its own struct pci_driver,
which is named sfc_ef100.
A small number of additional nic_type methods are added; those in the
TX (tx_enqueue) and RX (rx_packet) paths are called through indirect
call wrappers to minimise the performance impact.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ef100 will need to check this against NIC limits.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ef100 will need this if it gets GSO skbs it can't handle (e.g. too long
header length).
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
We now ignore the "completion" event when using tx queue timestamping,
and only pay attention to the two (high and low) timestamp events. The
NIC will send a pair of timestamp events for every packet transmitted.
The current firmware may merge the completion events, and it is possible
that future versions may reorder the completion and timestamp events.
As such the completion event is not useful.
Without this patch in place a merged completion event on a queue with
timestamping will cause a "spurious TX completion" error. This affects
SFN8000-series adapters.
Signed-off-by: Tom Zhao <tzhao@solarflare.com>
Acked-by: Martin Habets <mhabets@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The code that handles transmission finalization will also be common.
Signed-off-by: Alexandru-Mihai Maftei <amaftei@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
New headers contain prototypes of functions that will be common between
ef10 and upcoming driver.
Removed static modifier from the affected functions.
Some function prototypes were removed from existing headers.
Signed-off-by: Alexandru-Mihai Maftei <amaftei@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
