linux-stable.git/net/core/net-sysfs.c, branch linux-5.9.y

net: accept an empty mask in /sys/class/net//queues/rx-/rps_cpus

2020-08-12T20:18:16+00:00

We must accept an empty mask in store_rps_map(), or we are not able
to disable RPS on a queue.

Fixes: 07bbecb34106 ("net: Restrict receive packets queuing to housekeeping CPUs")
Signed-off-by: Eric Dumazet 
Reported-by: Maciej Żenczykowski 
Cc: Alex Belits 
Cc: Nitesh Narayan Lal 
Cc: Peter Zijlstra (Intel) 
Reviewed-by: Maciej Żenczykowski 
Acked-by: Peter Zijlstra (Intel) 
Acked-by: Nitesh Narayan Lal 
Signed-off-by: David S. Miller

Merge tag 'sched-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-08-03T21:58:38+00:00

Pull scheduler updates from Ingo Molnar:

 - Improve uclamp performance by using a static key for the fast path

 - Add the "sched_util_clamp_min_rt_default" sysctl, to optimize for
   better power efficiency of RT tasks on battery powered devices.
   (The default is to maximize performance & reduce RT latencies.)

 - Improve utime and stime tracking accuracy, which had a fixed boundary
   of error, which created larger and larger relative errors as the
   values become larger. This is now replaced with more precise
   arithmetics, using the new mul_u64_u64_div_u64() helper in math64.h.

 - Improve the deadline scheduler, such as making it capacity aware

 - Improve frequency-invariant scheduling

 - Misc cleanups in energy/power aware scheduling

 - Add sched_update_nr_running tracepoint to track changes to nr_running

 - Documentation additions and updates

 - Misc cleanups and smaller fixes

* tag 'sched-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (54 commits)
  sched/doc: Factorize bits between sched-energy.rst & sched-capacity.rst
  sched/doc: Document capacity aware scheduling
  sched: Document arch_scale_*_capacity()
  arm, arm64: Fix selection of CONFIG_SCHED_THERMAL_PRESSURE
  Documentation/sysctl: Document uclamp sysctl knobs
  sched/uclamp: Add a new sysctl to control RT default boost value
  sched/uclamp: Fix a deadlock when enabling uclamp static key
  sched: Remove duplicated tick_nohz_full_enabled() check
  sched: Fix a typo in a comment
  sched/uclamp: Remove unnecessary mutex_init()
  arm, arm64: Select CONFIG_SCHED_THERMAL_PRESSURE
  sched: Cleanup SCHED_THERMAL_PRESSURE kconfig entry
  arch_topology, sched/core: Cleanup thermal pressure definition
  trace/events/sched.h: fix duplicated word
  linux/sched/mm.h: drop duplicated words in comments
  smp: Fix a potential usage of stale nr_cpus
  sched/fair: update_pick_idlest() Select group with lowest group_util when idle_cpus are equal
  sched: nohz: stop passing around unused "ticks" parameter.
  sched: Better document ttwu()
  sched: Add a tracepoint to track rq->nr_running
  ...

net-sysfs: add a newline when printing 'tx_timeout' by sysfs

2020-07-21T22:35:58+00:00

When I cat 'tx_timeout' by sysfs, it displays as follows. It's better to
add a newline for easy reading.

root@syzkaller:~# cat /sys/devices/virtual/net/lo/queues/tx-0/tx_timeout
0root@syzkaller:~#

Signed-off-by: Xiongfeng Wang 
Signed-off-by: David S. Miller

net: Restrict receive packets queuing to housekeeping CPUs

2020-07-08T09:39:02+00:00

With the existing implementation of store_rps_map(), packets are queued
in the receive path on the backlog queues of other CPUs irrespective of
whether they are isolated or not. This could add a latency overhead to
any RT workload that is running on the same CPU.

Ensure that store_rps_map() only uses available housekeeping CPUs for
storing the rps_map.

Signed-off-by: Alex Belits 
Signed-off-by: Nitesh Narayan Lal 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20200625223443.2684-4-nitesh@redhat.com

net: core: recursively find netdev by device node

2020-05-15T17:18:49+00:00

The assumption that a device node is associated either with the
netdev's device, or the parent of that device, does not hold for all
drivers. E.g. Freescale's DPAA has two layers of platform devices
above the netdev. Instead, recursively walk up the tree from the
netdev, allowing any parent to match against the sought after node.

Signed-off-by: Tobias Waldekranz 
Reviewed-by: Florian Fainelli 
Signed-off-by: David S. Miller

net: napi: use READ_ONCE()/WRITE_ONCE()

2020-04-23T19:43:20+00:00

gro_flush_timeout and napi_defer_hard_irqs can be read
from napi_complete_done() while other cpus write the value,
whithout explicit synchronization.

Use READ_ONCE()/WRITE_ONCE() to annotate the races.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

net: napi: add hard irqs deferral feature

2020-04-23T19:43:20+00:00

Back in commit 3b47d30396ba ("net: gro: add a per device gro flush timer")
we added the ability to arm one high resolution timer, that we used
to keep not-complete packets in GRO engine a bit longer, hoping that further
frames might be added to them.

Since then, we added the napi_complete_done() interface, and commit
364b6055738b ("net: busy-poll: return busypolling status to drivers")
allowed drivers to avoid re-arming NIC interrupts if we made a promise
that their NAPI poll() handler would be called in the near future.

This infrastructure can be leveraged, thanks to a new device parameter,
which allows to arm the napi hrtimer, instead of re-arming the device
hard IRQ.

We have noticed that on some servers with 32 RX queues or more, the chit-chat
between the NIC and the host caused by IRQ delivery and re-arming could hurt
throughput by ~20% on 100Gbit NIC.

In contrast, hrtimers are using local (percpu) resources and might have lower
cost.

The new tunable, named napi_defer_hard_irqs, is placed in the same hierarchy
than gro_flush_timeout (/sys/class/net/ethX/)

By default, both gro_flush_timeout and napi_defer_hard_irqs are zero.

This patch does not change the prior behavior of gro_flush_timeout
if used alone : NIC hard irqs should be rearmed as before.

One concrete usage can be :

echo 20000 >/sys/class/net/eth1/gro_flush_timeout
echo 10 >/sys/class/net/eth1/napi_defer_hard_irqs

If at least one packet is retired, then we will reset napi counter
to 10 (napi_defer_hard_irqs), ensuring at least 10 periodic scans
of the queue.

On busy queues, this should avoid NIC hard IRQ, while before this patch IRQ
avoidance was only possible if napi->poll() was exhausting its budget
and not call napi_complete_done().

This feature also can be used to work around some non-optimal NIC irq
coalescing strategies.

Having the ability to insert XX usec delays between each napi->poll()
can increase cache efficiency, since we increase batch sizes.

It also keeps serving cpus not idle too long, reducing tail latencies.

Co-developed-by: Luigi Rizzo 
Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

net: Add testing sysfs attribute

2020-04-20T19:43:24+00:00

Similar to speed, duplex and dorment, report the testing status
in sysfs.

Signed-off-by: Andrew Lunn 
Reviewed-by: Florian Fainelli 
Signed-off-by: David S. Miller

net-sysfs: remove redundant assignment to variable ret

2020-04-09T17:14:53+00:00

The variable ret is being initialized with a value that is never read
and it is being updated later with a new value.  The initialization is
redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King 
Signed-off-by: David S. Miller

net-sysfs: add queue_change_owner()

2020-02-27T04:07:26+00:00

Add a function to change the owner of the queue entries for a network device
when it is moved between network namespaces.

Currently, when moving network devices between network namespaces the
ownership of the corresponding queue sysfs entries are not changed. This leads
to problems when tools try to operate on the corresponding sysfs files. Fix
this.

Signed-off-by: Christian Brauner 
Signed-off-by: David S. Miller