No description
  • C 98.2%
  • Assembly 1%
  • Makefile 0.3%
  • Shell 0.2%
  • Python 0.1%
Find a file
Repository files (latest commit first)
Filename Latest commit message Latest commit date
Ido Schimmel 2f58abe770 nexthop: Fix performance regression in nexthop deletion
[ Upstream commit df6afe2f7c19349de2ee560dc62ea4d9ad3ff889 ]

While insertion of 16k nexthops all using the same netdev ('dummy10')
takes less than a second, deletion takes about 130 seconds:

# time -p ip -b nexthop.batch
real 0.29
user 0.01
sys 0.15

# time -p ip link set dev dummy10 down
real 131.03
user 0.06
sys 0.52

This is because of repeated calls to synchronize_rcu() whenever a
nexthop is removed from a nexthop group:

# /usr/share/bcc/tools/offcputime -p `pgrep -nx ip` -K
...
    b'finish_task_switch'
    b'schedule'
    b'schedule_timeout'
    b'wait_for_completion'
    b'__wait_rcu_gp'
    b'synchronize_rcu.part.0'
    b'synchronize_rcu'
    b'__remove_nexthop'
    b'remove_nexthop'
    b'nexthop_flush_dev'
    b'nh_netdev_event'
    b'raw_notifier_call_chain'
    b'call_netdevice_notifiers_info'
    b'__dev_notify_flags'
    b'dev_change_flags'
    b'do_setlink'
    b'__rtnl_newlink'
    b'rtnl_newlink'
    b'rtnetlink_rcv_msg'
    b'netlink_rcv_skb'
    b'rtnetlink_rcv'
    b'netlink_unicast'
    b'netlink_sendmsg'
    b'____sys_sendmsg'
    b'___sys_sendmsg'
    b'__sys_sendmsg'
    b'__x64_sys_sendmsg'
    b'do_syscall_64'
    b'entry_SYSCALL_64_after_hwframe'
    -                ip (277)
        126554955

Since nexthops are always deleted under RTNL, synchronize_net() can be
used instead. It will call synchronize_rcu_expedited() which only blocks
for several microseconds as opposed to multiple milliseconds like
synchronize_rcu().

With this patch deletion of 16k nexthops takes less than a second:

# time -p ip link set dev dummy10 down
real 0.12
user 0.00
sys 0.04

Tested with fib_nexthops.sh which includes torture tests that prompted
the initial change:

# ./fib_nexthops.sh
...
Tests passed: 134
Tests failed:   0

Fixes: 90f33bffa382 ("nexthops: don't modify published nexthop groups")
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Link: https://lore.kernel.org/r/20201016172914.643282-1-idosch@idosch.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-29 09:57:26 +01:00
arch ARM: 8939/1: kbuild: use correct nm executable 2020-10-17 10:11:22 +02:00
block block/diskstats: more accurate approximation of io_ticks for slow disks 2020-10-07 08:01:29 +02:00
certs
crypto crypto: af_alg - Work around empty control messages without MSG_MORE 2020-09-03 11:27:05 +02:00
Documentation block/diskstats: more accurate approximation of io_ticks for slow disks 2020-10-07 08:01:29 +02:00
drivers net: hdlc_raw_eth: Clear the IFF_TX_SKB_SHARING flag after calling ether_setup 2020-10-29 09:57:26 +01:00
fs reiserfs: Fix oops during mount 2020-10-17 10:11:23 +02:00
include ALSA: hda: fix jack detection with Realtek codecs when in D3 2020-10-29 09:57:25 +01:00
init kprobes: tracing/kprobes: Fix to kill kprobes on initmem after boot 2020-10-01 13:18:23 +02:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel perf: Fix task_function_call() error handling 2020-10-14 10:33:05 +02:00
lib Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts 2020-10-14 10:32:56 +02:00
LICENSES
mm mm: khugepaged: recalculate min_free_kbytes after memory hotplug as expected by khugepaged 2020-10-14 10:33:05 +02:00
net nexthop: Fix performance regression in nexthop deletion 2020-10-29 09:57:26 +01:00
samples bpf: Fix fds_example SIGSEGV error 2020-08-19 08:16:03 +02:00
scripts scripts/dtc: only append to HOST_EXTRACFLAGS instead of overwriting 2020-10-07 08:01:29 +02:00
security device_cgroup: Fix RCU list debugging warning 2020-10-01 13:18:13 +02:00
sound ALSA: hda/hdmi: fix incorrect locking in hdmi_pcm_close 2020-10-29 09:57:25 +01:00
tools perf cs-etm: Move definition of 'traceid_list' global variable from header file 2020-10-17 10:11:21 +02:00
usr
virt KVM: arm64: Assume write fault on S1PTW permission fault on instruction fetch 2020-10-01 13:18:25 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Documentation/llvm: add documentation on building w/ Clang/LLVM 2020-08-26 10:40:46 +02:00
Makefile Linux 5.4.72 2020-10-17 10:11:24 +02:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.