diff options
author | Ingo Molnar <mingo@kernel.org> | 2014-08-22 08:04:15 (GMT) |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2014-08-22 08:04:15 (GMT) |
commit | 80b304fd00e8b667775ff791121b61ecd7cd0c03 (patch) | |
tree | b4f2ec59fe062c43343ee4c2f10a6bcd0e4dcd1b /Documentation/networking/pktgen.txt | |
parent | fb21b84e7f809ef04b1e5aed5d463cf0d4866638 (diff) | |
parent | 6a7519e81321343165f89abb8b616df186d3e57a (diff) | |
download | linux-80b304fd00e8b667775ff791121b61ecd7cd0c03.tar.xz |
Merge tag 'efi-urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/mfleming/efi into x86/urgent
Pull EFI fixes from Matt Fleming:
* WARN_ON(!spin_is_locked()) always triggers on non-SMP machines.
Swap it for the more canonical lockdep_assert_held() which always
does the right thing - Guenter Roeck
* Assign the correct value to efi.runtime_version on arm64 so that all
the runtime services can be invoked - Semen Protsenko
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation/networking/pktgen.txt')
-rw-r--r-- | Documentation/networking/pktgen.txt | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/Documentation/networking/pktgen.txt b/Documentation/networking/pktgen.txt index 0e30c78..0dffc6e 100644 --- a/Documentation/networking/pktgen.txt +++ b/Documentation/networking/pktgen.txt @@ -24,6 +24,34 @@ For monitoring and control pktgen creates: /proc/net/pktgen/ethX +Tuning NIC for max performance +============================== + +The default NIC setting are (likely) not tuned for pktgen's artificial +overload type of benchmarking, as this could hurt the normal use-case. + +Specifically increasing the TX ring buffer in the NIC: + # ethtool -G ethX tx 1024 + +A larger TX ring can improve pktgen's performance, while it can hurt +in the general case, 1) because the TX ring buffer might get larger +than the CPUs L1/L2 cache, 2) because it allow more queueing in the +NIC HW layer (which is bad for bufferbloat). + +One should be careful to conclude, that packets/descriptors in the HW +TX ring cause delay. Drivers usually delay cleaning up the +ring-buffers (for various performance reasons), thus packets stalling +the TX ring, might just be waiting for cleanup. + +This cleanup issues is specifically the case, for the driver ixgbe +(Intel 82599 chip). This driver (ixgbe) combine TX+RX ring cleanups, +and the cleanup interval is affected by the ethtool --coalesce setting +of parameter "rx-usecs". + +For ixgbe use e.g "30" resulting in approx 33K interrupts/sec (1/30*10^6): + # ethtool -C ethX rx-usecs 30 + + Viewing threads =============== /proc/net/pktgen/kpktgend_0 |