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Tal Gilboa 53acd76ce5 net/mlx5e: Fix wrong indications in DIM due to counter wraparound
DIM (Dynamically-tuned Interrupt Moderation) is a mechanism designed for
changing the channel interrupt moderation values in order to reduce CPU
overhead for all traffic types.
Each iteration of the algorithm, DIM calculates the difference in
throughput, packet rate and interrupt rate from last iteration in order
to make a decision. DIM relies on counters for each metric. When these
counters get to their type's max value they wraparound. In this case
the delta between 'end' and 'start' samples is negative and when
translated to unsigned integers - very high. This results in a false
indication to the algorithm and might result in a wrong decision.

The fix calculates the 'distance' between 'end' and 'start' samples in a
cyclic way around the relevant type's max value. It can also be viewed as
an absolute value around the type's max value instead of around 0.

Testing show higher stability in DIM profile selection and no wraparound
issues.

Fixes: cb3c7fd4f8 ("net/mlx5e: Support adaptive RX coalescing")
Signed-off-by: Tal Gilboa <talgi@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
2017-06-11 13:10:36 +03:00
arch bpf, arm64: use separate register for state in stxr 2017-06-07 15:27:20 -04:00
block
certs
crypto
Documentation net: fix up hash documentation 2017-06-07 13:00:41 -04:00
drivers net/mlx5e: Fix wrong indications in DIM due to counter wraparound 2017-06-11 13:10:36 +03:00
firmware
fs fs/ufs: Set UFS default maximum bytes per file 2017-06-04 16:33:54 -07:00
include ethtool.h: remind to update 802.3ad when adding new speeds 2017-06-08 16:05:41 -04:00
init Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-10 10:30:46 -07:00
ipc
kernel Merge branch 'for-4.12-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2017-06-05 15:37:03 -07:00
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net net: tipc: Fix a sleep-in-atomic bug in tipc_msg_reverse 2017-06-10 18:20:38 -04:00
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tools bpf, tests: fix endianness selection 2017-06-08 16:17:29 -04:00
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MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-06-06 14:30:17 -07:00
Makefile Linux 4.12-rc4 2017-06-04 16:47:43 -07:00
README

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.