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Neal Cardwell 3aff3b4b98 tcp_bbr: fix pacing_gain to always be unity when using lt_bw
This commit fixes the pacing_gain to remain at BBR_UNIT (1.0) when
using lt_bw and returning from the PROBE_RTT state to PROBE_BW.

Previously, when using lt_bw, upon exiting PROBE_RTT and entering
PROBE_BW the bbr_reset_probe_bw_mode() code could sometimes randomly
end up with a cycle_idx of 0 and hence have bbr_advance_cycle_phase()
set a pacing gain above 1.0. In such cases this would result in a
pacing rate that is 1.25x higher than intended, potentially resulting
in a high loss rate for a little while until we stop using the lt_bw a
bit later.

This commit is a stable candidate for kernels back as far as 4.9.

Fixes: 0f8782ea14 ("tcp_bbr: add BBR congestion control")
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Reported-by: Beyers Cronje <bcronje@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-02-01 09:43:38 -05:00
arch Merge branch 'work.whack-a-mole' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-31 19:18:12 -08:00
block Merge branch 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-30 17:58:07 -08:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-01-31 14:22:45 -08:00
Documentation Documentation updates for 4.16. New stuff includes refcount_t 2018-01-31 19:25:25 -08:00
drivers be2net: remove redundant initialization of 'head' and pointer txq 2018-02-01 09:43:00 -05:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs Documentation updates for 4.16. New stuff includes refcount_t 2018-01-31 19:25:25 -08:00
include net: create skb_gso_validate_mac_len() 2018-02-01 09:36:03 -05:00
init init_task out-of-lining 2018-01-29 09:08:34 -08:00
ipc Merge branch 'work.mqueue' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-30 18:32:21 -08:00
kernel Merge branch 'akpm' (patches from Andrew) 2018-01-31 18:46:22 -08:00
lib Documentation updates for 4.16. New stuff includes refcount_t 2018-01-31 19:25:25 -08:00
LICENSES LICENSES: Add MPL-1.1 license 2018-01-06 10:59:44 -07:00
mm mm/swap.c: make functions and their kernel-doc agree 2018-01-31 17:18:40 -08:00
net tcp_bbr: fix pacing_gain to always be unity when using lt_bw 2018-02-01 09:43:38 -05:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-01-31 14:31:10 -08:00
scripts Documentation updates for 4.16. New stuff includes refcount_t 2018-01-31 19:25:25 -08:00
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-01-31 14:31:10 -08:00
sound Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-31 09:25:20 -08:00
tools Merge branch 'akpm' (patches from Andrew) 2018-01-31 18:46:22 -08:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt mm, mmu_notifier: annotate mmu notifiers with blockable invalidate callbacks 2018-01-31 17:18:38 -08:00
.cocciconfig
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.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild misc updates for v4.15 2017-11-17 17:51:33 -08:00
.mailmap mailmap: update Mark Yao's email address 2018-01-04 16:45:09 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-01-31 14:31:10 -08:00
Makefile Linux 4.15 2018-01-28 13:20:33 -08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

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.