482c613e4f
[ Upstream commit 2a6e5fa2f4c25b66c763428a3e65363214946931 ]
>From the documentation of round_jiffies():
"Rounds a time delta in the future (in jiffies) up or down to
(approximately) full seconds. This is useful for timers for which
the exact time they fire does not matter too much, as long as
they fire approximately every X seconds.
By rounding these timers to whole seconds, all such timers will fire
at the same time, rather than at various times spread out. The goal
of this is to have the CPU wake up less, which saves power."
There are 2 parts to this patch:
================================
Part 1:
-------
In our case we need timer_service to be called approximately every
X=1 seconds, and the exact time does not matter, so using round_jiffies()
is the right way to go.
Therefore we add round_jiffies() to the mod_timer() in ena_timer_service().
Part 2:
-------
round_jiffies() is used in check_for_missing_keep_alive() when
getting the jiffies of the expiration of the keep_alive timeout. Here it
is actually a mistake to use round_jiffies() because we want the exact
time when keep_alive should expire and not an approximate rounded time,
which can cause early, false positive, timeouts.
Therefore we remove round_jiffies() in the calculation of
keep_alive_expired() in check_for_missing_keep_alive().
Fixes: 82ef30f13be0 ("net: ena: add hardware hints capability to the driver")
Fixes: 1738cd3ed342 ("net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)")
Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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.