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Nayna Jain a233a0289c tpm: msleep() delays - replace with usleep_range() in i2c nuvoton driver 
Commit 500462a9de "timers: Switch to a non-cascading wheel" replaced
the 'classic' timer wheel, which aimed for near 'exact' expiry of the
timers.  Their analysis was that the vast majority of timeout timers
are used as safeguards, not as real timers, and are cancelled or
rearmed before expiration.  The only exception noted to this were
networking timers with a small expiry time.

Not included in the analysis was the TPM polling timer, which resulted
in a longer normal delay and, every so often, a very long delay.  The
non-cascading wheel delay is based on CONFIG_HZ.  For a description of
the different rings and their delays, refer to the comments in
kernel/time/timer.c.

Below are the delays given for rings 0 - 2, which explains the longer
"normal" delays and the very, long delays as seen on systems with
CONFIG_HZ 250.

* HZ 1000 steps
 * Level Offset  Granularity            Range
 *  0      0         1 ms                0 ms - 63 ms
 *  1     64         8 ms               64 ms - 511 ms
 *  2    128        64 ms              512 ms - 4095 ms (512ms - ~4s)

* HZ  250
 * Level Offset  Granularity            Range
 *  0      0         4 ms                0 ms - 255 ms
 *  1     64        32 ms              256 ms - 2047 ms (256ms - ~2s)
 *  2    128       256 ms             2048 ms - 16383 ms (~2s - ~16s)

Below is a comparison of extending the TPM with 1000 measurements,
using msleep() vs. usleep_delay() when configured for 1000 hz vs. 250
hz, before and after commit 500462a9de.

linux-4.7 | msleep() usleep_range()
1000 hz: 0m44.628s | 1m34.497s 29.243s
250 hz: 1m28.510s | 4m49.269s 32.386s

linux-4.7  | min-max (msleep)  min-max (usleep_range)
1000 hz: 0:017 - 2:760s | 0:015 - 3:967s    0:014 - 0:418s
250 hz: 0:028 - 1:954s | 0:040 - 4:096s    0:016 - 0:816s

This patch replaces the msleep() with usleep_range() calls in the
i2c nuvoton driver with a consistent max range value.

Signed-of-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org (linux-4.8)
Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
 		2017-04-03 22:46:00 +03:00
Documentation Char/Misc driver fixes for 4.11-rc4 2017-03-26 11:15:54 -07:00
arch powerpc fixes for 4.11 #6 2017-03-26 10:34:10 -07:00
block blk-mq: don't complete un-started request in timeout handler 2017-03-22 08:03:35 -06:00
certs certs: Add a secondary system keyring that can be added to dynamically 2016-04-11 22:48:09 +01:00
crypto net: Work around lockdep limitation in sockets that use sockets 2017-03-09 18:23:27 -08:00
drivers tpm: msleep() delays - replace with usleep_range() in i2c nuvoton driver 2017-04-03 22:46:00 +03:00
firmware WHENCE: use https://linuxtv.org for LinuxTV URLs 2015-12-04 10:35:11 -02:00
fs driver core fix for 4.11-rc4 2017-03-26 11:05:42 -07:00
include security, keys: convert key.usage from atomic_t to refcount_t 2017-04-03 10:49:05 +10:00
init Change get_random_{int,log} to use the CRNG used by /dev/urandom and 2017-03-11 09:08:47 -08:00
ipc Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-03-03 10:16:38 -08:00
kernel LSM: Revive security_task_alloc() hook and per "struct task_struct" security blob. 2017-03-28 11:05:14 +11:00
lib mm: convert generic code to 5-level paging 2017-03-09 11:48:47 -08:00
mm mm, swap: Remove WARN_ON_ONCE() in free_swap_slot() 2017-03-21 14:13:19 -07:00
net A fix for a writeback deadlock caused by a GFP_KERNEL allocation on the 2017-03-24 14:35:39 -07:00
samples Merge branch 'rebased-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-03-03 11:38:56 -08:00
scripts Merge branch 'akpm' (patches from Andrew) 2017-03-10 08:34:42 -08:00
security security, keys: convert key_user.usage from atomic_t to refcount_t 2017-04-03 10:49:06 +10:00
sound ALSA: hda - Adding a group of pin definition to fix headset problem 2017-03-23 09:39:55 +01:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-03-23 11:29:49 -07:00
usr kbuild: initramfs cleanup, set target from Kconfig 2017-01-05 09:40:16 -08:00
virt KVM: arm/arm64: VGIC: Fix command handling while ITS being disabled 2017-03-07 15:44:08 +00:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Merge branch 'misc' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2016-08-02 16:48:52 -04:00
.mailmap mailmap: add codeaurora.org names for nameless email commits 2017-01-10 18:31:55 -08:00
COPYING
…
CREDITS MAINTAINERS: Remove old e-mail address 2017-02-13 12:24:56 -05:00
Kbuild scripts/gdb: provide linux constants 2016-05-23 17:04:14 -07:00
Kconfig
…
MAINTAINERS enic: update enic maintainers 2017-03-22 12:48:55 -07:00
Makefile Linux 4.11-rc4 2017-03-26 14:15:16 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

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.