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Helge Deller df95378d40 crypto: xor - fix template benchmarking 
[ Upstream commit ab9a244c39 ]

Commit c055e3eae0 ("crypto: xor - use ktime for template benchmarking")
switched from using jiffies to ktime-based performance benchmarking.

This works nicely on machines which have a fine-grained ktime()
clocksource as e.g. x86 machines with TSC.
But other machines, e.g. my 4-way HP PARISC server, don't have such
fine-grained clocksources, which is why it seems that 800 xor loops
take zero seconds, which then shows up in the logs as:

 xor: measuring software checksum speed
    8regs           : -1018167296 MB/sec
    8regs_prefetch  : -1018167296 MB/sec
    32regs          : -1018167296 MB/sec
    32regs_prefetch : -1018167296 MB/sec

Fix this with some small modifications to the existing code to improve
the algorithm to always produce correct results without introducing
major delays for architectures with a fine-grained ktime()
clocksource:
a) Delay start of the timing until ktime() just advanced. On machines
with a fast ktime() this should be just one additional ktime() call.
b) Count the number of loops. Run at minimum 800 loops and finish
earliest when the ktime() counter has progressed.

With that the throughput can now be calculated more accurately under all
conditions.

Fixes: c055e3eae0 ("crypto: xor - use ktime for template benchmarking")
Signed-off-by: Helge Deller <deller@gmx.de>
Tested-by: John David Anglin <dave.anglin@bell.net>

v2:
- clean up coding style (noticed & suggested by Herbert Xu)
- rephrased & fixed typo in commit message

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2024-10-17 15:20:36 +02:00
arch x86/mm: Switch to new Intel CPU model defines 2024-09-30 16:23:56 +02:00
block block: Fix where bio IO priority gets set 2024-09-30 16:23:50 +02:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: xor - fix template benchmarking 2024-10-17 15:20:36 +02:00
Documentation hwspinlock: Introduce hwspin_lock_bust() 2024-09-08 07:53:09 +02:00
drivers wifi: rtw88: always wait for both firmware loading attempts 2024-10-17 15:20:36 +02:00
fs btrfs: calculate the right space for delayed refs when updating global reserve 2024-09-30 16:23:55 +02:00
include netfilter: nft_set_pipapo: walk over current view on netlink dump 2024-09-30 16:23:54 +02:00
init rust: fix the default format for CONFIG_{RUSTC,BINDGEN}_VERSION_TEXT 2024-08-29 17:30:32 +02:00
io_uring io_uring/sqpoll: Do not set PF_NO_SETAFFINITY on sqpoll threads 2024-09-12 11:10:26 +02:00
ipc sysctl: treewide: drop unused argument ctl_table_root::set_ownership(table) 2024-08-11 12:35:51 +02:00
kernel bpf: Silence a warning in btf_type_id_size() 2024-09-12 11:10:29 +02:00
lib lib/generic-radix-tree.c: Fix rare race in __genradix_ptr_alloc() 2024-09-12 11:10:25 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: avoid leaving partial pfn mappings around in error case 2024-09-18 19:23:04 +02:00
net Revert "wifi: cfg80211: check wiphy mutex is held for wdev mutex" 2024-09-30 16:23:55 +02:00
rust rust: kbuild: fix export of bss symbols 2024-09-12 11:10:21 +02:00
samples bpf: Replace bpf_lpm_trie_key 0-length array with flexible array 2024-08-29 17:30:22 +02:00
scripts scripts: kconfig: merge_config: config files: add a trailing newline 2024-09-18 19:23:03 +02:00
security smack: unix sockets: fix accept()ed socket label 2024-09-12 11:10:19 +02:00
sound ASoC: tda7419: fix module autoloading 2024-09-30 16:23:49 +02:00
tools selftests: mptcp: join: restrict fullmesh endp on 1st sf 2024-09-30 16:23:55 +02:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-06-27 13:46:21 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add leah to 6.1 MAINTAINERS file 2024-05-17 11:56:16 +02:00
Makefile Linux 6.1.112 2024-09-30 16:23:56 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.