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Helge Deller e55fcc821d crypto: xor - fix template benchmarking
[ Upstream commit ab9a244c396aae4aaa34b2399b82fc15ec2df8c1 ]

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>
2024-10-04 16:28:49 +02:00
Documentation hwspinlock: Introduce hwspin_lock_bust() 2024-09-08 07:54:43 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
arch x86/mm: Switch to new Intel CPU model defines 2024-09-30 16:25:14 +02:00
block block: Fix where bio IO priority gets set 2024-09-30 16:25:12 +02:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: xor - fix template benchmarking 2024-10-04 16:28:49 +02:00
drivers wifi: rtw88: always wait for both firmware loading attempts 2024-10-04 16:28:49 +02:00
fs ocfs2: strict bound check before memcmp in ocfs2_xattr_find_entry() 2024-09-30 16:25:12 +02:00
include netfilter: nft_set_pipapo: walk over current view on netlink dump 2024-09-30 16:25:13 +02:00
init rust: fix the default format for CONFIG_{RUSTC,BINDGEN}_VERSION_TEXT 2024-08-29 17:33:29 +02:00
io_uring io_uring: fix io_match_task must_hold 2024-08-03 08:54:41 +02:00
ipc sysctl: treewide: drop unused argument ctl_table_root::set_ownership(table) 2024-08-11 12:47:13 +02:00
kernel tracing/osnoise: Fix build when timerlat is not enabled 2024-09-18 19:24:09 +02:00
lib lib/generic-radix-tree.c: Fix rare race in __genradix_ptr_alloc() 2024-09-12 11:11:39 +02:00
mm mm: avoid leaving partial pfn mappings around in error case 2024-09-18 19:24:07 +02:00
net Revert "wifi: cfg80211: check wiphy mutex is held for wdev mutex" 2024-09-30 16:25:14 +02:00
rust rust: kbuild: fix export of bss symbols 2024-09-12 11:11:32 +02:00
samples bpf: Replace bpf_lpm_trie_key 0-length array with flexible array 2024-08-19 06:04:27 +02:00
scripts scripts: kconfig: merge_config: config files: add a trailing newline 2024-09-18 19:24:05 +02:00
security smack: unix sockets: fix accept()ed socket label 2024-09-12 11:11:29 +02:00
sound ALSA: hda: add HDMI codec ID for Intel PTL 2024-09-30 16:25:11 +02:00
tools tools: hv: rm .*.cmd when make clean 2024-09-30 16:25:12 +02:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-06-27 13:49:11 +02:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
.mailmap 20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues 2023-10-24 09:52:16 -10:00
.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 USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
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 membarrier: riscv: Add full memory barrier in switch_mm() 2024-09-12 11:11:45 +02:00
Makefile Linux 6.6.53 2024-09-30 16:25:15 +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.