No description
Find a file
Vincent Whitchurch 23e444f934 perf bench mem: Always memset source before memcpy
[ Upstream commit 1beaef29c3 ]

For memcpy, the source pages are memset to zero only when --cycles is
used.  This leads to wildly different results with or without --cycles,
since all sources pages are likely to be mapped to the same zero page
without explicit writes.

Before this fix:

$ export cmd="./perf stat -e LLC-loads -- ./perf bench \
  mem memcpy -s 1024MB -l 100 -f default"
$ $cmd

         2,935,826      LLC-loads
       3.821677452 seconds time elapsed

$ $cmd --cycles

       217,533,436      LLC-loads
       8.616725985 seconds time elapsed

After this fix:

$ $cmd

       214,459,686      LLC-loads
       8.674301124 seconds time elapsed

$ $cmd --cycles

       214,758,651      LLC-loads
       8.644480006 seconds time elapsed

Fixes: 47b5757bac ("perf bench mem: Move boilerplate memory allocation to the infrastructure")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kernel@axis.com
Link: http://lore.kernel.org/lkml/20200810133404.30829-1-vincent.whitchurch@axis.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-08-21 09:48:23 +02:00
arch pseries: Fix 64 bit logical memory block panic 2020-08-21 09:48:20 +02:00
block block/bio-integrity: don't free 'buf' if bio_integrity_add_page() failed 2020-06-30 15:37:57 -04:00
certs Replace magic for trusting the secondary keyring with #define 2018-09-09 19:55:54 +02:00
crypto crypto: af_alg - fix use-after-free in af_alg_accept() due to bh_lock_sock() 2020-07-09 09:36:30 +02:00
Documentation dt-bindings: iio: io-channel-mux: Fix compatible string in example code 2020-08-21 09:48:17 +02:00
drivers mfd: dln2: Run event handler loop under spinlock 2020-08-21 09:48:22 +02:00
firmware Fix built-in early-load Intel microcode alignment 2020-01-23 08:20:30 +01:00
fs fs/ufs: avoid potential u32 multiplication overflow 2020-08-21 09:48:22 +02:00
include iommu/vt-d: Enforce PASID devTLB field mask 2020-08-21 09:48:21 +02:00
init x86: Fix early boot crash on gcc-10, third try 2020-05-20 08:17:15 +02:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:17:07 +02:00
kernel tracing: Use trace_sched_process_free() instead of exit() for pid tracing 2020-08-21 09:48:19 +02:00
lib test_kmod: avoid potential double free in trigger_config_run_type() 2020-08-21 09:48:22 +02:00
mm mm/mmap.c: Add cond_resched() for exit_mmap() CPU stalls 2020-08-21 09:48:05 +02:00
net mac80211: fix misplaced while instead of if 2020-08-21 09:48:18 +02:00
samples samples: bpf: Fix build error 2020-06-03 08:17:55 +02:00
scripts scripts/decode_stacktrace: strip basepath from all paths 2020-07-29 07:42:54 +02:00
security Smack: prevent underflow in smk_set_cipso() 2020-08-21 09:48:11 +02:00
sound ALSA: echoaudio: Fix potential Oops in snd_echo_resume() 2020-08-21 09:48:23 +02:00
tools perf bench mem: Always memset source before memcpy 2020-08-21 09:48:23 +02:00
usr initramfs: restore default compression behavior 2020-04-13 10:34:19 +02:00
virt KVM: arm: vgic: Fix limit condition when writing to GICD_I[CS]ACTIVER 2020-05-20 08:16:58 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore kbuild: rpm-pkg: keep spec file until make mrproper 2018-02-13 10:19:46 +01:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS MAINTAINERS: Update drm/i915 bug filing URL 2020-02-28 16:36:12 +01:00
Makefile Linux 4.14.193 2020-08-07 09:38:42 +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.