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Vincent Whitchurch bea022cf22 perf bench mem: Always memset source before memcpy 
[ Upstream commit 1beaef29c34154ccdcb3f1ae557f6883eda18840 ]

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: 47b5757bac03c338 ("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>
 		2021-03-16 16:34:22 +08:00
Documentation dt-bindings: iio: io-channel-mux: Fix compatible string in example code 2021-03-16 16:34:03 +08:00
LICENSES Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
arch x86/tsr: Fix tsc frequency enumeration bug on Lightning Mountain SoC 2021-03-16 16:34:19 +08:00
block iocost: Fix check condition of iocg abs_vdebt 2021-03-16 16:33:18 +08:00
certs Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
crypto crypto: algif_aead - fix uninitialized ctx->init 2021-03-16 16:34:22 +08:00
drivers mfd: dln2: Run event handler loop under spinlock 2021-03-16 16:34:21 +08:00
fs fs/ufs: avoid potential u32 multiplication overflow 2021-03-16 16:34:21 +08:00
include iommu/vt-d: Enforce PASID devTLB field mask 2021-03-16 16:34:16 +08:00
init x86: Fix early boot crash on gcc-10, third try 2021-03-16 16:28:02 +08:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2021-03-16 16:27:51 +08:00
kernel module: Correctly truncate sysfs sections output 2021-03-16 16:34:09 +08:00
lib test_kmod: avoid potential double free in trigger_config_run_type() 2021-03-16 16:34:21 +08:00
mm mm/memory_hotplug: fix unpaired mem_hotplug_begin/done 2021-03-16 16:34:07 +08:00
net mac80211: fix misplaced while instead of if 2021-03-16 16:34:06 +08:00
package config/arm64: OPEN CONFIG_PSI and phytium configs 2021-03-16 11:02:59 +08:00
samples bpf: Fix fds_example SIGSEGV error 2021-03-16 16:33:24 +08:00
scripts recordmcount: Fix build failure on non arm64 2021-03-16 16:34:19 +08:00
security Smack: prevent underflow in smk_set_cipso() 2021-03-16 16:33:40 +08:00
sound ALSA: echoaudio: Fix potential Oops in snd_echo_resume() 2021-03-16 16:34:22 +08:00
tools perf bench mem: Always memset source before memcpy 2021-03-16 16:34:22 +08:00
usr Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
virt KVM: arm64: Don't inherit exec permission across page-table levels 2021-03-16 16:32:57 +08:00
.clang-format Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
.cocciconfig Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
.get_maintainer.ignore Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
.gitattributes Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
.gitignore Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
COPYING Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
CREDITS Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
Kbuild Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
Kconfig Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
MAINTAINERS Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
Makefile Makefile: Fix GCC_TOOLCHAIN_DIR prefix for Clang cross compilation 2021-03-16 16:32:37 +08:00
README Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
README.md Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
backport_remove_lists.txt Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
tools_key.pub Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00

README.md

Tencent Linux Kernel 4.0