Gh0st
/
linux
mirror of https://github.com/torvalds/linux.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

percpu: Introduce percpu hot section 

Add a subsection to the percpu data for frequently accessed variables
that should remain cached on each processor.  These varables should not
be accessed from other processors to avoid cacheline bouncing.

This will replace the pcpu_hot struct on x86, and open up similar
functionality to other architectures and the kernel core.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250303165246.2175811-2-brgerst@gmail.com
This commit is contained in:
Brian Gerst 2025-03-03 11:52:36 -05:00 committed by Ingo Molnar
parent f3a3c29b8d
commit ab2bb9c084
2 changed files with 24 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
include/asm-generic/vmlinux.lds.h
View File

@ -385,6 +385,11 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG)
. = ALIGN(PAGE_SIZE); \
__nosave_end = .;
#define CACHE_HOT_DATA(align) \
. = ALIGN(align); \
*(SORT_BY_ALIGNMENT(.data..hot.*)) \
. = ALIGN(align);
#define PAGE_ALIGNED_DATA(page_align) \
. = ALIGN(page_align); \
*(.data..page_aligned) \
@ -1065,6 +1070,11 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG)
. = ALIGN(PAGE_SIZE); \
*(.data..percpu..page_aligned) \
. = ALIGN(cacheline); \
__per_cpu_hot_start = .; \
*(SORT_BY_ALIGNMENT(.data..percpu..hot.*)) \
__per_cpu_hot_pad = .; \
. = ALIGN(cacheline); \
__per_cpu_hot_end = .; \
*(.data..percpu..read_mostly) \
. = ALIGN(cacheline); \
*(.data..percpu) \
@ -1112,6 +1122,7 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG)
INIT_TASK_DATA(inittask) \
NOSAVE_DATA \
PAGE_ALIGNED_DATA(pagealigned) \
CACHE_HOT_DATA(cacheline) \
CACHELINE_ALIGNED_DATA(cacheline) \
READ_MOSTLY_DATA(cacheline) \
DATA_DATA \

13
include/linux/percpu-defs.h
View File

@ -112,6 +112,19 @@
#define DEFINE_PER_CPU(type, name) \
DEFINE_PER_CPU_SECTION(type, name, "")
/*
* Declaration/definition used for per-CPU variables that are frequently
* accessed and should be in a single cacheline.
*
* For use only by architecture and core code. Only use scalar or pointer
* types to maximize density.
*/
#define DECLARE_PER_CPU_CACHE_HOT(type, name) \
DECLARE_PER_CPU_SECTION(type, name, "..hot.." #name)
#define DEFINE_PER_CPU_CACHE_HOT(type, name) \
DEFINE_PER_CPU_SECTION(type, name, "..hot.." #name)
/*
* Declaration/definition used for per-CPU variables that must be cacheline
* aligned under SMP conditions so that, whilst a particular instance of the