From 0db324e2e5d9d3347ea0e93138372fb65aac09e6 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Mon, 15 Apr 2024 21:41:09 +0200
Subject: Merging upstream version 6.7.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 man2/membarrier.2 | 46 +++++++++++++++++++++++-----------------------
 1 file changed, 23 insertions(+), 23 deletions(-)

(limited to 'man2/membarrier.2')

diff --git a/man2/membarrier.2 b/man2/membarrier.2
index f118fd0..ce5a9de 100644
--- a/man2/membarrier.2
+++ b/man2/membarrier.2
@@ -3,7 +3,7 @@
 .\"
 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
 .\"
-.TH membarrier 2 2023-05-03 "Linux man-pages 6.05.01"
+.TH membarrier 2 2023-10-31 "Linux man-pages 6.7"
 .SH NAME
 membarrier \- issue memory barriers on a set of threads
 .SH LIBRARY
@@ -11,16 +11,16 @@ Standard C library
 .RI ( libc ", " \-lc )
 .SH SYNOPSIS
 .nf
-.PP
+.P
 .BR "#include <linux/membarrier.h>" \
 " /* Definition of " MEMBARRIER_* " constants */"
 .BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
 .B #include <unistd.h>
-.PP
+.P
 .BI "int syscall(SYS_membarrier, int " cmd ", unsigned int " flags \
 ", int " cpu_id );
 .fi
-.PP
+.P
 .IR Note :
 glibc provides no wrapper for
 .BR membarrier (),
@@ -36,12 +36,12 @@ effectively is
 .I not
 as simple as replacing memory barriers with this
 system call, but requires understanding of the details below.
-.PP
+.P
 Use of memory barriers needs to be done taking into account that a
 memory barrier always needs to be either matched with its memory barrier
 counterparts, or that the architecture's memory model doesn't require the
 matching barriers.
-.PP
+.P
 There are cases where one side of the matching barriers (which we will
 refer to as "fast side") is executed much more often than the other
 (which we will refer to as "slow side").
@@ -50,22 +50,22 @@ This is a prime target for the use of
 The key idea is to replace, for these matching
 barriers, the fast-side memory barriers by simple compiler barriers,
 for example:
-.PP
+.P
 .in +4n
 .EX
 asm volatile ("" : : : "memory")
 .EE
 .in
-.PP
+.P
 and replace the slow-side memory barriers by calls to
 .BR membarrier ().
-.PP
+.P
 This will add overhead to the slow side, and remove overhead from the
 fast side, thus resulting in an overall performance increase as long as
 the slow side is infrequent enough that the overhead of the
 .BR membarrier ()
 calls does not outweigh the performance gain on the fast side.
-.PP
+.P
 The
 .I cmd
 argument is one of the following:
@@ -183,7 +183,7 @@ Register the process's intent to use
 This is an alias for
 .B MEMBARRIER_CMD_GLOBAL
 that exists for header backward compatibility.
-.PP
+.P
 The
 .I flags
 argument must be specified as 0 unless the command is
@@ -192,7 +192,7 @@ in which case
 .I flags
 can be either 0 or
 .BR MEMBARRIER_CMD_FLAG_CPU .
-.PP
+.P
 The
 .I cpu_id
 argument is ignored unless
@@ -201,11 +201,11 @@ is
 .BR MEMBARRIER_CMD_FLAG_CPU ,
 in which case it must specify the CPU targeted by this membarrier
 command.
-.PP
+.P
 All memory accesses performed in program order from each targeted thread
 are guaranteed to be ordered with respect to
 .BR membarrier ().
-.PP
+.P
 If we use the semantic
 .I barrier()
 to represent a compiler barrier forcing memory
@@ -219,7 +219,7 @@ each pairing of
 and
 .IR smp_mb() .
 The pair ordering is detailed as (O: ordered, X: not ordered):
-.PP
+.P
 .RS
 .TS
 l c c c.
@@ -246,7 +246,7 @@ On error, \-1 is returned,
 and
 .I errno
 is set to indicate the error.
-.PP
+.P
 For a given command, with
 .I flags
 set to 0, this system call is
@@ -284,9 +284,9 @@ commands.
 Linux.
 .SH HISTORY
 Linux 4.3.
-.PP
+.P
 Before Linux 5.10, the prototype was:
-.PP
+.P
 .in +4n
 .EX
 .BI "int membarrier(int " cmd ", int " flags );
@@ -301,10 +301,10 @@ matching barriers on other cores.
 For instance, a load fence can order
 loads prior to and following that fence with respect to stores ordered
 by store fences.
-.PP
+.P
 Program order is the order in which instructions are ordered in the
 program assembly code.
-.PP
+.P
 Examples where
 .BR membarrier ()
 can be useful include implementations
@@ -314,7 +314,7 @@ Assuming a multithreaded application where "fast_path()" is executed
 very frequently, and where "slow_path()" is executed infrequently, the
 following code (x86) can be transformed using
 .BR membarrier ():
-.PP
+.P
 .in +4n
 .\" SRC BEGIN (membarrier.c)
 .EX
@@ -365,11 +365,11 @@ main(void)
 .EE
 .\" SRC END
 .in
-.PP
+.P
 The code above transformed to use
 .BR membarrier ()
 becomes:
-.PP
+.P
 .in +4n
 .EX
 #define _GNU_SOURCE
-- 
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